Contents

Configuring PBR·· 1

About PBR· 1

Packet forwarding process· 1

PBR types· 1

Policy· 1

PBR and Track· 2

Restrictions and guidelines: PBR configuration· 2

PBR tasks at a glance· 2

Configuring a policy· 3

Creating a node· 3

Setting match criteria for a node· 3

Configuring actions for a node· 3

Specifying a policy for PBR· 5

Specifying a policy for local PBR· 5

Specifying a policy for interface PBR· 6

Enabling VXLAN-mode PBR· 7

Display and maintenance commands for PBR· 7

PBR configuration examples· 7

Example: Configuring packet type-based local PBR· 7

Example: Configuring packet type-based interface PBR· 9

Configuring PBR

About PBR

Policy-based routing (PBR) uses user-defined policies to route packets. A policy can specify parameters for packets that match specific criteria such as ACLs or that have specific VXLAN IDs. The parameters include the next hop, output interface, default next hop, and default output interface.

Packet forwarding process

The device forwards received packets using the following process:

1.     The device uses PBR to forward matching packets.

2.     If one of the following events occurs, the device searches for a route (except the default route) in the routing table to forward packets:

¡     The packets do not match the PBR policy.

¡     The PBR-based forwarding fails.

3.     If the forwarding fails, the device uses the default next hop or default output interface defined in PBR to forward packets.

4.     If the forwarding fails, the device uses the default route to forward packets.

PBR types

PBR includes the following types:

·     Local PBR—Guides the forwarding of locally generated packets, such as ICMP packets generated by using the ping command.

·     Interface PBR—Guides the forwarding of packets received on an interface.

Policy

A policy includes match criteria and actions to be taken on the matching packets. A policy can have one or multiple nodes as follows:

·     Each node is identified by a node number. A smaller node number has a higher priority.

·     A node contains if-match and apply clauses. An if-match clause specifies a match criterion, and an apply clause specifies an action.

·     A node has a match mode of permit or deny.

A policy compares packets with nodes in priority order. If a packet matches the criteria on a node, it is processed by the action on the node. If the packet does not match any criteria on the node, it goes to the next node for a match. If the packet does not match the criteria on any node, the device performs a routing table lookup.

Relationship between if-match clauses

On a node, you can specify multiple types of if-match clauses but only one if-match clause for each type.

To match a node, a packet must match all types of the if-match clauses for the node.

Relationship between apply clauses

You can specify multiple apply clauses for a node, but some of them might not be executed. For more information about relationship between apply clauses, see "Configuring actions for a node."

Relationship between the match mode and clauses on the node

Does a packet match all the if-match clauses on the node?	Match mode
	Permit	Deny
Yes.	·     If the node contains apply clauses, PBR executes the apply clauses on the node. If the PBR-based forwarding succeeds, PBR does not compare the packet with the next node. ·     If the node does not contain apply clauses, the device performs a routing table lookup for the packet.	The device performs a routing table lookup for the packet.
No.	PBR compares the packet with the next node.	PBR compares the packet with the next node.

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	NOTE: A node that has no if-match clauses matches any packet.

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PBR and Track

PBR can work with the Track feature to dynamically adapt the availability status of an apply clause to the link status of a tracked object. The tracked object can be a next hop, output interface, default next hop, or default output interface.

·     When the track entry associated with an object changes to Negative, the apply clause is invalid.

·     When the track entry changes to Positive or NotReady, the apply clause is valid.

For more information about Track-PBR collaboration, see High Availability Configuration Guide.

Restrictions and guidelines: PBR configuration

If a packet destined for the local device matches a PBR policy, PBR will execute the apply clauses in the policy, including the clause for forwarding. When you configure a PBR policy, be careful to avoid this situation.

PBR tasks at a glance

To configure PBR, perform the following tasks:

1.     Configuring a policy

a.     Creating a node

b.     Setting match criteria for a node

c.     Configuring actions for a node

2.     Specifying a policy for PBR

Choose the following tasks as needed:

¡     Specifying a policy for local PBR

¡     Specifying a policy for interface PBR

3.     (Optional.) Enabling VXLAN-mode PBR

Enable VXLAN mode for PBR on VTEPs to direct packets to VXLAN tunnels.

Configuring a policy

Creating a node

1.     Enter system view.

system-view

2.     Create a node for a policy, and enter its view.

policy-based-route policy-name [ deny | permit ] node node-number

Setting match criteria for a node

Restrictions and guidelines

On a transport network device, you can configure PBR on the Layer 3 interface to guide the forwarding of packets based on VXLAN IDs. On a VTEP, you can configure PBR on the tunnel interface to guide the forwarding of packets based on VXLAN IDs.

