RIPng is a distance vector routing protocol. It employs UDP to exchange route information through port 521. RIPng uses a hop count to measure the distance to a destination. The hop count is the metric or cost. The hop count from a router to a directly connected network is 0. The hop count between two directly connected routers is 1. When the hop count is greater than or equal to 16, the destination network or host is unreachable.

By default, the routing update is sent every 30 seconds. If the router receives no routing updates from a neighbor within 180 seconds, the routes learned from the neighbor are considered unreachable. If no routing update is received within another 240 seconds, the router removes these routes from the routing table.

RIPng for IPv6 has the following differences from RIP:

· UDP port number—RIPng uses UDP port 521 to send and receive routing information.

· Multicast address—RIPng uses FF02:9 as the link-local-router multicast address.

· Destination Prefix—128-bit destination address prefix.

· Next hop—128-bit IPv6 address.

· Source address—RIPng uses FE80::/10 as the link-local source address.

RIPng route entries

RIP stores routing entries in a database. Each routing entry contains the following elements:

· Destination address—IPv6 address of a destination host or a network.

· Next hop address—IPv6 address of the next hop.

· Egress interface—Egress interface of the route.

· Metric—Cost from the local router to the destination.

· Route time—Time elapsed since the last update. The time is reset to 0 every time the routing entry is updated.

· Route tag—Used for route control. For more information, see "Configuring routing policies."

RIPng packets

RIPng uses request and response packets to exchange routing information as follows:

1. When RIPng starts or needs to update some routing entries, it sends a multicast request packet to neighbors.

2. When a RIPng neighbor receives the request packet, it sends back a response packet that contains the local routing table. RIPng can also advertise route updates in response packets periodically or advertise a triggered update caused by a route change.

3. After RIPng receives a response, it checks the validity of the response before adding routes to its routing table, such as whether the source IPv6 address is the link-local address and whether the port number is correct. A response packet that fails the check is discarded.

Protocols and standards

· RFC 2080, RIPng for IPv6

· RFC 2081, RIPng Protocol Applicability Statement

RIPng configuration task list

Tasks at a glance
(Required.) Configuring basic RIPng
(Optional.) Configuring RIPng route control · Configuring an additional routing metric · Configuring RIPng route summarization · Advertising a default route · Configuring inbound/outbound route filtering · Configuring a preference for RIPng · Configuring RIPng route redistribution
(Optional.) Tuning and optimizing the RIPng network · Configuring RIPng timers · Configuring split horizon and poison reverse · Configuring zero field check on RIPng packets · Configuring the maximum number of ECMP routes
(Optional.) Configuring RIPng Graceful Restart

Configuring basic RIPng

Before you configure basic RIPng, configure IPv6 addresses for interfaces to ensure IPv6 connectivity between neighboring nodes.

To configure basic RIPng:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Create a RIPng process and enter its view.	ripng [ process-id ] [ vpn-instance vpn-instance-name ]	By default, the RIPng process is not created.
3. Return to system view.	quit	N/A
4. Enter interface view.	interface interface-type interface-number	N/A
5. Enable RIPng on the interface.	ripng process-id enable	By default, RIPng is disabled. If RIPng is not enabled on an interface, the interface does not send or receive any RIPng route.

Configuring RIPng route control

Before you configure RIPng, complete the following tasks:

· Configure IPv6 addresses for interfaces to ensure IPv6 connectivity between neighboring nodes.

· Configure basic RIPng.

Configuring an additional routing metric

An additional routing metric (hop count) can be added to the metric of an inbound or outbound RIPng route.

An outbound additional metric is added to the metric of a sent route, and it does not change the route's metric in the routing table.

An inbound additional metric is added to the metric of a received route before the route is added into the routing table, and the route's metric is changed.

To configure an inbound or outbound additional routing metric:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Specify an inbound additional routing metric.	ripng metricin value	The default setting is 0.
4. Specify an outbound additional routing metric.	ripng metricout value	The default setting is 1.

