05-Network Connectivity

HomeSupportConfigure & DeployConfiguration GuidesH3C Access Controllers Configuration Guides(R5447P04)-6W10005-Network Connectivity
29-Policy-based routing configuration
Title Size Download
29-Policy-based routing configuration 106.50 KB

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. 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 but only one if-match clause for each type.

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 PBR-based forwarding succeeds, PBR does not compare the packet with the next node.

¡     If PBR-based forwarding fails and the apply continue clause is not configured, PBR does not compare the packet with the next node.

¡     If PBR-based forwarding fails and the apply continue clause is configured, PBR compares 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.

 

NOTE:

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

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: Hardware compatibility with policy-based routing

Hardware series

Model

Product code

Policy-based routing compatibility

WX1800H series

WX1804H-PWR

EWP-WX1804H-PWR-CN

Yes

WX2500H series

WX2508H-PWR-LTE

WX2510H-PWR

WX2510H-F-PWR

WX2540H

WX2540H-F

WX2560H

EWP-WX2508H-PWR-LTE

EWP-WX2510H-PWR

EWP-WX2510H-F-PWR

EWP-WX2540H

EWP-WX2540H-F

EWP-WX2560H

Yes

MAK series

MAK204

MAK206

EWP-MAK204

EWP-MAK206

Yes

WX3000H series

WX3010H

WX3010H-X-PWR

WX3010H-L-PWR

WX3024H

WX3024H-L-PWR

WX3024H-F

EWP-WX3010H

EWP-WX3010H-X-PWR

EWP-WX3010H-L-PWR

EWP-WX3024H

EWP-WX3024H-L-PWR

EWP-WX3024H-F

No

WX3500H series

WX3508H

WX3508H

WX3510H

WX3510H

WX3520H

WX3520H-F

WX3540H

WX3540H

EWP-WX3508H

EWP-WX3508H-F

EWP-WX3510H

EWP-WX3510H-F

EWP-WX3520H

EWP-WX3520H-F

EWP-WX3540H

EWP-WX3540H-F

Yes

WX5500E series

WX5510E

WX5540E

EWP-WX5510E

EWP-WX5540E

Yes

WX5500H series

WX5540H

WX5560H

WX5580H

EWP-WX5540H

EWP-WX5560H

EWP-WX5580H

Yes

Access controller modules

LSUM1WCME0

EWPXM1WCME0

LSQM1WCMX20

LSUM1WCMX20RT

LSQM1WCMX40

LSUM1WCMX40RT

EWPXM2WCMD0F

EWPXM1MAC0F

LSUM1WCME0

EWPXM1WCME0

LSQM1WCMX20

LSUM1WCMX20RT

LSQM1WCMX40

LSUM1WCMX40RT

EWPXM2WCMD0F

EWPXM1MAC0F

Yes

Hardware series

Model

Product code

Policy-based routing compatibility

WX1800H series

WX1804H-PWR

WX1810H-PWR

WX1820H

WX1840H

EWP-WX1804H-PWR

EWP-WX1810H-PWR

EWP-WX1820H

EWP-WX1840H-GL

Yes

WX3800H series

WX3820H

WX3840H

EWP-WX3820H-GL

EWP-WX3840H-GL

Yes

WX5800H series

WX5860H

EWP-WX5860H-GL

Yes

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 SNMP notifications for PBR

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

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.

Configuring actions for a node

About this task

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

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

·     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 ip-df df-value

Sets the Don't Fragment (DF) bit in the IP header.

This clause is always executed.

apply loadshare { next-hop | output-interface | default-next-hop | default-output-interface }

Enables load sharing among multiple next hops, output interfaces, default next hops, or default output interfaces.

Multiple next hops, output interfaces, default next hops, or default output interfaces operate in either primary/backup or load sharing mode. For example:

·     Primary/backup mode—The first configured output interface is used. When the primary output interface fails, the first configured backup output interface takes over.

·     Load sharing mode—Multiple output interfaces load share traffic on a per-packet basis in turn, according to the configuration order. Multiple next hops load share traffic according to their weights.

By default, the primary/backup mode applies.

For the load sharing mode to take effect, make sure multiple next hops, output interfaces, default next hops, or default output interfaces are set in the policy.

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 continue

Compares packets with the next node upon failure on the current node.

