Protocol Independent Multicast (PIM) provides IP multicast forwarding by leveraging unicast static routes or unicast routing tables generated by any unicast routing protocol, such as RIP, OSPF, IS-IS, or BGP. PIM is not dependent on any particular unicast routing protocol, and it uses the underlying unicast routing to generate a routing table with routes.

PIM uses the RPF mechanism to implement multicast forwarding. When a multicast packet arrives on an interface of the device, it undergoes an RPF check. If the RPF check succeeds, the device creates a multicast routing entry and forwards the packet. If the RPF check fails, the device discards the packet. For more information about RPF, see "Configuring multicast routing and forwarding."

Based on the implementation mechanism, PIM includes the following categories:

· Protocol Independent Multicast–Dense Mode (PIM-DM)

· Protocol Independent Multicast–Sparse Mode (PIM-SM)

· Protocol Independent Multicast Source-Specific Multicast (PIM-SSM)

The term "PIM domain" in this chapter refers to a network composed of PIM routers.

The term "interface" in this chapter collectively refers to VLAN interfaces and Layer 3 Ethernet interfaces. You can set an Ethernet port as a Layer 3 interface by using the port link-mode route command (see Layer 2—LAN Switching Configuration Guide).

PIM-DM overview

PIM-DM uses the push mode for multicast forwarding, and is suitable for small-sized networks with densely distributed multicast members.

The following describes the basic implementation of PIM-DM:

· PIM-DM assumes that all downstream nodes want to receive multicast data from a source, so multicast data is flooded to all downstream nodes on the network.

· Branches without downstream receivers are pruned from the forwarding trees, leaving only those branches that contain receivers.

· The pruned state of a branch has a finite holdtime timer. When the timer expires, multicast data is again forwarded to the pruned branch. This flood-and-prune cycle takes place periodically to maintain the forwarding branches.

· The graft mechanism is used to reduce the latency for resuming the forwarding capability of a previously pruned branch.

In PIM-DM, the multicast forwarding paths for a multicast group constitutes a source tree, which is rooted at the multicast source and has multicast group members as its "leaves." Because the source tree consists of the shortest paths from the multicast source to the receivers, it is also called a "shortest path tree (SPT)."

Neighbor discovery

In a PIM domain, each interface that runs PIM on a router periodically multicasts PIM hello messages to all other PIM routers (identified by the address 224.0.0.13) on the local subnet. Through the exchanging of hello messages, all PIM routers on the subnet determine their PIM neighbors, maintain PIM neighboring relationship with other routers, and build and maintain SPTs.

SPT building

The process of building an SPT is the flood-and-prune process:

1. In a PIM-DM domain, when the multicast source S sends multicast data to the multicast group G, the multicast data is flooded throughout the domain. A router performs an RPF check for the multicast data. If the RPF check succeeds, the router creates an (S, G) entry and forwards the data to all downstream nodes in the network. In the flooding process, all the routers in the PIM-DM domain create the (S, G) entry.

2. The nodes without downstream receivers are pruned. A router that has no downstream receivers sends a prune message to the upstream node to remove the interface that receives the prune message from the (S, G) entry. In this way, the upstream stream node stops forwarding subsequent packets addressed to that multicast group down to this node.

NOTE:

An (S, G) entry contains a multicast source address S, a multicast group address G, an outgoing interface list, and an incoming interface.

A prune process is initiated by a leaf router. As shown in Figure 1, the router interface that does not have any downstream receivers initiates a prune process by sending a prune message toward the multicast source. This prune process goes on until only necessary branches are left in the PIM-DM domain, and these necessary branches constitute an SPT.

Figure 1 SPT building

The pruned state of a branch has a finite holdtime timer. When the timer expires, multicast data is again forwarded to the pruned branch. The flood-and-prune cycle takes place periodically to maintain the forwarding branches.

Graft

A previously pruned branch might have new downstream receivers. To reduce the latency for resuming the forwarding capability of this branch, a graft mechanism is used as follows:

1. The node that needs to receive the multicast data sends a graft message to its upstream node, telling it to rejoin the SPT.

2. After receiving this graft message on an interface, the upstream node adds the receiving interface into the outgoing interface list of the (S, G) entry. It also sends a graft-ack message to the graft sender.

3. If the graft sender receives a graft-ack message, the graft process finishes. Otherwise, the graft sender continues to send graft messages at a graft retry interval until it receives an acknowledgment from its upstream node.

Assert

On a subnet with more than one multicast router, the assert mechanism shuts off duplicate multicast flows to the network. It does this by electing a unique multicast forwarder for the subnet.

Figure 2 Assert mechanism

As shown in Figure 2, after Router A and Router B receive an (S, G) packet from the upstream node, they both forward the packet to the local subnet. As a result, the downstream node Router C receives two identical multicast packets. Both Router A and Router B, on their own downstream interfaces, receive a duplicate packet forwarded by the other. After detecting this condition, both routers send an assert message to all PIM routers (224.0.0.13) on the local subnet through the interface that received the packet. The assert message contains the multicast source address (S), the multicast group address (G), and the metric preference and metric of the unicast route/static multicast route to the multicast source. By comparing these parameters, either Router A or Router B becomes the unique forwarder of the subsequent (S, G) packets on the shared-media LAN. The comparison process is as follows:

1. The router with a higher preference to the multicast source wins.

2. If both routers have the same metric preference to the source, the router with a smaller metric wins.

3. If both routers have the same metric, the router with a higher IP address on the downstream interface wins.

PIM-SM overview

PIM-DM uses the flood-and-prune cycles to build SPTs for multicast data forwarding. Although an SPT has the shortest paths from the multicast source to the receivers, it is built with a low efficiency and is not suitable for large- and medium-sized networks.

PIM-SM uses the pull mode for multicast forwarding, and it is suitable for large- and medium-sized networks with sparsely and widely distributed multicast group members.

The basic implementation of PIM-SM is as follows:

· PIM-SM assumes that no hosts need multicast data. In the PIM-SM mode, a host must express its interest in the multicast data for a multicast group before the data is forwarded to it. PIM-SM implements multicast forwarding by building and maintaining rendezvous point trees (RPTs). An RPT is rooted at a router that has been configured as the rendezvous point (RP) for a multicast group. The multicast data to the group is forwarded by the RP to the receivers along the RPT.

· When a receiver host joins a multicast group, the receiver-side designated router (DR) sends a join message to the RP for the multicast group. The path along which the message goes hop by hop to the RP forms a branch of the RPT.

· When a multicast source sends multicast data to a multicast group, the source-side DR must register the multicast source with the RP by unicasting register messages to the RP. The multicast source stops sending until it receives a register-stop message from the RP. When the RP receives the register message, it triggers the establishment of an SPT. Then, the multicast source sends subsequent multicast packets along the SPT to the RP. After reaching the RP, the multicast packet is duplicated and delivered to the receivers along the RPT.

Multicast data is replicated wherever the RPT branches, and this process automatically repeats until the multicast data reaches the receivers.

Neighbor discovery

PIM-SM uses the same neighbor discovery mechanism as PIM-DM does. For more information, see "Neighbor discovery."

DR election

On a shared-media LAN like Ethernet, only a DR forwards the multicast data. A DR is required in both the source-side network and receiver-side network. A source-side DR acts on behalf of the multicast source to send register messages to the RP. The receiver-side DR acts on behalf of the receiver hosts to send join messages to the RP.

PIM-DM does not require a DR. However, if IGMPv1 runs on any shared-media LAN in a PIM-DM domain, a DR must be elected to act as the IGMPv1 querier for the LAN. For more information about IGMP, see "Configuring IGMP."

IMPORTANT:

IGMP must be enabled on the device that acts as the receiver-side DR. Otherwise, the receiver hosts attached to the DR cannot join any multicast groups.

Figure 3 DR election

As shown in Figure 3, the DR election process is as follows:

1. The routers on the shared-media LAN send hello messages to one another. The hello messages contain the priority for DR election. The router with the highest DR priority is elected as the DR.

2. The router with the highest IP address wins the DR election under one of following conditions:

¡ All the routers have the same DR election priority.

¡ A router does not support carrying the DR-election priority in hello messages.

If the DR fails, its PIM neighbor lifetime expires and the other routers will initiate to elect a new DR.

RP discovery

An RP is the core of a PIM-SM domain. For a small-sized, simple network, one RP is enough for multicast forwarding throughout the network. In this case, you can specify a static RP on each router in the PIM-SM domain. However, in a PIM-SM network that covers a wide area, a huge amount of multicast data is forwarded by the RP. To lessen the RP burden and optimize the topological structure of the RPT, you can configure multiple candidate-RPs (C-RPs) in a PIM-SM domain. The bootstrap mechanism is used to dynamically elect RPs from multiple C-RPs. An elected RP provides services for a different multicast group. For this purpose, you must configure a bootstrap router (BSR). A BSR serves as the administrative core of a PIM-SM domain. A PIM-SM domain has only one BSR, but can have multiple candidate-BSRs (C-BSRs) so that, if the BSR fails, a new BSR can be automatically elected from the C-BSRs and avoid service interruption.

NOTE:

· An RP can provide services for multiple multicast groups, but a multicast group only uses one RP.

· A device can act as a C-RP and a C-BSR at the same time.