Configuring RIPng route summarization

Configure route summarization on an interface, so RIPng advertises a summary route based on the longest match.

RIPng route summarization improves network scalability, reduces routing table size, and increases routing table lookup efficiency.

For example, RIPng has two specific routes to be advertised through an interface: 1:11:11::24 with a metric of a 2 and 1:11:12::34 with a metric of 3. Configure route summarization on the interface, so RIPng advertises a single route 11::0/16 with a metric of 2.

To configure RIPng route summarization:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Advertise a summary IPv6 prefix.	ripng summary-address ipv6-address prefix-length	By default, the summary IPv6 prefix is not configured.

Advertising a default route

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Configure RIPng to advertise a default route.	ripng default-route { only \| originate } [ cost cost ]	By default, RIPng does not advertise a default route. This command advertises a default route on the current interface regardless of whether the default route is available in the local IPv6 routing table.

Configuring inbound/outbound route filtering

Perform this task to filter inbound or outbound routes by using an IPv6 prefix list. You can also configure RIPng to filter routes redistributed from other routing protocols and routes from a specified neighbor.

To configure a RIPng route filtering policy:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIPng view.	ripng [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure a filter policy to filter incoming routes.	filter-policy { acl6-number \| prefix-list prefix-list-name } import	By default, RIPng does not filter incoming routing information.
4. Configure a filter policy to filter outgoing routes.	filter-policy { acl6-number \| prefix-list prefix-list-name } export [ protocol [ process-id ] ]	By default, RIPng does not filter outgoing routing information.

Configuring a preference for RIPng

Routing protocols each have a preference. When they find routes to the same destination, the route found by the routing protocol with the highest preference is selected as the optimal route. You can manually set a preference for RIPng. The smaller the value, the higher the preference.

To configure a preference for RIPng:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIPng view.	ripng [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure a preference for RIPng.	preference [ route-policy route-policy-name ] value	The default setting is 100.

Configuring RIPng route redistribution

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIPng view.	ripng [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Redistribute routes from other routing protocols.	import-route protocol [ process-id ] [ allow-ibgp ] [ cost cost \| route-policy route-policy-name ] *	By default, RIPng does not redistribute routes from other routing protocols.
4. (Optional.) Configure a default routing metric for redistributed routes.	default cost cost	The default metric of redistributed routes is 0.

Tuning and optimizing the RIPng network

This section describes how to tune and optimize the performance of the RIPng network as well as applications under special network environments.

Before you tune and optimize the RIPng network, complete the following tasks:

· Configure IPv6 addresses for interfaces to ensure IPv6 connectivity between neighboring nodes.

· Configure basic RIPng.

Configuring RIPng timers

You can adjust RIPng timers to optimize the performance of the RIPng network.

When you adjust RIPng timers, consider the network performance, and perform unified configurations on routers running RIPng to avoid unnecessary network traffic or route oscillation.

To configure RIPng timers:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIPng view.	ripng [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure RIPng timers.	timers { garbage-collect garbage-collect-value \| suppress suppress-value \| timeout timeout-value \| update update-value } *	By default: · The update timer is 30 seconds. · The timeout timer is 180 seconds. · The suppress timer is 120 seconds. · The garbage-collect timer is 120 seconds.

Configuring split horizon and poison reverse

If both split horizon and poison reverse are configured, only the poison reverse function takes effect.

Configuring split horizon

Split horizon disables RIP from sending routes through the interface where the routes were learned to prevent routing loops between neighbors.

H3C recommends enabling split horizon to prevent routing loops in normal cases.

To configure split horizon:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Enable split horizon.	ripng split-horizon	By default, split horizon is enabled.

Configuring poison reverse

The poison reverse function enables a route learned from an interface to be advertised through the interface. However, the metric of the route is set to 16, which means the route is unreachable.

To configure poison reverse:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Enable poison reverse.	ripng poison-reverse	By default, poison reverse is disabled.