Procedure

1.     Enter system view.

system-view

2.     Enter policy node view.

policy-based-route policy-name [ deny | permit ] node node-number

3.     Set match criteria.

¡     Set an ACL match criterion.

if-match acl { acl-number | name acl-name }

By default, no ACL match criterion is set.

The ACL match criterion cannot match Layer 2 information.

An ACL match criterion does not use the permit or deny action and the time range of the specified ACL to match packets.

¡     Set a VXLAN match criterion.

if-match vxlan-id vxlan-id

By default, no VXLAN match criterion is set.

Configuring actions for a node

About apply clauses

The apply clauses allow you to specify the actions to take on matching packets on a node.

The following apply clauses determine the packet forwarding paths in descending order:

·     apply access-vpn vpn-instance

·     apply next-hop

·     apply output-interface

·     apply default-next-hop

·     apply default-output-interface

PBR supports the apply clauses in Table 1.

Table 1 Apply clauses supported in PBR

Clause	Meaning	Remarks
apply precedence	Sets an IP precedence.	This clause is always executed.
apply access-vpn vpn-instance	Sets VPN instances.	If a packet matches a forwarding entry of a specified VPN instance, it is forwarded in the VPN instance.
apply next-hop and apply output-interface	Sets next hops and sets output interfaces.	If both clauses are configured, only the apply next-hop clause is executed.
apply default-next-hop and apply default-output-interface	Sets default next hops and sets default output interfaces.	If both clauses are configured, only the apply default-next-hop clause is executed. The clauses take effect only in the following cases: ·     No next hops or output interfaces are set or the next hops and output interfaces are invalid. ·     The packet does not match any route in the routing table.
apply fail-action-drop next-hop	Sets the action that drops matching packets when all next hops become invalid.	If no next hops are specified on the policy node, this clause drops all packets that match the policy node. This clause is typically used in scenarios that require strict routing paths.

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Restrictions and guidelines

For outbound PBR, you can specify only one next hop and the next hop must be directly connected.

If you specify a next hop or default next hop, PBR periodically performs a lookup in the FIB table to determine its availability. Temporary service interruption might occur if PBR does not update the route immediately after its availability status changes.

Configuring actions to modify packet fields

1.     Enter system view.

system-view

2.     Enter policy node view.

policy-based-route policy-name [ deny | permit ] node node-number

3.     Set an IP precedence.

apply precedence { type | value }

By default, no IP precedence is specified.

Configuring actions to direct packet forwarding

1.     Enter system view.

system-view

2.     Enter policy node view.

policy-based-route policy-name [ deny | permit ] node node-number

3.     Configure actions.

¡     Set VPN instances.

apply access-vpn vpn-instance vpn-instance-name

By default, no VPN instance is specified.

¡     Set next hops.

apply next-hop [ vpn-instance vpn-instance-name ] { ip-address [ direct ] [ track track-entry-number ] }&<1-2>

By default, no next hop is specified.

On a node, you can specify a maximum of two next hops for backup in one command line or by executing this command multiple times.

¡     Set output interfaces.

apply output-interface { interface-type interface-number [ track track-entry-number ] }

By default, no output interface is specified.

The interface specified in this command must be an MPLS TE tunnel interface, tunnel bundle interface, or null interface.

¡     Set default next hops.

apply default-next-hop [ vpn-instance vpn-instance-name ] { ip-address [ direct ] [ track track-entry-number ] }&<1-2>

By default, no default next hop is specified.

On a node, you can specify a maximum of two default next hops for backup in one command line or by executing this command multiple times.

¡     Set default output interfaces.

apply default-output-interface interface-type interface-number [ track track-entry-number ]

By default, no default output interface is specified.

The interface specified in this command must be an MPLS TE tunnel interface, tunnel bundle interface, or null interface.

¡     Set the action that drops matching packets when all next hops specified on the policy node are invalid.

apply fail-action-drop next-hop

By default, the drop action is not configured. The matching packets are forwarded based on the typical packet forwarding process as described in "Packet forwarding process."

This command does not apply to software-forwarded packets.

Specifying a policy for PBR

Specifying a policy for local PBR

About local PBR

Perform this task to specify a policy for local PBR to guide the forwarding of locally generated packets.

Restrictions and guidelines

You can specify only one policy for local PBR and must make sure the specified policy already exists. Before you apply a new policy, you must first remove the current policy.