As shown in Figure 4, each C-RP periodically unicasts its advertisement messages (C-RP-Adv messages) to the BSR. An advertisement message contains the address of the advertising C-RP and the multicast group range to which it is designated. The BSR collects these advertisement messages and organizes the C-RP information into an RP-set, which is a database of mappings between multicast groups and RPs. The BSR encapsulates the RP-set information in the bootstrap messages (BSMs) and floods the BSMs to the entire PIM-SM domain.

Figure 4 Information exchange between C-RPs and BSR

Based on the information in the RP-set, all routers in the network can select an RP for a specific multicast group based on the following rules:

1. The C-RP that is designated to a smallest group range wins.

2. If the C-RPs are designated to the same group range, the C-RP with the highest priority wins.

3. If the C-RPs have the same priority, the C-RP with the largest hash value wins. The hash value is calculated through the hash algorithm.

4. If the C-RPs have the same hash value, the C-RP with the highest IP address wins.

RPT building

Figure 5 RPT building in a PIM-SM domain

As shown in Figure 5, the process of building an RPT is as follows:

1. When a receiver wants to join the multicast group G, it uses an IGMP message to inform the receiver-side DR.

2. After getting the receiver information, the DR sends a join message, which is forwarded hop by hop to the RP for the multicast group.

3. The routers along the path from the DR to the RP form an RPT branch. Each router on this branch adds to its forwarding table a (*, G) entry, where the asterisk (*) represents any multicast source. The RP is the root of the RPT, and the DR is a leaf of the RPT.

When the multicast data addressed to the multicast group G reaches the RP, the RP forwards the data to the DR along the established RPT, and finally to the receiver.

When a receiver is no longer interested in the multicast data addressed to the multicast group G, the receiver-side DR sends a prune message. The prune message goes hop by hop along the RPT to the RP. After receiving the prune message, the upstream node deletes the interface that connects to this downstream node from the outgoing interface list. It also determines whether it has receivers for that multicast group. If not, the router continues to forward the prune message to its upstream router.

Multicast source registration

The multicast source uses the registration process to inform an RP of its presence.

Figure 6 Multicast source registration

As shown in Figure 6, the multicast source registers with the RP as follows:

1. The multicast source S sends the first multicast packet to the multicast group G. When receiving the multicast packet, the source-side DR encapsulates the packet in a PIM register message and unicasts the message to the RP.

2. After the RP receives the register message, it decapsulates the register message and forwards the register message down to the RPT. Meanwhile, it sends an (S, G) source-specific join message toward the multicast source. The routers along the path from the RP to the multicast source constitute an SPT branch. Each router on this branch creates an (S, G) entry in its forwarding table.

3. The subsequent multicast data from the multicast source are forwarded to the RP along the established SPT. When the multicast data reaches the RP along the SPT, the RP forwards the data to the receivers along the RPT. Meanwhile, it unicasts a register-stop message to the source-side DR to prevent the DR from unnecessarily encapsulating the data.

Switchover to SPT

In a PIM-SM domain, only one RP and one RPT provide services for a specific multicast group. Before the switchover to SPT occurs, the source-side DR encapsulates all multicast data addressed to the multicast group in register messages and sends them to the RP. After receiving these register messages, the RP decapsulates them and forwards them to the receivers-side DR along the RPT.

Switchover to SPT has the following weaknesses:

· Encapsulation and decapsulation are complex on the source-side DR and the RP.

· The path for a multicast packet might not be the shortest one.

· The RP might be overloaded by multicast traffic bursts.

To eliminate these weaknesses, PIM-SM allows an RP or the receiver-side DR to initiate the switchover to SPT.

· The RP initiates the switchover to SPT:

After receiving the first (S, G) multicast packet, the RP sends an (S, G) source-specific join message toward the multicast source immediately. The routers along the path from the RP to the multicast source constitute an SPT. The subsequent multicast packets are forwarded to the RP along the SPT without being encapsulated into register messages.

For more information about the switchover to SPT initiated by the RP, see "Multicast source registration."

· The receiver-side DR initiates the switchover to SPT:

After receiving the first (S, G) multicast packet, the receiver-side DR initiates the switchover to SPT immediately, as follows:

a. The receiver-side DR sends an (S, G) source-specific join message toward the multicast source. The routers along the path create an (S, G) entry in their forwarding table to constitute an SPT branch.

b. When the multicast packets reach the router where the RPT and the SPT branches, the router drops the multicast packets that travel along the RPT. It then sends a prune message with the RP bit to the RP.

c. After receiving the prune message, the RP forwards it toward the multicast source (supposed only one receiver exists). Thus, the switchover to SPT is completed. The subsequent multicast packets travel along the SPT from the multicast source to the receiver hosts.

With the switchover to SPT, PIM-SM builds SPTs more economically than PIM-DM does.

Assert

PIM-SM uses the same assert mechanism as PIM-DM does. For more information, see "Assert."

Administrative scoping overview

Typically, a PIM-SM domain contains only one BSR, which is responsible for advertising RP-set information within the entire PIM-SM domain. The information about all multicast groups is forwarded within the network that the BSR administers. This is called the "non-scoped BSR mechanism."

Administrative scoping mechanism

To implement refined management, you can divide a PIM-SM domain into a global-scoped zone and multiple administratively-scoped zones (admin-scoped zones). This is called the "administrative scoping mechanism."

The administrative scoping mechanism effectively releases stress on the management in a single-BSR domain and enables provision of zone-specific services through private group addresses.

Admin-scoped zones are divided for multicast groups. Zone border routers (ZBRs) form the boundary of an admin-scoped zone. Each admin-scoped zone maintains one BSR for multicast groups within a specific range. Multicast protocol packets, such as assert messages and BSMs, for a specific group range cannot cross the boundary of the admin-scoped zone for the group range. Multicast group ranges that are associated with different admin-scoped zones can have intersections. However, the multicast groups in an admin-scoped zone are valid only within the local zone, and theses multicast groups are regarded as private group addresses.

The global-scoped zone maintains a BSR for the multicast groups that do not belong to any admin-scoped zones.

Relationship between admin-scoped zones and the global-scoped zone

The global-scoped zone and each admin-scoped zone have their own C-RPs and BSRs. These devices are effective only on their respective zones, and the BSR election and the RP election are implemented independently. Each admin-scoped zone has its own boundary. The multicast information within a zone cannot cross this boundary in either direction. You can have a better understanding of the global-scoped zone and admin-scoped zones based on geographical locations and multicast group address ranges.

· In view of geographical locations:

An admin-scoped zone is a logical zone for particular multicast groups. The multicast packets for such multicast groups are confined within the local admin-scoped zone and cannot cross the boundary of the zone.

Figure 7 Relationship in view of geographical locations

As shown in Figure 7, for the multicast groups in a specific group address range, the admin-scoped zones must be geographically separated and isolated. A router cannot belong to multiple admin-scoped zones. An admin-scoped zone contains routers that are different from other admin-scoped zones. However, the global-scoped zone includes all routers in the PIM-SM domain. Multicast packets that do not belong to any admin-scoped zones are forwarded in the entire PIM-SM domain.

· In view of multicast group address ranges:

Each admin-scoped zone is designated to specific multicast groups, of which the multicast group addresses are valid only within the local zone. The multicast groups of different admin-scoped zones might have intersections. All the multicast groups other than those of the admin-scoped zones use the global-scoped zone.

Figure 8 Relationship in view of multicast group address ranges

As shown in Figure 8, the admin-scoped zones 1 and 2 have no intersection, but the admin-scoped zone 3 is a subset of the admin-scoped zone 1. The global-scoped zone provides services for all the multicast groups that are not covered by the admin-scoped zones 1 and 2, G−G1−G2 in this case.

PIM-SSM overview

The ASM model includes PIM-DM and PIM-SM. The SSM model can be implemented by leveraging part of the PIM-SM technique. It is also called "PIM-SSM."

The SSM model provides a solution for source-specific multicast. It maintains the relationship between hosts and routers through IGMPv3.

In actual applications, part of IGMPv3 and PIM-SM techniques are adopted to implement the SSM model. In the SSM model, because receivers have located a multicast source, no RP or RPT is required and multicast sources do not register for discovering multicast sources in other PIM domains.

Neighbor discovery

PIM-SSM uses the same neighbor discovery mechanism as PIM-SM. For more information, see "Neighbor discovery."

DR election

PIM-SSM uses the same DR election mechanism as PIM-SM. For more information, see "DR election."

SPT building

The decision to build an RPT for PIM-SM or an SPT for PIM-SSM depends on whether the multicast group that the multicast receiver joins is in the SSM group range. The SSM group range reserved by IANA is 232.0.0.0/8.

Figure 9 SPT building in PIM-SSM

As shown in Figure 9, Host B and Host C are receivers. They send IGMPv3 report messages to their DRs to express their interest in the multicast information that the multicast source S sends to the multicast group G.

After receiving a report message, the DR first checks whether the group address in this message is in the SSM group range and does the following:

· If the group address is in the SSM group range, the PIM-SSM service is provided.

The DR sends a subscribe message toward the multicast source. All routers along the path from the DR to the source create an (S, G) entry to build an SPT. The SPT is rooted at the multicast source and has the receivers as its leaves.

· If the group address is not in the SSM group range, the PIM-SM service is provided.

The receiver-side DR sends a (*, G) join message to the RP, and the multicast source registers with the source-side DR.