Configuring zero field check on RIPng packets

Some fields in the RIPng packet header must be zero. These fields are called "zero fields." You can enable zero field check on incoming RIPng packets. If a zero field of a packet contains a non-zero value, RIPng does not process the packets. If you are certain that all packets are trustworthy, disable the zero field check to save CPU resources.

To configure RIPng zero field check:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIPng view.	ripng [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Enable the zero field check on incoming RIPng packets.	checkzero	By default, this feature is enabled.

Configuring the maximum number of ECMP routes

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIPng view.	ripng [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure the maximum number of ECMP routes.	maximum load-balancing number	By default, the maximum number of ECMP routes is 32.

Configuring RIPng Graceful Restart

Graceful Restart (GR) ensures the continuity of packet forwarding when a routing protocol restarts or an active/standby switchover occurs.

· GR Restarter—Graceful restarting router. It must have GR capability.

· GR Helper—A neighbor of the GR Restarter. It helps the GR Restarter to complete the GR process.

After RIPng restarts on a router, the router must learn RIPng routes again and updates its FIB table, which causes network disconnections and route reconvergence.

With the GR feature, the restarting router (known as the "GR Restarter") can notify the event to its GR capable neighbors. GR capable neighbors (known as "GR Helpers") keep their adjacencies with the router within a configurable GR interval. During this process, the FIB table of the router does not change. After the restart, the router contacts its neighbors to retrieve its FIB.

By default, a RIPng-enabled device acts as the GR Helper. Perform this task on the GR Restarter.

To configure GR on the GR Restarter:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable RIPng and enter RIPng view.	ripng [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Enable the GR capability for RIPng.	graceful-restart	By default, RIP GR is disabled.

Displaying and maintaining RIPng

Execute display commands in any view and reset commands in user view.

Task	Command
Display configuration information of a RIPng process.	display ripng [ process-id ]
Display routes in the RIPng database.	display ripng process-id database
Display the routing information of a specified RIPng process.	display ripng process-id route
Display RIPng interface information.	display ripng process-id interface [ interface-type interface-number ]
Reset a RIPng process.	reset ripng process-id process
Clear statistics of a RIPng process.	reset ripng process-id statistics

RIPng configuration examples

By default, Ethernet, VLAN, and aggregate interfaces are down. To configure such an interface, bring the interface up by executing the undo shutdown command.

Basic RIPng configuration example

Network requirements

As shown in Figure 1, all switches run RIPng. Configure Switch B to filter the route 2::/64 learned from Switch A and to forward only the route 4::/64 to Switch A.

Figure 1 Network diagram

Configuration procedure

1. Configure IPv6 addresses for interfaces. (Details not shown.)

2. Configure basic RIPng:

# Configure Switch A.

<SwitchA> system-view

[SwitchA] ripng 1

[SwitchA-ripng-1] quit

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] ripng 1 enable

[SwitchA-Vlan-interface100] quit

[SwitchA] interface vlan-interface 400

[SwitchA-Vlan-interface400] ripng 1 enable

[SwitchA-Vlan-interface400] quit

# Configure Switch B.

<SwitchA> system-view

[SwitchA] ripng 1

[SwitchA-ripng-1] quit

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] ripng 1 enable

[SwitchA-Vlan-interface100] quit

[SwitchA] interface vlan-interface 400

[SwitchA-Vlan-interface400] ripng 1 enable

[SwitchA-Vlan-interface400] quit

# Configure Switch C.

<SwitchC> system-view

[SwitchC] ripng 1

[SwitchC-ripng-1] quit

[SwitchC] interface vlan-interface 200

[SwitchC-Vlan-interface200] ripng 1 enable

[SwitchC-Vlan-interface200] quit

[SwitchC] interface vlan-interface 500

[SwitchC-Vlan-interface500] ripng 1 enable

[SwitchC-Vlan-interface500] quit

[SwitchC] interface vlan-interface 600

[SwitchC-Vlan-interface600] ripng 1 enable

[SwitchC-Vlan-interface600] quit

# Display the RIPng routing table on Switch B.

[SwitchB] display ripng 1 route

Route Flags: A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::20F:E2FF:FE23:82F5 on Vlan-interface100