Local PBR might affect local services such as ping and Telnet. When you use local PBR, make sure you fully understand its impact on local services of the device.

Procedure

1.     Enter system view.

system-view

2.     Specify a policy for local PBR.

ip local policy-based-route policy-name

By default, local PBR is not enabled.

Specifying a policy for interface PBR

About interface PBR

Perform this task to apply a policy to an interface to guide the forwarding of packets received on the interface.

To apply a policy to multiple VLAN interfaces at the same time, you can use the ip policy-based-route apply command. Using this command simplifies configuration and saves device resources.

Restrictions and guidelines

You can apply only one policy to an interface and must make sure the specified policy already exists. Before you can apply a new interface PBR policy to an interface, you must first remove the current policy from the interface.

You can apply a policy to multiple interfaces.

In a VXLAN IP gateway or EVPN gateway deployment, when you apply a policy to an interface on a border gateway, follow these restrictions and guidelines:

·     If the interface is a Layer 3 Ethernet interface, the policy is also applied to its subinterfaces. For more information about VXLAN IP gateway deployment, see VXLAN Configuration Guide.

·     If the interface is a Layer 3 aggregate interface, the policy is also applied to its subinterfaces. For more information about EVPN gateway deployment, see EVPN Configuration Guide.

Prerequisites

When you use interface PBR in conjunction with VXLAN-mode PBR to guide packets on a site-facing interface to a VXLAN tunnel, enable VXLAN-mode PBR before you apply the PBR policy. For more information about VXLAN-mode PBR, see "Enabling VXLAN-mode PBR."

Apply a policy to an interface

1.     Enter system view.

system-view

2.     Enter interface view.

interface interface-type interface-number

3.     Apply a PBR policy to an interface.

ip policy-based-route policy-name [ share-mode ]

By default, no interface policy is applied to an interface.

Apply a policy to a list of VLAN interfaces

1.     Enter system view.

system-view

2.     Apply a policy to a list of VLAN interfaces:

ip policy-based-route policy-name apply vlan-interface interface-list

By default, no policy is applied to the specified VLAN interfaces.

Use this command only when you want to specify a policy for multiple VLAN interfaces.

Enabling VXLAN-mode PBR

VXLAN-mode PBR enables you to guide packets from a site-facing interface on a VXLAN VTEP to a VXLAN tunnel by using a PBR policy. If VXLAN-mode PBR is not enabled, the PBR policy on a site-facing interface cannot guide packets to a VXLAN tunnel.

To enable VXLAN-mode PBR on the device, set the VXLAN hardware resource mode to normal. In other hardware resource modes, the system cannot perform VXLAN-mode PBR. For more information about VXLAN hardware resource modes, see basic VXLAN features configuration in VXLAN Configuration Guide.

Display and maintenance commands for PBR

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

 

Task	Command
Display PBR policy information.	display ip policy-based-route [ policy policy-name ]
Display the PBR configuration and statistics for a VLAN interface.	display ip policy-based-route apply vlan-interface interface-number [ slot slot-number ]
Display interface PBR configuration and statistics.	display ip policy-based-route interface interface-type interface-number [ slot slot-number ]
Display local PBR configuration and statistics.	display ip policy-based-route local [ slot slot-number ]
Display PBR configuration.	display ip policy-based-route setup
Clear PBR statistics.	reset ip policy-based-route statistics [ policy policy-name ]

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PBR configuration examples

Example: Configuring packet type-based local PBR

Network configuration

As shown in Figure 1, Switch B and Switch C do not have a route to reach each other.

Configure PBR on Switch A to forward all TCP packets to the next hop 1.1.2.2 (Switch B).

Figure 1 Network diagram

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Procedure

	IMPORTANT: By default, interfaces on the device are disabled (in ADM or Administratively Down state). To have an interface operate, you must use the undo shutdown command to enable that interface.

