Contents

Configuring routing policies· 1

Overview·· 1

Filters· 1

Routing policy· 1

Configuring filters· 2

Configuration prerequisites· 2

Configuring an IP prefix list 2

Configuring an AS path list 3

Configuring a community list 3

Configuring an extended community list 3

Configuring a routing policy· 4

Configuration prerequisites· 4

Creating a routing policy· 4

Configuring if-match clauses· 4

Configuring apply clauses· 5

Configuring a continue clause· 7

Displaying and maintaining the routing policy· 7

Routing policy configuration examples· 8

Routing policy configuration example for IPv4 route redistribution· 8

Routing policy configuration example for IPv6 route redistribution· 10

Configuring routing policies

Overview

Routing policies can filter advertised, received, and redistributed routes, and modify attributes for specific routes.

To configure a routing policy:

1.        Configure filters based on route attributes, such as destination address and the advertising router's address.

2.        Create a routing policy and apply filters to the routing policy.

Filters

Routing policies can use the following filters to match routes.

ACL

An ACL can match the destination or next hop of routing information.

For more information about ACLs, see ACL and QoS Configuration Guide.

IP prefix list

An IP prefix list matches the destination address of routing information. You can use the gateway option to receive routing information only from specific routers. For more information about the gateway option, see "Configuring RIP" and "Configuring OSPF."

An IP prefix list, identified by name, can comprise multiple items. Each item, identified by an index number, specifies a prefix range to match. An item with a smaller index number is matched first. A route that matches one item matches the IP prefix list.

AS path list

An AS path list matches the AS_PATH attribute of BGP routing information.

For more information about AS path lists, see "Configuring BGP."

Community list

A community list matches the COMMUNITY attribute of BGP routing information.

For more information about community lists, see "Configuring BGP."

Extended community list

An extended community list matches the extended community attribute of BGP routing information.

Routing policy

A routing policy can comprise multiple nodes, which are in a logical OR relationship. A node with a smaller number is matched first. A route (except the route configured with the continue clauses) that matches one node matches the routing policy.

Each node has a match mode of permit or deny.

·          permit—Specifies the permit match mode for a routing policy node. If a route matches all the if-match clauses of the node, it is handled by the apply clauses of the node and does not match against the next node unless the continue clause is configured. If not, it matches against the next node.

·          deny—Specifies the deny match mode for a routing policy node. The apply and continue clauses of a deny-mode node are never executed. If a route matches all the if-match clauses of the node, it is discarded and does not match against the next node. If a route does not match all the if-match clauses of the node, it matches against the next node.

A node can comprise a set of if-match, apply, and continue clauses.

·          if-match clauses—Configure the match criteria that match the attributes of routing information. The if-match clauses are in a logical AND relationship. A route must match all the if-match clauses to match the node.

·          apply clauses—Specify the actions to be taken on permitted routes, such as modifying a route attribute.

·          continue clause—Specify the next node. A route that matches the current node (permit-mode node) must match the specified next node in the same routing policy. The continue clause combines the if-match and apply clauses of the two nodes to improve flexibility of the routing policy.

Follow these guidelines when you configure if-match, apply, and continue clauses:

·          If you only want to filter routes, do not configure apply clauses.

·          If you do not configure any if-match clauses for a permit-mode node, the node will permit all routes.

·          Configure a permit-mode node containing no if-match or apply clauses behind multiple deny-mode nodes to allow unmatched routes to pass.

Configuring filters

Configuration prerequisites

Determine the IP prefix list name, matching address range, and community list number.

Configuring an IP prefix list

Configuring an IPv4 prefix list

If all the items are set to deny mode, no routes can pass the IP prefix list. To permit unmatched IPv4 routes, you must configure the permit 0.0.0.0 0 less-equal 32 item following multiple deny items.

To configure an IPv4 prefix list:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Configure an IPv4 prefix list.	ip prefix-list prefix-list-name [ index index-number ] { deny | permit } ip-address mask-length [ greater-equal min-mask-length ] [ less-equal max-mask-length ]	By default, no IPv4 prefix lists exist.