Dest 1::/64,

via FE80::20F:E2FF:FE23:82F5, cost 1, tag 0, A, 6 Sec

Dest 2::/64,

via FE80::20F:E2FF:FE23:82F5, cost 1, tag 0, A, 6 Sec

Peer FE80::20F:E2FF:FE00:100 on Vlan-interface200

Dest 3::/64,

via FE80::20F:E2FF:FE00:100, cost 1, tag 0, A, 11 Sec

Dest 4::/64,

via FE80::20F:E2FF:FE00:100, cost 1, tag 0, A, 11 Sec

Dest 5::/64,

via FE80::20F:E2FF:FE00:100, cost 1, tag 0, A, 11 Sec

# Display the RIPng routing table on Switch A.

[SwitchA] display ripng 1 route

Route Flags: A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::200:2FF:FE64:8904 on Vlan-interface100

Dest 1::/64,

via FE80::200:2FF:FE64:8904, cost 1, tag 0, A, 31 Sec

Dest 3::/64,

via FE80::200:2FF:FE64:8904, cost 1, tag 0, A, 31 Sec

Dest 4::/64,

via FE80::200:2FF:FE64:8904, cost 2, tag 0, A, 31 Sec

Dest 5::/64,

via FE80::200:2FF:FE64:8904, cost 2, tag 0, A, 31 Sec

3. Configure route filtering:

# Use IPv6 prefix lists on Switch B to filter inbound and outbound routes.

[SwitchB] ipv6 prefix-list aaa permit 4:: 64

[SwitchB] ipv6 prefix-list bbb deny 2:: 64

[SwitchB] ipv6 prefix-list bbb permit :: 0 less-equal 128

[SwitchB] ripng 1

[SwitchB-ripng-1] filter-policy prefix-list aaa export

[SwitchB-ripng-1] filter-policy prefix-list bbb import

[SwitchB-ripng-1] quit

# Display RIPng routing tables on Switch B and Switch A.

[SwitchB] display ripng 1 route

Route Flags: A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::1:100 on Vlan-interface100

Destination 1::/64,

via FE80::2:100, cost 1, tag 0, A, 6 secs

Peer FE80::3:200 on Vlan-interface200

Destination 3::/64,

via FE80::2:200, cost 1, tag 0, A, 11 secs

Destination 4::/64,

via FE80::2:200, cost 1, tag 0, A, 11 secs

Destination 5::/64,

via FE80::2:200, cost 1, tag 0, A, 11 secs

[SwitchA] display ripng 1 route

Route Flags: A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::2:100 on GigabitEthernet3/0/1

Destination 4::/64,

via FE80::1:100, cost 2, tag 0, A, 2 secs

Configuring RIPng route redistribution

Network requirements

As shown in Figure 2, Switch B communicates with Switch A through RIPng 100 and with Switch C through RIPng 200.

Configure route redistribution on Switch B, so the two RIPng processes can redistribute routes from each other.