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1.     Configure Switch A:

# Create VLAN 10 and VLAN 20.

<SwitchA> system-view

[SwitchA] vlan 10

[SwitchA-vlan10] quit

[SwitchA] vlan 20

[SwitchA-vlan20] quit

# Configure the IP addresses of VLAN-interface 10 and VLAN-interface 20.

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] ip address 1.1.2.1 24

[SwitchA-Vlan-interface10] quit

[SwitchA] interface vlan-interface 20

[SwitchA-Vlan-interface20] ip address 1.1.3.1 24

[SwitchA-Vlan-interface20] quit

# Configure ACL 3101 to match TCP packets.

[SwitchA] acl advanced 3101

[SwitchA-acl-ipv4-adv-3101] rule permit tcp

[SwitchA-acl-ipv4-adv-3101] quit

# Configure Node 5 for the policy aaa to forward TCP packets to next hop 1.1.2.2.

[SwitchA] policy-based-route aaa permit node 5

[SwitchA-pbr-aaa-5] if-match acl 3101

[SwitchA-pbr-aaa-5] apply next-hop 1.1.2.2

[SwitchA-pbr-aaa-5] quit

# Configure local PBR by applying the policy aaa to Switch A.

[SwitchA] ip local policy-based-route aaa

2.     Configure Switch B:

# Create VLAN 10.

<SwitchB> system-view

[SwitchB] vlan 10

[SwitchB-vlan10] quit

# Configure the IP address of VLAN-interface 10.

[SwitchB] interface vlan-interface 10

[SwitchB-Vlan-interface10] ip address 1.1.2.2 24

3.     Configure Switch C:

# Create VLAN 20.

<SwitchC> system-view

[SwitchC] vlan 20

[SwitchC-vlan20] quit

# Configure the IP address of VLAN-interface 20.

[SwitchC] interface vlan-interface 20

[SwitchC-Vlan-interface20] ip address 1.1.3.2 24

Verifying the configuration

# Telnet to Switch B on Switch A. The operation succeeds. (Details not shown.)

# Telnet to Switch C on Switch A. The operation fails. (Details not shown.)

# Ping Switch C from Switch A. The operation succeeds. (Details not shown.)

Telnet uses TCP, and ping uses ICMP. The results show the following:

·     All TCP packets sent from Switch A are forwarded to the next hop 1.1.2.2.

·     Other packets are forwarded through VLAN-interface 20.

·     The local PBR configuration is effective.

Example: Configuring packet type-based interface PBR

Network configuration

As shown in Figure 2, Switch B and Switch C do not have a route to reach each other.

Configure PBR on Switch A to forward all TCP packets received on VLAN-interface 11 to the next hop 1.1.2.2 (Switch B).

Figure 2 Network diagram

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Procedure

	IMPORTANT: By default, interfaces on the device are disabled (in ADM or Administratively Down state). To have an interface operate, you must use the undo shutdown command to enable that interface.

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1.     Make sure Switch B and Switch C can reach Host A. (Details not shown.)

2.     Configure Switch A:

# Create VLAN 10 and VLAN 20.

<SwitchA> system-view

[SwitchA] vlan 10

[SwitchA-vlan10] quit

[SwitchA] vlan 20

[SwitchA-vlan20] quit

# Configure the IP addresses of VLAN-interface 10 and VLAN-interface 20.

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] ip address 1.1.2.1 24

[SwitchA-Vlan-interface10] quit

[SwitchA] interface vlan-interface 20

[SwitchA-Vlan-interface20] ip address 1.1.3.1 24

[SwitchA-Vlan-interface20] quit

# Configure ACL 3101 to match TCP packets.

[SwitchA] acl advanced 3101

[SwitchA-acl-ipv4-adv-3101] rule permit tcp

[SwitchA-acl-ipv4-adv-3101] quit

# Configure Node 5 for the policy aaa to forward TCP packets to next hop 1.1.2.2.

[SwitchA] policy-based-route aaa permit node 5

[SwitchA-pbr-aaa-5] if-match acl 3101

[SwitchA-pbr-aaa-5] apply next-hop 1.1.2.2

[SwitchA-pbr-aaa-5] quit

# Configure interface PBR by applying the policy aaa to VLAN-interface 11.

[SwitchA] interface vlan-interface 11

[SwitchA-Vlan-interface11] ip address 10.110.0.10 24

[SwitchA-Vlan-interface11] ip policy-based-route aaa

[SwitchA-Vlan-interface11] quit

Verifying the configuration

# On Host A, Telnet to Switch B that is directly connected to Switch A. The operation succeeds. (Details not shown.)

# On Host A, Telnet to Switch C that is directly connected to Switch A. The operation fails. (Details not shown.)

# Ping Switch C from Host A. The operation succeeds. (Details not shown.)

Telnet uses TCP, and ping uses ICMP. The results show the following:

·     All TCP packets arriving on VLAN-interface 11 of Switch A are forwarded to next hop 1.1.2.2.

·     Other packets are forwarded through VLAN-interface 20.

·     The interface PBR configuration is effective.