In PIM-SSM, the term "channel" refers to a multicast group, and the term "subscribe message" refers to a join message.

PIM support for VPNs

To support PIM for VPNs, a multicast router that runs PIM maintains an independent set of PIM neighbor table, multicast routing table, BSR information, and RP-set information for each VPN.

After receiving a multicast data packet, the multicast router checks to which VPN the data packet belongs. Then, the router forwards the packet according to the multicast routing table for that VPN or creates a multicast routing entry for that VPN.

Protocols and standards

· RFC 3973, Protocol Independent Multicast-Dense Mode (PIM-DM): Protocol Specification(Revised)

· RFC 4601, Protocol Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification (Revised)

· RFC 5059, Bootstrap Router (BSR) Mechanism for Protocol Independent Multicast (PIM)

· RFC 4607, Source-Specific Multicast for IP

· Draft-ietf-ssm-overview-05, An Overview of Source-Specific Multicast (SSM)

Configuring PIM-DM

This section describes how to configure PIM-DM.

PIM-DM configuration task list

Tasks at a glance
(Required.) Enabling PIM-DM
(Optional.) Enabling the state refresh feature
(Optional.) Configuring state refresh parameters
(Optional.) Configuring PIM-DM graft retry timer
(Optional.) Configuring common PIM features

Configuration prerequisites

Before you configure PIM-DM, configure a unicast routing protocol so that all devices in the domain are interoperable at the network layer

Enabling PIM-DM

Enable IP multicast routing before you configure PIM.

With PIM-DM enabled on interfaces, routers can establish PIM neighbor relationship and process PIM messages from their PIM neighbors. As a best practice, enable PIM-DM on all non-border interfaces of the routers when you deploy a PIM-DM domain.

IMPORTANT:

All the interfaces on a device must operate in the same PIM mode in the public network or the same VPN instance.

To enable PIM-DM:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable IP multicast routing and enter MRIB view.	multicast routing [ vpn-instance vpn-instance-name ]	By default, IP multicast routing is disabled.
3. Return to system view.	quit	N/A
4. Enter interface view.	interface interface-type interface-number	N/A
5. Enable PIM-DM.	pim dm	By default, PIM-DM is disabled.

Enabling the state refresh feature

In a PIM-DM domain, the state refresh feature enables the PIM router that is directly connected to the source to periodically send state refresh messages. It also enables other PIM routers to refresh pruned state timers after receiving the state refresh messages. It prevents the pruned interfaces from resuming multicast forwarding. You must enable this feature on all PIM routers on a subnet.

To enable the state refresh feature on all routers in PIM-DM domain:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Enable the state refresh feature.	pim state-refresh-capable	By default, the state refresh feature is enabled.

Configuring state refresh parameters

The router directly connected with the multicast source periodically sends state refresh messages. You can configure the interval for sending such messages on that router.

A router might receive duplicate state refresh messages within a short time. To prevent this situation, you can configure the amount of time that the router must wait before it receives next state refresh message. If the router receives a new state refresh message within the specified waiting time, it discards the message. If this timer times out, the router accepts a new state refresh message, refreshes its own PIM-DM state, and resets the waiting timer.

The TTL value of a state refresh message decrements by 1 whenever it passes a router before it is forwarded to the downstream node. The state refresh message stops being forwarded when the TTL value comes down to 0. A state refresh message with a large TTL value might cycle on a small network. To effectively control the propagation scope of state refresh messages, configure an appropriate TTL value based on the network size on the router directly connected with the multicast source.

To configure state refresh parameters:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Configure the interval to send state refresh messages.	state-refresh-interval interval	The default setting is 60 seconds.
4. Configure the time to wait before receiving a new state refresh message.	state-refresh-rate-limit time	The default setting is 30 seconds.
5. Configure the TTL value of state refresh messages.	state-refresh-ttl ttl-value	The default setting 255.

Configuring PIM-DM graft retry timer

To configure the graft retry timer:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Configure the graft retry timer.	pim timer graft-retry interval	The default setting is 3 seconds.

For more information about the configuration of other timers in PIM-DM, see "Configuring common PIM timers."

Configuring PIM-SM

This section describes how to configure PIM-SM.

PIM-SM configuration task list

Tasks at a glance	Remarks
(Required.) Enabling PIM-SM	N/A
(Required.) Configuring an RP: · Configuring a static RP · Configuring a C-RP · (Optional.) Enabling Auto-RP listening	You must configure a static RP, a C-RP, or both in a PIM-SM domain.
Configure a BSR: · (Required.) Configuring a C-BSR · (Optional.) Configuring a PIM domain border · (Optional.) Disabling BSM semantic fragmentation	Skip the task of configuring a BSR in a network without C-RPs.
(Optional.) Configuring multicast source registration	N/A
(Optional.) Configuring the switchover to SPT	N/A
(Optional.) Configuring common PIM features	N/A

Configuration prerequisites

Before you configure PIM-SM, configure a unicast routing protocol so that all devices in the domain are interoperable at the network layer.

Enabling PIM-SM

Enable IP multicast routing before you configure PIM.

With PIM-SM enabled on interfaces, routers can establish PIM neighbor relationship and process PIM messages from their PIM neighbors. As a best practice, enable PIM-SM on all non-border interfaces of routers when you deploy a PIM-SM domain.

IMPORTANT:

All the interfaces on the same router must operate in the same PIM mode in the public network or the same VPN instance.

To enable PIM-SM:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable IP multicast routing and enter MRIB view.	multicast routing [ vpn-instance vpn-instance-name ]	By default, IP multicast routing is disabled.
3. Return to system view.	quit	N/A
4. Enter interface view.	interface interface-type interface-number	N/A
5. Enable PIM-SM.	pim sm	By default, PIM-SM is disabled.

Configuring an RP

An RP can provide services for multiple or all multicast groups. However, only one RP can forward multicast traffic for a multicast group at a moment.

An RP can be manually configured or dynamically elected through the BSR mechanism. For a large-scaled PIM network, configuring static RPs is a tedious job. Generally, static RPs are backups for dynamic RPs to enhance the robustness and operational manageability on a multicast network.

Configuring a static RP

If only one dynamic RP exists on a network, you can configure a static RP to avoid communication interruption caused by single-point failures. The static RP also prevents frequent message exchange between C-RPs and the BSR for RP election.

When you configure static RPs for PIM-SM, follow these restrictions and guidelines:

· You can configure the same static RP for different multicast groups by using the same RP address but different ACLs.

· You do not need to enable PIM for an interface to be configured as a static RP.

· If you configure multiple static RPs for a multicast group, only the static RP with the highest IP address takes effect.

· The static RP configuration must be the same on all routers in the PIM-SM domain.

To configure a static RP for PIM-SM:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Configure a static RP for PIM-SM.	static-rp rp-address [ acl-number \| preferred ] *	By default, no static RPs exist.

Configuring a C-RP

IMPORTANT:

When you configure a C-RP, reserve a relatively large bandwidth between the C-RP and other devices in the PIM-SM domain.

In a PIM-SM domain, if you want a router to become the RP, you can configure the router as a C-RP. As a best practice, configure C-RPs on backbone routers.

The C-RPs periodically send advertisement messages to the BSR, which collects RP set information. You can configure the interval for sending the advertisement messages.

The holdtime option in C-RP advertisement messages defines the C-RP lifetime for the advertising C-RP. The BSR starts a holdtime timer for a C-RP after the BSR receives an advertisement message. If the BSR does not receive any advertisement message when the timer expires, it regards the C-RP failed or unreachable.

A C-RP policy enables the BSR to filter C-RP advertisement messages by using an ACL that specifies the packet source addresses and multicast groups. It is used to guard against C-RP spoofing. You must configure the same C-RP policy on all C-BSRs in the PIM-SM domain.

To configure a C-RP:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Configure a C-RP.	c-rp ip-address [ advertisement-interval adv-interval \| group-policy acl-number \| holdtime hold-time \| priority priority ] *	By default, no C-RPs exist.
4. (Optional.) Configure a C-RP policy.	crp-policy acl-number	By default, no C-RP policy exists.

Enabling Auto-RP listening

This feature enables the router to receive Auto-RP announcement and discovery messages and learn RP information. The destination IP addresses for Auto-RP announcement and discovery messages are 224.0.1.39 and 224.0.1.40, respectively.

To enable Auto-RP listening:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Enable Auto-RP listening.	auto-rp enable	By default, Auto-RP listening is disabled.

Configuring a BSR

You must configure a BSR if C-RPs are configured to dynamically select the RP. You do not need to configure a BSR when you have configured only a static RP but no C-RPs.

A PIM-SM domain can have only one BSR, but must have a minimum of one C-BSR. Any router can be configured as a C-BSR. Elected from C-BSRs, the BSR is responsible for collecting and advertising RP information in the PIM-SM domain.

Configuring a C-BSR

The BSR election process is summarized as follows:

1. Initially, each C-BSR regards itself as the BSR of the PIM-SM domain and sends BSMs to other routers in the domain.

2. When a C-BSR receives the BSM from another C-BSR, it compares its own priority with the priority carried in the message. The C-BSR with a higher priority wins the BSR election. If a tie exists in the priority, the C-BSR with a higher IP address wins. The loser uses the winner's BSR address to replace its own BSR address and no longer regards itself as the BSR, and the winner retains its own BSR address and continues to regard itself as the BSR.