Figure 2 Network diagram

Configuration procedure

1. Configure IPv6 addresses for interfaces. (Details not shown.)

2. Configure basic RIPng:

# Enable RIPng 100 on Switch A.

<SwitchA> system-view

[SwitchA] ripng 100

[SwitchA-ripng-100] quit

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] ripng 100 enable

[SwitchA-Vlan-interface100] quit

[SwitchA] interface vlan-interface 200

[SwitchA-Vlan-interface200] ripng 100 enable

[SwitchA-Vlan-interface200] quit

# Enable RIP 100 and RIP 200 on Switch B.

<SwitchB> system-view

[SwitchB] ripng 100

[SwitchB-ripng-100] quit

[SwitchB] interface vlan-interface 100

[SwitchB-Vlan-interface100] ripng 100 enable

[SwitchB-Vlan-interface100] quit

[SwitchB] ripng 200

[SwitchB-ripng-200] quit

[SwitchB] interface vlan-interface 300

[SwitchB-Vlan-interface300] ripng 200 enable

[SwitchB-Vlan-interface300] quit

# Enable RIPng 200 on Switch C.

<SwitchC> system-view

[SwitchC] ripng 200

[SwitchC] interface vlan-interface 300

[SwitchC-Vlan-interface300] ripng 200 enable

[SwitchC-Vlan-interface300] quit

[SwitchC] interface vlan-interface 400

[SwitchC-Vlan-interface400] ripng 200 enable

[SwitchC-Vlan-interface400] quit

# Display the routing table on Switch A.

[SwitchA] display ipv6 routing-table

Destinations : 7 Routes : 7

Destination: ::1/128 Protocol : Direct

NextHop : ::1 Preference: 0

Interface : InLoop0 Cost : 0

Destination: 1::/64 Protocol : Direct

NextHop : 1::1 Preference: 0

Interface : Vlan100 Cost : 0

Destination: 1::1/128 Protocol : Direct

NextHop : ::1 Preference: 0

Interface : InLoop0 Cost : 0

Destination: 2::/64 Protocol : Direct

NextHop : 2::1 Preference: 0

Interface : Vlan200 Cost : 0

Destination: 2::1/128 Protocol : Direct

NextHop : ::1 Preference: 0

Interface : InLoop0 Cost : 0

Destination: FE80::/10 Protocol : Direct

NextHop : :: Preference: 0

Interface : NULL0 Cost : 0

Destination: FF00::/8 Protocol : Direct

NextHop : :: Preference: 0

Interface : NULL0 Cost : 0

3. Configure RIPng route redistribution:

# Configure route redistribution between the two RIPng processes on Switch B.

[SwitchB] ripng 100

[SwitchB-ripng-100] import-route ripng 200

[SwitchB-ripng-100] quit

[SwitchB] ripng 200

[SwitchB-ripng-200] import-route ripng 100

[SwitchB-ripng-200] quit

# Display the routing table on Switch A.

[SwitchA] display ipv6 routing-table

Destinations : 8 Routes : 8

Destination: ::1/128 Protocol : Direct

NextHop : ::1 Preference: 0

Interface : InLoop0 Cost : 0

Destination: 1::/64 Protocol : Direct

NextHop : 1::1 Preference: 0

Interface : Vlan100 Cost : 0

Destination: 1::1/128 Protocol : Direct

NextHop : ::1 Preference: 0

Interface : InLoop0 Cost : 0

Destination: 2::/64 Protocol : Direct

NextHop : 2::1 Preference: 0

Interface : Vlan200 Cost : 0

Destination: 2::1/128 Protocol : Direct

NextHop : ::1 Preference: 0

Interface : InLoop0 Cost : 0

Destination: 4::/64 Protocol : RIPng

NextHop : FE80::200:BFF:FE01:1C02 Preference: 100

Interface : Vlan100 Cost : 1

Destination: FE80::/10 Protocol : Direct

NextHop : :: Preference: 0

Interface : NULL0 Cost : 0d

Destination: FF00::/8 Protocol : Direct

NextHop : :: Preference: 0

Interface : NULL0 Cost : 0

06-Layer 3 - IP Routing Configuration Guide

Overview

RIPng route entries

RIPng packets

RIPng configuration task list

Configuring RIPng route control

Configuring a preference for RIPng

Configuring RIPng route redistribution

Tuning and optimizing the RIPng network

Configuring split horizon and poison reverse

Configuring split horizon

Configuring poison reverse

Configuring zero field check on RIPng packets

Configuring the maximum number of ECMP routes

RIPng configuration examples

Network requirements

Configuration procedure

Network requirements

Configuration procedure

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