The apply continue clause applies when either of the following conditions exist:

·     None of the following clauses is configured for packet forwarding: apply next-hop, apply output-interface, apply default-next-hop, and apply default-output-interface.

·     A clause listed above is configured, but it has become invalid. Then, a routing table lookup also fails for the matching packet. A clause might become invalid because the specified next hop is unreachable or the specified output interface is down.

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.     Configure actions.

¡     Set an IP precedence.

apply precedence { type | value }

By default, no IP precedence is specified.

¡     Set the DF bit in the IP header.

apply ip-df df-value

By default, the DF bit in the IP header is not set.

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 next hops.

apply next-hop { ip-address [ direct ] [ track track-entry-number ] }&<1-n>

By default, no next hops are specified.

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

If multiple next hops on the same subnet are specified for backup, the device first uses the subnet route for the next hops to forward packets when the primary next hop fails. If the subnet route is not available, the device selects a backup next hop.

¡     Enable load sharing among multiple next hops.

apply loadshare next-hop

By default, the next hops operate in primary/backup mode.

¡     Set output interfaces.

apply output-interface { interface-type interface-number [ track track-entry-number ] }&<1-n>

By default, no output interfaces are specified.

On a node, you can specify a maximum of n output interfaces for backup or load sharing in one command line or by executing this command multiple times.

¡     Enable load sharing among multiple output interfaces.

apply loadshare output-interface

By default, the output interfaces operate in primary/backup mode.

¡     Set default next hops.

apply default-next-hop { ip-address [ direct ] [ track track-entry-number ] }&<1-n>

By default, no default next hops are specified.

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

¡     Enable load sharing among multiple default next hops.

apply loadshare default-next-hop

By default, the default next hops operate in primary/backup mode.

¡     Set default output interfaces.

apply default-output-interface { interface-type interface-number [ track track-entry-number ] }&<1-n>

By default, no default output interfaces are specified.

On a node, you can specify a maximum of n default output interfaces for backup or load sharing in one command line or by executing this command multiple times.

¡     Enable load sharing among multiple default output interfaces.

apply loadshare default-output-interface

By default, the default output interfaces operate in primary/backup mode.

Comparing packets with the next node upon match failure on the current node

1.     Enter system view.

system-view

2.     Enter policy node view.

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

3.     Compare packets with the next node upon match failure on the current node.

apply continue

By default, PBR does not compare packets with the next node upon match failure on the current node.

This command takes effect only when the match mode of the node is permit.

Specifying a policy for PBR

Specifying a policy for local PBR

About this task

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 this task

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

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.

Procedure

1.     Enter system view.

system-view

2.     Enter interface view.

interface interface-type interface-number

3.     Specify a policy for interface PBR.

ip policy-based-route policy-name

By default, no policy is applied to an interface.

Enabling SNMP notifications for PBR

About this task

Perform this task to enable SNMP notifications for PBR. PBR can generate notifications and send them to the SNMP module when the next hop becomes invalid. For the PBR notifications to be sent correctly, you must also configure SNMP on the device. For more information about configuring SNMP, see the network management and monitoring configuration guide for the device.

Procedure

1.     Enter system view.

system-view

2.     Enable SNMP notifications for PBR.

snmp-agent trap enable policy-based-route

By default, SNMP notifications are enabled for PBR.

Display and maintenance commands for PBR

IMPORTANT

IMPORTANT:

The WX1800H series, WX2500H series, MAK series, and WX3000H series access controllers do not support parameters or commands that are available only in IRF mode.

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 interface PBR configuration and statistics.

In standalone mode:

display ip policy-based-route interface interface-type interface-number

In IRF mode:

display ip policy-based-route interface interface-type interface-number [ slot slot-number ]

Display local PBR configuration and statistics.

In standalone mode:

display ip policy-based-route local

In IRF mode:

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 ]

 

  • Cloud & AI
  • InterConnect
  • Intelligent Computing
  • Security
  • SMB Products
  • Intelligent Terminal Products
  • Product Support Services
  • Technical Service Solutions
All Services
  • Resource Center
  • Policy
  • Online Help
All Support
  • Become a Partner
  • Partner Resources
  • Partner Business Management
All Partners
  • Profile
  • News & Events
  • Online Exhibition Center
  • Contact Us
All About Us
新华三官网