The elected BSR distributes the RP-set information collected from C-RPs to all routers in the PIM-SM domain. All routers use the same hash algorithm to get an RP for a specific multicast group.

A BSR policy enables a PIM-SM router to filter BSR messages by using an ACL that specifies the legal BSR addresses. It is used to guard against the following BSR spoofing cases:

· Some maliciously configured hosts can forge BSMs to fool routers and change RP mappings. Such attacks often occur on border routers.

· When an attacker controls a router on the network, the attacker can configure the router as a C-BSR to win the BSR election. Through this router, the attacker controls the advertising of RP information.

When you configure a C-BSR, follow these guidelines:

· Configure C-BSRs on routers that are on the backbone network.

· Reserve a relatively large bandwidth between the C-BSR and the other devices in the PIM-SM domain.

· You must configure the same BSR policy on all routers in the PIM-SM domain. The BSR policy discards illegal BSR messages, but it partially guards against BSR attacks on the network. If an attacker controls a legal BSR, the problem still exists.

To configure a C-BSR:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Configure a C-BSR.	c-bsr ip-address [ scope group-address { mask-length \| mask } ] [ hash-length hash-length \| priority priority ] *	By default, no C-BSRs exist.
4. (Optional.) Configure a BSR policy.	bsr-policy acl-number	By default, no BSR policy exists.

Configuring a PIM domain border

A PIM domain border determines the transmission boundary of bootstrap messages. Bootstrap messages cannot cross the domain border in either direction. A number of PIM domain border interfaces partition a network into different PIM-SM domains.

To configure a PIM domain border:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Configure a PIM domain border.	pim bsr-boundary	By default, no PIM domain border exists.

Disabling BSM semantic fragmentation

BSM semantic fragmentation enables a BSR to split a BSM into several BSM fragments (BSMF) if the BSM exceeds the MTU. In this way, a non-BSR router can update the RP-set information for a group range after receiving all BSMFs for the group range. The loss of one BSMF only affects the RP-set information of the group ranges that the fragment contains.

BSM semantic fragmentation is enabled by default. A device that does not support this feature might regard a fragment as an entire BSM and thus learns only part of the RP-set information. If such devices exist in the PIM-SM domain, you must disable BSM semantic fragmentation on the C-BSRs.

To disable BSM semantic fragmentation:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Disable BSM semantic fragmentation.	undo bsm-fragment enable	By default, BSM semantic fragmentation is enabled.

NOTE:

Generally, a BSR performs BSM semantic fragmentation according to the MTU of its BSR interface. For BSMs originated due to learning of a new PIM neighbor, semantic fragmentation is performed according to the MTU of the interface that sends the BSMs.

Configuring multicast source registration

A PIM register policy enables an RP to filter register messages by using an ACL that specifies the multicast sources and groups. The policy limits the multicast groups to which the RP is designated. If a register message is denied by the ACL or does not match the ACL, the RP discards the register message and sends a register-stop message to the source-side DR. The registration process stops.

You can configure the switch to calculate the checksum based on the entire register message to ensure information integrity of a register message in the transmission process. If a device that does not support this feature is present on the network, configure the switch to calculate the checksum based on the register message header.

To configure multicast source registration:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Configure a PIM register policy.	register-policy acl-number	By default, no PIM register policy exists.
4. Configure the switch to calculate the checksum based on the entire register message.	register-whole-checksum	By default, the switch calculates the checksum based on the header of a register message.

Configuring the switchover to SPT

CAUTION:

If the switch is an RP, disabling the switchover to SPT might cause multicast traffic forwarding failures on the source-side DR. When disabling the switchover to SPT, make sure you fully understand its impact on your network.

To configure the switchover to SPT:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Configure the RPT to SPT switchover.	spt-switch-threshold { immediacy \| infinity } [ group-policy acl-number ]	By default, the first multicast data packet triggers the RPT to SPT switchover.

Configuring PIM-SSM

PIM-SSM requires IGMPv3 support. Enable IGMPv3 on PIM routers that connect to multicast receivers.

PIM-SSM configuration task list

Tasks at a glance
(Required.) Enabling PIM-SM
(Optional.) Configuring the SSM group range
(Optional.) Configuring common PIM features

Configuration prerequisites

Before you configure PIM-SSM, configure a unicast routing protocol so that all devices in the domain are interoperable at the network layer.

Enabling PIM-SM

The implementation of the SSM model is based on subsets of PIM-SM. Therefore, you must enable PIM-SM before configuring PIM-SSM.

When you deploy a PIM-SSM domain, enable PIM-SM on non-border interfaces of the routers.

IMPORTANT:

All the interfaces on a device must be enabled with the same PIM mode.

To enable PIM-SM:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable IP multicast routing, and enter MRIB view.	multicast routing [ vpn-instance vpn-instance-name ]	By default, IP multicast routing is disabled.
3. Return to system view.	quit	N/A
4. Enter interface view.	interface interface-type interface-number	N/A
5. Enable PIM-SM.	pim sm	By default, PIM-SM is disabled.

Configuring the SSM group range

When a PIM-SM enabled interface receives a multicast packet, it checks whether the multicast group address of the packet is in the SSM group range. If the multicast group address is in this range, the PIM mode for this packet is PIM-SSM. If the multicast group address is not in this range, the PIM mode is PIM-SM.

Configuration guidelines

When you configure the PIM-SSM group range, follow these guidelines:

· Configure the same SSM group range is configured on all routers in the entire PIM-SSM domain. Otherwise, multicast information cannot be delivered through the SSM model.

· When a member of a multicast group in the SSM group range sends an IGMPv1 or IGMPv2 report message, the switch does not trigger a (*, G) join.

Configuration procedure

To configure an SSM group range:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim	N/A
3. Configure the SSM group range.	ssm-policy acl-number	The default range is 232.0.0.0/8.

Configuring common PIM features

Configuration task list

Tasks at a glance
(Optional.) Configuring a multicast source policy
(Optional.) Configuring a PIM hello policy
(Optional.) Configuring PIM hello message options
(Optional.) Configuring common PIM timers
(Optional.) Setting the maximum size of each join or prune message
(Optional.) Enabling BFD for PIM
(Optional.) Enabling PIM passive mode

Configuration prerequisites

Before you configure common PIM features, complete the following tasks:

· Configure a unicast routing protocol so that all devices in the domain are interoperable at the network layer.

· Configure PIM-DM, or PIM-SM.

Configuring a multicast source policy

This feature enables the switch to filter multicast data by using an ACL that specifies the multicast sources and the optional groups. It filters not only data packets but also register messages with multicast data encapsulated. It controls the information available to downstream receivers.

To configure a multicast source policy:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Configure a multicast source policy:	source-policy acl-number	By default, no multicast source policy exists.

Configuring a PIM hello policy

This feature enables the switch to filter PIM hello messages by using an ACL that specifies the packet source addresses. It is used to guard against PIM message attacks and to establish correct PIM neighboring relationships.

To configure a PIM hello policy:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Configure a PIM hello policy.	pim neighbor-policy acl-number	By default, no PIM hello policy exists. If a PIM neighbor's hello messages cannot pass the policy, the neighbor is automatically removed when its maximum number of hello attempts is reached.

Configuring PIM hello message options

In either a PIM-DM domain or a PIM-SM domain, hello messages exchanged among routers contain the following configurable options:

· DR_Priority (for PIM-SM only)—Priority for DR election. The device with the highest priority wins the DR election. You can configure this option for all the routers in a shared-media LAN that directly connects to the multicast source or the receivers.

· Holdtime—PIM neighbor lifetime. If a router does not receive a hello message from a neighbor when the neighbor lifetime timer expires, it regards the neighbor failed or unreachable.

· LAN_Prune_Delay—Delay of pruning a downstream interface on a shared-media LAN. This option has LAN delay, override interval, and neighbor tracking support (namely, the capability to disable join message suppression).

The LAN delay defines the PIM message propagation delay. The override interval defines a period for a router to override a prune message. If the propagation delay or override interval on different PIM routers on a shared-media LAN are different, the largest ones apply.

On a shared-media LAN, the propagation delay and override interval are used as follows:

¡ If a router receives a prune message on its upstream interface, it means that there are downstream routers on the shared-media LAN. If this router still needs to receive multicast data, it must send a join message to override the prune message within the override interval.

¡ When a router receives a prune message from its downstream interface, it does not immediately prune this interface. Instead, it starts a timer (the propagation delay plus the override interval). If interface receives a join message before the timer expires, the router does not prune the interface. Otherwise, the router prunes the interface.

You can enable neighbor tracking on an upstream router to track the states of the downstream nodes for which the joined state holdtime timer has not expired. If you want to enable neighbor tracking, you must enable it on all PIM routers on a shared-media LAN. Otherwise, the upstream router cannot track join messages from every downstream routers.

· Generation ID—A router generates a generation ID for hello messages when an interface is enabled with PIM. The generation ID is a random value, but only changes when the status of the router changes. If a PIM router finds that the generation ID in a hello message from the upstream router has changed, it assumes that the status of the upstream router has changed. In this case, it sends a join message to the upstream router for status update. You can configure an interface to drop hello messages without the generation ID options to promptly know the status of an upstream router.

You can configure hello message options for all interfaces in PIM view or for the current interface in interface view. The configuration made in interface view takes priority over the configuration made in PIM view.