 

Configuring an IPv6 prefix list

If all items are set to deny mode, no routes can pass the IPv6 prefix list. To permit unmatched IPv6 routes, you must configure the permit :: 0 less-equal 128 item following multiple deny items.

To configure an IPv6 prefix list:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Configure an IPv6 prefix list.	ipv6 prefix-list prefix-list-name [ index index-number ] { deny | permit } ipv6-address { prefix-length | inverse inverse-prefix-length [ greater-equal min-prefix-length ] [ less-equal max-prefix-length ] }	By default, no IPv6 prefix lists exist.

 

Configuring an AS path list

You can configure multiple items for an AS path list that is identified by a number. The relationship between items is logical OR. A route that matches one item matches the AS path list.

To configure an AS path list:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Configure an AS path list.	ip as-path as-path-number { deny | permit } regular-expression	By default, no AS path list is configured.

 

Configuring a community list

You can configure multiple items for a community list that is identified by number. The relationship between the items is logic OR. A route that matches one item matches the community list.

To configure a community list:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Configure a community list.	·         Configure a basic community list: ip community-list { basic-comm-list-num | basic basic-comm-list-name } { deny | permit } [ community-number&<1-32> | aa:nn&<1-32> ] [ internet | no-advertise | no-export | no-export-subconfed ] * ·         Configure an advanced community list: ip community-list { adv-comm-list-num | advanced adv-comm-list-name } { deny | permit } regular-expression	Use either method. By default, no community list is configured.

 

Configuring an extended community list

You can configure multiple items for an extended community list that is identified by a number. The relationship between items is logic OR. A route that matches one item matches the extended community list.

To configure an extended community list:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Configure an extended community list.	ip extcommunity-list ext-comm-list-number { deny | permit } { rt route-target }&<1-32>	By default, no extended community list is configured.

 

Configuring a routing policy

Configuration prerequisites

Configure filters and routing protocols, and determine the routing policy name, node numbers, match criteria, and the attributes to be modified.

Creating a routing policy

For a routing policy that has more than one node, configure at least one permit-mode node. A route that does not match any node cannot pass the routing policy. If all the nodes are in deny mode, no routing information can pass the routing policy.

To create a routing policy:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Create a routing policy and a node, and enter routing policy node view.	route-policy route-policy-name { deny | permit } node node-number	By default, no routing policy is created.

 

Configuring if-match clauses

You can either specify no if-match clauses or multiple if-match clauses for a routing policy node. If no if-match clause is specified for a permit-mode node, all routing information can pass the node. If no if-match clause is specified for a deny-mode node, no routing information can pass the node.

The if-match clauses of a routing policy node have a logical AND relationship. A route must meet all if-match clauses before it can be executed by the apply clauses of the node. If an if-match command exceeds the maximum length, multiple identical if-match clauses are generated. These clauses have a logical OR relationship. A route only needs to match one of them.