Configuring hello message options globally

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Set the DR priority.	hello-option dr-priority priority	The default setting is 1.
4. Set the neighbor lifetime.	hello-option holdtime time	The default setting is 105 seconds.
5. Set the PIM message propagation delay.	hello-option lan-delay delay	The default setting is 500 milliseconds.
6. Set the override interval.	hello-option override-interval interval	The default setting is 2500 milliseconds.
7. Enable neighbor tracking.	hello-option neighbor-tracking	By default, neighbor tracking is disabled.

Configuring hello message options on an interface

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Set the DR priority.	pim hello-option dr-priority priority	The default setting is 1.
4. Set the neighbor lifetime.	pim hello-option holdtime time	The default setting is 105 seconds.
5. Set the PIM message propagation delay.	pim hello-option lan-delay delay	The default setting is 500 milliseconds.
6. Set the override interval.	pim hello-option override-interval interval	The default setting is 2500 milliseconds.
7. Enable neighbor tracking.	pim hello-option neighbor-tracking	By default, neighbor tracking is disabled.
8. Enable dropping hello messages without the Generation ID option.	pim require-genid	By default, an interface accepts hello messages without the Generation ID option.

Configuring common PIM timers

CAUTION:

To prevent the upstream neighbors from aging out, you must configure the interval for sending join/prune message less than the joined/pruned state holdtime timer.

The following are common timers in PIM:

· Hello interval—Interval at which a PIM router sends hello messages to discover PIM neighbors and to maintain PIM neighbor relationship.

· Triggered hello delay—Maximum delay for sending a hello message to avoid collisions caused by simultaneous hello messages. After receiving a hello message, a PIM router waits for a random time before sending a hello message. This random time is in the range of 0 to the triggered hello delay.

· Join/Prune interval—Interval at which a PIM router sends join/prune messages to its upstream routers for state update.

· Joined/Pruned state holdtime—Time for which a PIM router keeps the joined/pruned state for the downstream interfaces. This joined/pruned state holdtime is specified in a join/prune message.

· Multicast source lifetime—Lifetime that a PIM router maintains for a multicast source. If the router does not receive subsequent multicast data from the multicast source S when the timer expires, it deletes the (S, G) entry for the multicast source.

You can configure common PIM timers for all interfaces in PIM view or for the current interface in interface view. The configuration made in interface view takes priority over the configuration made in PIM view.

TIP:

As a best practice, use the default settings for a network without special requirements.

Configuring common PIM timers globally

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Set the hello interval.	timer hello interval	The default setting is 30 seconds.
4. Set the join/prune interval.	timer join-prune interval	The default setting is 60 seconds. NOTE: This configuration takes effect after the current interval ends.
5. Set the joined/pruned state holdtime.	holdtime join-prune time	The default setting is 210 seconds.
6. Set the multicast source lifetime.	source-lifetime time	The default setting is 210 seconds.

Configuring common PIM timers on an interface

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Set the hello interval.	pim timer hello interval	The default setting is 30 seconds.
4. Set the triggered hello delay.	pim triggered-hello-delay delay	The default setting is 5 seconds.
5. Set the join/prune interval.	pim timer join-prune interval	The default setting is 60 seconds. NOTE: This configuration takes effect after the current interval ends.
6. Set the joined/pruned state holdtime.	pim holdtime join-prune time	The default setting is 210 seconds.

Setting the maximum size of each join or prune message

The loss of an oversized join or prune message might result in loss of massive information. You can set a small value for the size of each join or prune message to reduce the impact.

To set the maximum size of each join or prune message:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter PIM view.	pim [ vpn-instance vpn-instance-name ]	N/A
3. Set the maximum size of each join or prune message.	jp-pkt-size size	The default setting is 8100 bytes.

Enabling BFD for PIM

If the DR on a shared-media network fails, a new DR election process will start after the DR ages out. However, it might take a long period of time before other routers detect the link failures and trigger a new DR election. To start a new DR election process immediately after the original DR fails, enable BFD for PIM on a shared-media network to detect link failures among PIM neighbors.

You must enable BFD for PIM on all PIM-capable routers on a shared-media network. For more information about BFD, see High Availability Configuration Guide.

You must enable PIM-DM or PIM-SM on an interface before you configure this feature.

To enable BFD for PIM:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Enable BFD for PIM.	pim bfd enable	By default, BFD is disabled for PIM.

Enabling PIM passive mode

To guard against PIM hello spoofing, you can enable PIM passive mode on an interface which is directly connected to user hosts. The PIM passive interface cannot receive or forward PIM protocol messages (excluding register, register-stop and C-RP-Adv messages), and it acts as the DR on the subnet. In BIDIR-PIM, it also acts as the DF.

Configuration guidelines

When you enable PIM passive mode, follow these restrictions and guidelines:

· This feature takes effect only when PIM-DM or PIM-SM is enabled on the interface.

· Do not enable this feature on a shared-media LAN with multiple PIM routers. If you do this, the PIM passive interface might become a second DR and DF on the subnet. This will cause duplicate data and flow loop.

Configuration procedure

To enable PIM passive mode on an interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Enable PIM passive mode on the interface.	pim passive	By default, PIM passive mode is disabled.

Displaying and maintaining PIM

Execute display commands in any view.

Task	Command
Display register-tunnel interface information.	display interface [ register-tunnel [ interface-number ] ] [ brief [ description \| down ] ]
Display BSR information in the PIM-SM domain.	display pim [ vpn-instance vpn-instance-name ] bsr-info
Display information about the routes used by PIM.	display pim [ vpn-instance vpn-instance-name ] claimed-route [ source-address ]
Display C-RP information in the PIM-SM domain.	display pim [ vpn-instance vpn-instance-name ] c-rp [ local ]
Display PIM information on an interface.	display pim [ vpn-instance vpn-instance-name ] interface [ interface-type interface-number ] [ verbose ]
Display PIM neighbor information.	display pim [ vpn-instance vpn-instance-name ] neighbor [ neighbor-address \| interface interface-type interface-number \| verbose ] *
Display information about PIM routing entries.	display pim [ vpn-instance vpn-instance-name ] routing-table [ group-address [ mask { mask-length \| mask } ] \| source-address [ mask { mask-length \| mask } ] \| flags flag-value \| fsm \| incoming-interface interface-type interface-number \| mode mode-type \| outgoing-interface { exclude \| include \| match } interface-type interface-number ] *
Display RP information in the PIM-SM domain.	display pim [ vpn-instance vpn-instance-name ] rp-info [ group-address ]
Display statistics for PIM packets.	display pim statistics

PIM configuration examples

PIM-DM configuration example

Network requirements

As shown in Figure 10:

· VOD streams are sent to receiver hosts in multicast. The receiver groups of different organizations form stub networks, and one or more receiver hosts exist in each stub network.

· The entire PIM domain operates in the dense mode.

· Host A and Host C are multicast receivers in two stub networks.

· IGMPv2 runs between Switch A and N1 and between Switch B, Switch C, and N2.

Figure 10 Network diagram

Table 1 Interface and IP address assignment

Device	Interface	IP address	Device	Interface	IP address
Switch A	Vlan-int100	10.110.1.1/24	Switch C	Vlan-int102	192.168.3.1/24
Switch A	Vlan-int103	192.168.1.1/24	Switch D	Vlan-int300	10.110.5.1/24
Switch B	Vlan-int200	10.110.2.1/24	Switch D	Vlan-int103	192.168.1.2/24
Switch B	Vlan-int101	192.168.2.1/24	Switch D	Vlan-int101	192.168.2.2/24
Switch C	Vlan-int200	10.110.2.2/24	Switch D	Vlan-int102	192.168.3.2/24

Configuration procedure

1. Assign an IP address and subnet mask to each interface according to Figure 10. (Details not shown.)

2. Configure OSPF on the switches in the PIM-DM domain to make sure the following conditions are met: (Details not shown.)

¡ The switches are interoperable at the network layer.

¡ The switches can dynamically update their routing information.

3. Enable IP multicast routing, IGMP, and PIM-DM:

# On Switch A, enable IP multicast routing.

<SwitchA> system-view

[SwitchA] multicast routing

[SwitchA-mrib] quit

# Enable IGMP on the receiver-side interface (VLAN-interface 100).

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] igmp enable

[SwitchA-Vlan-interface100] quit

# Enable PIM-DM on VLAN-interface 103.

[SwitchA] interface vlan-interface 103

[SwitchA-Vlan-interface103] pim dm

[SwitchA-Vlan-interface103] quit

# Enable IP multicast routing, IGMP, and PIM-DM on Switch B and Switch C in the same way Switch A is configured. (Details not shown.)

# On Switch D, enable IP multicast routing, and enable PIM-DM on each interface.

<SwitchD> system-view

[SwitchD] multicast routing

[SwitchD-mrib] quit

[SwitchD] interface vlan-interface 300

[SwitchD-Vlan-interface300] pim dm

[SwitchD-Vlan-interface300] quit

[SwitchD] interface vlan-interface 103

[SwitchD-Vlan-interface103] pim dm

[SwitchD-Vlan-interface103] quit

[SwitchD] interface vlan-interface 101

[SwitchD-Vlan-interface101] pim dm

[SwitchD-Vlan-interface101] quit

[SwitchD] interface vlan-interface 102

[SwitchD-Vlan-interface102] pim dm

[SwitchD-Vlan-interface102] quit

Verifying the configuration

# Display PIM information on Switch D.

[SwitchD] display pim interface

Interface NbrCnt HelloInt DR-Pri DR-Address

Vlan300 0 30 1 10.110.5.1 (local)

Vlan103 1 30 1 192.168.1.2 (local)

Vlan101 1 30 1 192.168.2.2 (local)

Vlan102 1 30 1 192.168.3.2 (local)

# Display PIM neighboring relationships on Switch D.

[SwitchD] display pim neighbor

Total Number of Neighbors = 3

Neighbor Interface Uptime Expires Dr-Priority

192.168.1.1 Vlan103 00:02:22 00:01:27 1

192.168.2.1 Vlan101 00:00:22 00:01:29 3

192.168.3.1 Vlan102 00:00:23 00:01:31 5

# Send an IGMP report from Host A to join multicast group 225.1.1.1. (Details not shown.)

# Send multicast data from multicast source 10.110.5.100 to multicast group 225.1.1.1. (Details not shown).

# Display the PIM routing table information on Switch A.

[SwitchA] display pim routing-table

Total 1 (*, G) entry; 1 (S, G) entry

(*, 225.1.1.1)

Protocol: pim-dm, Flag: WC

UpTime: 00:04:25

Upstream interface: NULL

Upstream neighbor: NULL

RPF prime neighbor: NULL

Downstream interface(s) information:

Total number of downstreams: 1

1: Vlan-interface100

Protocol: igmp, UpTime: 00:04:25, Expires: -

(10.110.5.100, 225.1.1.1)

Protocol: pim-dm, Flag: ACT

UpTime: 00:06:14

Upstream interface: Vlan-interface103

Upstream neighbor: 192.168.1.2

RPF prime neighbor: 192.168.1.2

Downstream interface(s) information:

Total number of downstreams: 1

1: Vlan-interface100

Protocol: pim-dm, UpTime: 00:04:25, Expires: -

# Display the PIM routing table information on Switch D.

[SwitchD] display pim routing-table

Total 0 (*, G) entry; 1 (S, G) entry

(10.110.5.100, 225.1.1.1)

Protocol: pim-dm, Flag: LOC ACT

UpTime: 00:03:27

Upstream interface: Vlan-interface300

Upstream neighbor: NULL

RPF prime neighbor: NULL

Downstream interface(s) information:

Total number of downstreams: 2

1: Vlan-interface103

Protocol: pim-dm, UpTime: 00:03:27, Expires: -

2: Vlan-interface102

Protocol: pim-dm, UpTime: 00:03:27, Expires: -

The output shows the following information:

· Switches on the SPT path (Switch A and Switch D) have the correct (S, G) entries.

· Switch A has the correct (*, G) entry.

PIM-SM non-scoped zone configuration example

Network requirements

As shown in Figure 11:

· VOD streams are sent to receiver hosts in multicast. The receivers of different subnets form stub networks, and a minimum of one receiver host exist in each stub network. The entire PIM-SM domain contains only one BSR.

· Host A and Host C are multicast receivers in two stub networks N1 and N2.

· Both VLAN-interface 105 on Switch D and VLAN-interface 102 on Switch E act as C-BSRs and C-RPs. The C-BSR on Switch E has a higher priority. The C-RPs are designated to the multicast group range 225.1.1.0/24. Modify the hash mask length to map the multicast group range to the two C-RPs.

· IGMPv2 runs between Switch A and N1, and between Switch B, Switch C, and N2.

Figure 11 Network diagram

Table 2 Interface and IP address assignment

Device	Interface	IP address	Device	Interface	IP address
Switch A	Vlan-int100	10.110.1.1/24	Switch D	Vlan-int300	10.110.5.1/24
Switch A	Vlan-int101	192.168.1.1/24	Switch D	Vlan-int101	192.168.1.2/24
Switch A	Vlan-int102	192.168.9.1/24	Switch D	Vlan-int105	192.168.4.2/24
Switch B	Vlan-int200	10.110.2.1/24	Switch E	Vlan-int104	192.168.3.2/24
Switch B	Vlan-int103	192.168.2.1/24	Switch E	Vlan-int103	192.168.2.2/24
Switch C	Vlan-int200	10.110.2.2/24	Switch E	Vlan-int102	192.168.9.2/24
Switch C	Vlan-int104	192.168.3.1/24	Switch E	Vlan-int105	192.168.4.1/24

Configuration procedure

1. Assign an IP address and subnet mask to each interface according to Figure 11. (Details not shown.)

2. Enable OSPF on all switches on the PIM-SM network to make sure the following conditions are met: (Details not shown.)

¡ The switches are interoperable at the network layer.

¡ The switches can dynamically update their routing information.

3. Enable IP multicast routing, and enable IGMP and PIM-SM:

# On Switch A, enable IP multicast routing globally.

<SwitchA> system-view

[SwitchA] multicast routing

[SwitchA-mrib] quit

# Enable IGMP on the receiver-side interface (VLAN-interface 100).

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] igmp enable

[SwitchA-Vlan-interface100] quit

# Enable PIM-DM on the other interfaces.

[SwitchA] interface vlan-interface 101

[SwitchA-Vlan-interface101] pim sm

[SwitchA-Vlan-interface101] quit

[SwitchA] interface vlan-interface 102

[SwitchA-Vlan-interface102] pim sm

[SwitchA-Vlan-interface102] quit

# Enable IP multicast routing, IGMP, and PIM-SM on Switch B and Switch C in the same way Switch A is configured. (Details not shown.)

# Enable IP multicast routing and PIM-SM on Switch D and Switch E in the same way Switch A is configured. (Details not shown.)

4. Configure C-BSRs and C-RPs:

# On Switch D, configure the service scope of RP advertisements.

<SwitchD> system-view

[SwitchD] acl number 2005

[SwitchD-acl-basic-2005] rule permit source 225.1.1.0 0.0.0.255

[SwitchD-acl-basic-2005] quit

# Configure VLAN-interface 105 as a C-BSR and a C-RP, and set the hash mask length to 32 and the priority of the C-BSR to 10.

[SwitchD] pim

[SwitchD-pim] c-bsr 192.168.4.2 hash-length 32 priority 10

[SwitchD-pim] c-rp 192.168.4.2 group-policy 2005

[SwitchD-pim] quit

# On Switch E, configure the service scope of RP advertisements.

<SwitchE> system-view

[SwitchE] acl number 2005

[SwitchE-acl-basic-2005] rule permit source 225.1.1.0 0.0.0.255

[SwitchE-acl-basic-2005] quit

# Configure VLAN-interface 102 as a C-BSR and a C-RP, and set the hash mask length to 32 and the priority of the C-BSR to 20.

[SwitchE] pim

[SwitchE-pim] c-bsr 192.168.9.2 hash-length 32 priority 20

[SwitchE-pim] c-rp 192.168.9.2 group-policy 2005

[SwitchE-pim] quit

Verifying the configuration

# Display PIM information on Switch A.

[SwitchA] display pim interface

Interface NbrCnt HelloInt DR-Pri DR-Address

Vlan100 0 30 1 10.110.1.1 (local)

Vlan101 1 30 1 192.168.1.2

Vlan102 1 30 1 192.168.9.2

# Display BSR information on Switch A.

[SwitchA] display pim bsr-info

Scope: non-scoped

State: Accept Preferred

Bootstrap timer: 00:01:44

Elected BSR address: 192.168.9.2

Priority: 20

Hash mask length: 32

Uptime: 00:40:40

# Display BSR information on Switch D.

[SwitchD] display pim bsr-info

Scope: non-scoped

State: Candidate

Bootstrap timer: 00:01:44

Elected BSR address: 192.168.9.2

Priority: 20

Hash mask length: 32

Uptime: 00:05:26

Candidate BSR address: 192.168.4.2

Priority: 10

Hash mask length: 32

# Display BSR information on Switch E.

[SwitchE] display pim bsr-info

Scope: non-scoped

State: Elected

Bootstrap timer: 00:01:44

Elected BSR address: 192.168.9.2

Priority: 20

Hash mask length: 32

Uptime: 00:01:18

Candidate BSR address: 192.168.9.2

Priority: 20

Hash mask length: 32

# Display RP information on Switch A.

[SwitchA] display pim rp-info

BSR RP information:

Scope: non-scoped

Group/MaskLen: 225.1.1.0/24

RP address Priority HoldTime Uptime Expires

192.168.4.2 192 150 00:51:45 00:02:22

192.168.9.2 192 150 00:51:45 00:02:22

PIM-SM admin-scoped zone configuration example

Network requirements

As shown in Figure 12:

· VOD streams are sent to receiver hosts in multicast. The entire PIM-SM domain is divided into admin-scoped zone 1, admin-scoped zone 2, and the global-scoped zone. Switch B, Switch C, and Switch D are ZBRs of the three zones, respectively.

· Source 1 and Source 2 send different multicast data to multicast group 239.1.1.1. Host A receives the multicast data only from Source 1, and Host B receives the multicast data only from Source 2. Source 3 sends multicast data to multicast group 224.1.1.1. Host C is a multicast receiver for multicast group 224.1.1.1.

· VLAN-interface 101 of Switch B acts as a C-BSR and a C-RP for admin-scoped zone 1. VLAN-interface 105 of Switch D acts as a C-BSR and a C-RP for admin-scoped zone 2. Both of the two interfaces are designated to the multicast group range 239.0.0.0/8. VLAN-interface 109 of Switch F acts as a C-BSR and a C-RP for the global-scoped zone, and is designated to all the multicast groups that are not in the range 239.0.0.0/8.

· IGMPv2 runs between Switch A, Switch E, Switch I, and the receivers that directly connect to them, respectively.

Figure 12 Network diagram

Table 3 Interface and IP address assignment

Device	Interface	IP address	Device	Interface	IP address
Switch A	Vlan-int100	192.168.1.1/24	Switch D	Vlan-int105	10.110.5.2/24
Switch A	Vlan-int101	10.110.1.1/24	Switch D	Vlan-int108	10.110.7.1/24
Switch B	Vlan-int200	192.168.2.1/24	Switch D	Vlan-int107	10.110.8.1/24
Switch B	Vlan-int101	10.110.1.2/24	Switch E	Vlan-int400	192.168.4.1/24
Switch B	Vlan-int103	10.110.2.1/24	Switch E	Vlan-int104	10.110.4.2/24
Switch B	Vlan-int102	10.110.3.1/24	Switch E	Vlan-int108	10.110.7.2/24
Switch C	Vlan-int300	192.168.3.1/24	Switch F	Vlan-int109	10.110.9.1/24
Switch C	Vlan-int104	10.110.4.1/24	Switch F	Vlan-int107	10.110.8.2/24
Switch C	Vlan-int105	10.110.5.1/24	Switch F	Vlan-int102	10.110.3.2/24
Switch C	Vlan-int103	10.110.2.2/24	Switch G	Vlan-int500	192.168.5.1/24
Switch C	Vlan-int106	10.110.6.1/24	Switch G	Vlan-int109	10.110.9.2/24
Switch H	Vlan-int110	10.110.10.1/24	Source 1	—	192.168.2.10/24
Switch H	Vlan-int106	10.110.6.2/24	Source 2	—	192.168.3.10/24
Switch I	Vlan-int600	192.168.6.1/24	Source 3	—	192.168.5.10/24
Switch I	Vlan-int110	10.110.10.2/24

Configuration procedure

1. Assign an IP address and subnet mask to each interface according to Figure 12. (Details not shown.)

2. Configure OSPF on all switches on the PIM-SM network to make sure the following conditions are met: (Details not shown.)

¡ The switches are interoperable at the network layer.

¡ The switches can dynamically update their routing information.

3. Enable IP multicast routing, and enable IGMP and PIM-SM:

# On Switch A, enable IP multicast routing.

<SwitchA> system-view

[SwitchA] multicast routing

[SwitchA-mrib] quit

# Enable IGMP on the receiver-side interface (VLAN-interface 100).

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] igmp enable

[SwitchA-Vlan-interface100] quit

# Enable PIM-SM on VLAN-interface 101.

[SwitchA] interface vlan-interface 101

[SwitchA-Vlan-interface101] pim sm

[SwitchA-Vlan-interface101] quit

# Enable IP multicast routing, IGMP, and PIM-SM on Switch E and Switch I in the same way Switch A is configured. (Details not shown.)

# On Switch B, enable IP multicast routing, and enable PIM-SM on each interface.

<SwitchB> system-view

[SwitchB] multicast routing

[SwitchB-mrib] quit

[SwitchB] interface vlan-interface 200

[SwitchB-Vlan-interface200] pim sm

[SwitchB-Vlan-interface200] quit

[SwitchB] interface vlan-interface 101

[SwitchB-Vlan-interface101] pim sm

[SwitchB-Vlan-interface101] quit

[SwitchB] interface vlan-interface 102

[SwitchB-Vlan-interface102] pim sm

[SwitchB-Vlan-interface102] quit

[SwitchB] interface vlan-interface 103

[SwitchB-Vlan-interface103] pim sm

[SwitchB-Vlan-interface103] quit

# Enable IP multicast routing and PIM-SM on Switch C, Switch D, Switch F, Switch G, and Switch H in the same way Switch B is configured. (Details not shown.)

4. Configure admin-scoped zone boundaries:

# On Switch B, configure VLAN-interface 102 and VLAN-interface 103 as the boundaries of admin-scoped zone 1.

[SwitchB] interface vlan-interface 102

[SwitchB-Vlan-interface102] multicast boundary 239.0.0.0 8

[SwitchB-Vlan-interface102] quit

[SwitchB] interface vlan-interface 103

[SwitchB-Vlan-interface103] multicast boundary 239.0.0.0 8

[SwitchB-Vlan-interface103] quit

# On Switch C, configure VLAN-interface 103 and VLAN-interface 106 as the boundaries of admin-scoped zone 2.

<SwitchC> system-view

[SwitchC] interface vlan-interface 103

[SwitchC-Vlan-interface103] multicast boundary 239.0.0.0 8

[SwitchC-Vlan-interface103] quit

[SwitchC] interface vlan-interface 106

[SwitchC-Vlan-interface106] multicast boundary 239.0.0.0 8

[SwitchC-Vlan-interface106] quit

# On Switch D, configure VLAN-interface 107 as the boundary of admin-scoped zone 2.

<SwitchD> system-view

[SwitchD] interface vlan-interface 107

[SwitchD-Vlan-interface107] multicast boundary 239.0.0.0 8

[SwitchD-Vlan-interface107] quit

5. Configure C-BSRs and C-RPs:

# On Switch B, configure the service scope of RP advertisements.

[SwitchB] acl number 2001

[SwitchB-acl-basic-2001] rule permit source 239.0.0.0 0.255.255.255

[SwitchB-acl-basic-2001] quit

# Configure VLAN-interface 101 as a C-BSR and a C-RP for admin-scoped zone 1.

[SwitchB] pim

[SwitchB-pim] c-bsr 10.110.1.2 scope 239.0.0.0 8

[SwitchB-pim] c-rp 10.110.1.2 group-policy 2001

[SwitchB-pim] quit

# On Switch D, configure the service scope of RP advertisements.

[SwitchD] acl number 2001

[SwitchD-acl-basic-2001] rule permit source 239.0.0.0 0.255.255.255

[SwitchD-acl-basic-2001] quit

# Configure VLAN-interface 105 as a C-BSR and a C-RP for admin-scoped zone 2.

[SwitchD] pim

[SwitchD-pim] c-bsr 10.110.5.2 scope 239.0.0.0 8

[SwitchD-pim] c-rp 10.110.5.2 group-policy 2001

[SwitchD-pim] quit

# On Switch F, configure VLAN-interface 109 as a C-BSR and a C-RP for the global-scoped zone.

<SwitchF> system-view

[SwitchF] pim

[SwitchF-pim] c-bsr 10.110.9.1

[SwitchF-pim] c-rp 10.110.9.1

[SwitchF-pim] quit

Verifying the configuration

# Display BSR information on Switch B.

[SwitchB] display pim bsr-info

Scope: non-scoped

State: Accept Preferred

Bootstrap timer: 00:01:44

Elected BSR address: 10.110.9.1

Priority: 64

Hash mask length: 30

Uptime: 00:01:45

Scope: 239.0.0.0/8

State: Elected

Bootstrap timer: 00:00:06

Elected BSR address: 10.110.1.2

Priority: 64

Hash mask length: 30

Uptime: 00:04:54

Candidate BSR address: 10.110.1.2

Priority: 64

Hash mask length: 30

# Display BSR information on Switch D.

[SwitchD] display pim bsr-info

Scope: non-scoped

State: Accept Preferred

Bootstrap timer: 00:01:44

Elected BSR address: 10.110.9.1

Priority: 64

Hash mask length: 30

Uptime: 00:01:45

Scope: 239.0.0.0/8

State: Elected

Bootstrap timer: 00:01:12

Elected BSR address: 10.110.5.2

Priority: 64

Hash mask length: 30

Uptime: 00:03:48

Candidate BSR address: 10.110.5.2

Priority: 64

Hash mask length: 30

# Display BSR information on Switch F.

[SwitchF] display pim bsr-info

Scope: non-scoped

State: Elected

Bootstrap timer: 00:00:49

Elected BSR address: 10.110.9.1

Priority: 64

Hash mask length: 30

Uptime: 00:11:11

Candidate BSR address: 10.110.9.1

Priority: 64

Hash mask length: 30

# Display RP information on Switch B.

[SwitchB] display pim rp-info

BSR RP information:

Scope: non-scoped

Group/MaskLen: 224.0.0.0/4

RP address Priority HoldTime Uptime Expires

10.110.9.1 192 150 00:03:39 00:01:51

Scope: 239.0.0.0/8

Group/MaskLen: 239.0.0.0/8

RP address Priority HoldTime Uptime Expires

10.110.1.2 (local) 192 150 00:07:44 00:01:51

# Display RP information on Switch D.

[SwitchD] display pim rp-info

BSR RP information:

Scope: non-scoped

Group/MaskLen: 224.0.0.0/4

RP address Priority HoldTime Uptime Expires

10.110.9.1 192 150 00:03:42 00:01:48

Scope: 239.0.0.0/8

Group/MaskLen: 239.0.0.0/8

RP address Priority HoldTime Uptime Expires

10.110.5.2 (local) 192 150 00:06:54 00:02:41

# Display RP information on Switch F.

[SwitchF] display pim rp-info

BSR RP information:

Scope: non-scoped

Group/MaskLen: 224.0.0.0/4

RP address Priority HoldTime Uptime Expires

10.110.9.1 (local) 192 150 00:00:32 00:01:58

PIM-SSM configuration example

Network requirements

As shown in Figure 13:

· The receivers receive VOD information through multicast. The receiver groups of different organizations form stub networks, and one or more receiver hosts exist in each stub network. The entire PIM domain operates in the SSM mode.

· Host A and Host C are multicast receivers in two stub networks.

· The SSM group range is 232.1.1.0/24.

· IGMPv3 runs between Switch A and N1 and between Switch B, Switch C, and N2.

Figure 13 Network diagram

Table 4 Interface and IP address assignment

Device	Interface	IP address	Device	Interface	IP address
Switch A	Vlan-int100	10.110.1.1/24	Switch D	Vlan-int300	10.110.5.1/24
Switch A	Vlan-int101	192.168.1.1/24	Switch D	Vlan-int101	192.168.1.2/24
Switch A	Vlan-int102	192.168.9.1/24	Switch D	Vlan-int105	192.168.4.2/24
Switch B	Vlan-int200	10.110.2.1/24	Switch E	Vlan-int104	192.168.3.2/24
Switch B	Vlan-int103	192.168.2.1/24	Switch E	Vlan-int103	192.168.2.2/24
Switch C	Vlan-int200	10.110.2.2/24	Switch E	Vlan-int102	192.168.9.2/24
Switch C	Vlan-int104	192.168.3.1/24	Switch E	Vlan-int105	192.168.4.1/24

Configuration procedure

1. Assign an IP address and subnet mask to each interface according to Figure 13. (Details not shown.)

2. Configure OSPF on the switches in the PIM-SSM domain to make sure the following conditions are met: (Details not shown.)

¡ The switches are interoperable at the network layer.

¡ The switches can dynamically update their routing information.

3. Enable IP multicast routing, IGMP, and PIM-SM:

# On Switch A, enable IP multicast routing.

<SwitchA> system-view

[SwitchA] multicast routing

[SwitchA-mrib] quit

# Enable IGMPv3 on the receiver-side interface (VLAN-interface 100).

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] igmp enable

[SwitchA-Vlan-interface100] igmp version 3

[SwitchA-Vlan-interface100] quit

# Enable PIM-SM on the other interfaces.

[SwitchA] interface vlan-interface 101

[SwitchA-Vlan-interface101] pim sm

[SwitchA-Vlan-interface101] quit

[SwitchA] interface vlan-interface 102

[SwitchA-Vlan-interface102] pim sm

[SwitchA-Vlan-interface102] quit

# Enable IP multicast routing, IGMP, and PIM-SM on Switch B and Switch C in the same way Switch A is configured. (Details not shown.)

# Enable IP multicast routing and PIM-SM on Switch D and Switch E in the same way Switch A is configured. (Details not shown.)

4. Configure the SSM group range:

# Configure the SSM group range as 232.1.1.0/24 on Switch A.

[SwitchA] acl number 2000

[SwitchA-acl-basic-2000] rule permit source 232.1.1.0 0.0.0.255

[SwitchA-acl-basic-2000] quit

[SwitchA] pim

[SwitchA-pim] ssm-policy 2000

[SwitchA-pim] quit

# Configure the SSM group range on Switch B, Switch C, Switch D and Switch E in the same way Switch A is configured. (Details not shown.)

Verifying the configuration

# Display PIM information on Switch A.

[SwitchA] display pim interface

Interface NbrCnt HelloInt DR-Pri DR-Address

Vlan100 0 30 1 10.110.1.1 (local)

Vlan101 1 30 1 192.168.1.2

Vlan102 1 30 1 192.168.9.2

# Send an IGMPv3 report from Host A to join the multicast source and group (10.110.5.100, 232.1.1.1). (Details not shown.)

# Display PIM routing table information on Switch A.

[SwitchA] display pim routing-table

Total 0 (*, G) entry; 1 (S, G) entry

(10.110.5.100, 232.1.1.1)

Protocol: pim-ssm, Flag:

UpTime: 00:13:25

Upstream interface: Vlan-interface101

Upstream neighbor: 192.168.1.2

RPF prime neighbor: 192.168.1.2

Downstream interface(s) information:

Total number of downstreams: 1

1: Vlan-interface100

Protocol: igmp, UpTime: 00:13:25, Expires: 00:03:25

# Display PIM routing table information on Switch D.

[SwitchD] display pim routing-table

Total 0 (*, G) entry; 1 (S, G) entry

(10.110.5.100, 232.1.1.1)

Protocol: pim-ssm, Flag: LOC

UpTime: 00:12:05

Upstream interface: Vlan-interface300

Upstream neighbor: NULL

RPF prime neighbor: NULL

Downstream interface(s) information:

Total number of downstreams: 1

1: Vlan-interface105

Protocol: pim-ssm, UpTime: 00:12:05, Expires: 00:03:25

The output shows that switches on the SPT path (Switch A and Switch D) have generated the correct (S, G) entries.

Troubleshooting PIM

A multicast distribution tree cannot be built correctly

Symptom

No multicast forwarding entries are established on the routers (including routers directly connected with multicast sources or receivers) in a PIM network. A multicast distribution tree cannot be built correctly.

Solution

To resolve the problem:

1. Use display ip routing-table to verify that a unicast route to the multicast source or the RP is available.

2. Use display pim interface to verify PIM information on each interface, especially on the RPF interface. If PIM is not enabled on the interfaces, use pim dm or pim sm to enable PIM-DM or PIM-SM for the interfaces.

3. Use display pim neighbor to verify that the RPF neighbor is a PIM neighbor.

4. Verify that PIM and IGMP are enabled on the interfaces that directly connect to the multicast sources or the receivers.

5. Use display pim interface verbose to verify that the same PIM mode is enabled on the RPF interface on a router and the connected interface of the router's RPF neighbor.

6. Use display current-configuration to verify that the same PIM mode is enabled on all routers. For PIM-SM, verify that the BSR and C-RPs are correctly configured.

7. If the problem persists, contact H3C Support.

Multicast data is abnormally terminated on an intermediate router

Symptom

An intermediate router can receive multicast data successfully, but the data cannot reach the last-hop router. An interface on the intermediate router receives multicast data but does not create an (S, G) entry in the PIM routing table.

Solution

To resolve the problem:

1. Use display current-configuration to verify the multicast forwarding boundary settings. Use multicast boundary to change the multicast forwarding boundary settings to make the multicast packet able to cross the boundary.

2. Use display current-configuration to verify the multicast source policy. Change the ACL rule defined in the source-policy command so that the source/group address of the multicast data can pass ACL filtering.

3. If the problem persists, contact H3C Support.

An RP cannot join an SPT in PIM-SM

Symptom

An RPT cannot be correctly built, or an RP cannot join the SPT toward the multicast source.

Solution

To resolve the problem:

1. Use display ip routing-table to verify that a unicast route to the RP is available on each router.

2. Use display pim rp-info to verify that the dynamic RP information is consistent on all routers.

3. Use display pim rp-info to verify that the same static RPs are configured on all routers on the network.

4. If the problem persists, contact H3C Support.

An RPT cannot be built or multicast source registration fails in PIM-SM

Symptom

The C-RPs cannot unicast advertisement messages to the BSR. The BSR does not advertise BSMs containing C-RP information and has no unicast route to any C-RP. An RPT cannot be correctly established, or the source-side DR cannot register the multicast source with the RP.

Solution

To resolve the problem:

1. Use display ip routing-table to verify the following information:

¡ The unicast routes to the C-RPs and the BSR are available on each router.

¡ A route is available between each C-RP and the BSR.

2. Use display pim bsr-info to verify that the BSR information exists on each router.

3. Use display pim rp-info to verify that the RP information is correct on each router.

4. Use display pim neighbor to verify that PIM neighboring relationship has been correctly established among the routers.

5. If the problem persists, contact H3C Support.

06-IP Multicast Configuration Guide

PIM-DM overview

PIM-SM overview

DR election

Administrative scoping mechanism

Relationship between admin-scoped zones and the global-scoped zone

PIM-SSM overview

Configuring PIM-DM

Enabling PIM-DM

Enabling the state refresh feature

Configuring state refresh parameters

Configuring PIM-DM graft retry timer

Enabling PIM-SM

Configuring a C-BSR

Configuring multicast source registration

Configuring the switchover to SPT

Enabling PIM-SM

Configuring the SSM group range

Configuration guidelines

Configuration procedure

Configuration task list

Configuring a multicast source policy

Configuring a PIM hello policy

Configuring hello message options globally

Configuring hello message options on an interface

Configuring common PIM timers

Configuring common PIM timers globally

Configuring common PIM timers on an interface

Setting the maximum size of each join or prune message

Enabling BFD for PIM

Configuration guidelines

Configuration procedure

PIM configuration examples

Network requirements

Configuration procedure

Verifying the configuration

Network requirements

Configuration procedure

Verifying the configuration

Network requirements

Configuration procedure

Verifying the configuration

Network requirements

Configuration procedure

Verifying the configuration

A multicast distribution tree cannot be built correctly

Symptom

Solution

Symptom

Solution

Symptom

Solution

Symptom

Solution

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