To configure if-match clauses:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Enter routing policy node view.	route-policy route-policy-name { deny | permit } node node-number	N/A
3.       Match routes whose destination, next hop, or source address matches an ACL or prefix list.	·         Match IPv4 routes whose destination, next hop, or source address matches an ACL or IPv4 prefix list: if-match ip { address | next-hop | route-source } { acl acl-number | prefix-list prefix-list-name } ·         Match IPv6 routes whose destination, next hop, or source address matches an ACL or IPv6 prefix list: if-match ipv6 { address | next-hop | route-source } { acl ipv6-acl-number | prefix-list prefix-list-name }	By default, no prefix list match criterion is configured. If the ACL used by an if-match clause does not exist, the clause is always matched. If no rules of the specified ACL are matched or the match rules are inactive, the clause is not matched. All IPv6 routes match a node if the if-match clauses of the node use only IPv4 ACLs. All IPv4 routes match a node if the if-match clauses of the node use only IPv6 ACLs.
4.       Match BGP routes whose AS_PATH attribute matches a specified AS path list.	if-match as-path as-path-number&<1-32>	By default, no AS path match criterion is configured.
5.       Match BGP routes whose COMMUNITY attribute matches a specified community list.	if-match community { { basic-community-list-number | name comm-list-name } [ whole-match ] | adv-community-list-number }&<1-32>	By default, no COMMUNITY match criterion is matched.
6.       Match routes having the specified cost.	if-match cost value	By default, no cost match criterion is configured.
7.       Match BGP routes whose extended community attribute matches a specified extended community list.	if-match extcommunity ext-comm-list-number&<1-32>	By default, no extended community list match criterion is configured.
8.       Match routes having the specified output interface.	if-match interface { interface-type interface-number }&<1-16>	By default, no output interface match criterion is configured. This command is not supported by BGP.
9.       Match BGP routes having the specified local preference.	if-match local-preference preference	By default, no local preference is configured for BGP routes.
10.     Match routes having the specified route type.	if-match route-type { external-type1 | external-type1or2 | external-type2 | internal | is-is-level-1 | is-is-level-2 | nssa-external-type1 | nssa-external-type1or2 | nssa-external-type2 } *	By default, no route type match criterion is configured.
11.     Match RIP, OSPF, and IS-IS routes having the specified tag value.	if-match tag value	By default, no tag match criterion is configured.

 

Configuring apply clauses

To configure apply clauses:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Enter routing policy node view.	route-policy route-policy-name { deny | permit } node node-number	N/A
3.       Set the AS_PATH attribute for BGP routes.	apply as-path as-number&<1-32> [ replace ]	By default, no AS_PATH attribute is set for BGP routes.
4.       Delete the specified COMMUNITY attribute for BGP routes.	apply comm-list { comm-list-number | comm-list-name } delete	By default, no COMMUNITY attribute is deleted for BGP routes.
5.       Set the specified COMMUNITY attribute for BGP routes.	apply community { none | additive | { community-number&<1-32> | aa:nn&<1-32> | internet | no-advertise | no-export | no-export-subconfed } * [ additive ] }	By default, no community attribute is set for BGP routes.
6.       Set a cost for routes.	apply cost [ + | - ] value	By default, no cost is set for routes.
7.       Set a cost type for routes.	apply cost-type { external | internal | type-1 | type-2 }	By default, no cost type is set for routes.
8.       Set the extended community attribute for BGP routes.	apply extcommunity { rt route-target }&<1-32> [ additive ]	By default, no extended community attribute is set for BGP routes.
9.       Set the next hop for routes.	·         Set the next hop for IPv4 routes: apply ip-address next-hop ip-address [ public | vpn-instance vpn-instance-name ] ·         Set the next hop for IPv6 routes: apply ipv6 next-hop ipv6-address	By default, no next hop is set for IPv4 or IPv6 routes. The apply ip-address next-hop and apply ipv6 next-hop commands do not apply to redistributed routes.
10.     Redistribute routes to a specified ISIS level.	apply isis { level-1 | level-1-2 | level-2 }	By default, routes are not redistributed into a specified IS-IS level.
11.     Set a local preference for BGP routes.	apply local-preference preference	By default, no local preference is set for BGP routes.
12.     Set the ORIGIN attribute for BGP routes.	apply origin { egp as-number | igp | incomplete }	By default, no ORIGIN attribute is set for BGP routes.
13.     Set a preference.	apply preference preference	By default, no preference is set.
14.     Set a preferred value for BGP routes.	apply preferred-value preferred-value	By default, no preferred value is set for BGP routes.
15.     Set a prefix priority.	apply prefix-priority { critical | high | medium }	By default, no prefix priority is set, which means the prefix priority is low.
16.     Set a tag value for RIP, OSPF, and IS-IS route.	apply tag value	By default, no tag value is set for RIP, OSPF, and IS-IS routes.
17.     Set a backup link for fast reroute (FRR).	·         Set an IPv4 backup link for FRR: apply fast-reroute { backup-interface interface-type interface-number [ backup-nexthop ip-address ] | backup-nexthop ip-address } ·         Set an IPv6 backup link for FRR: apply ipv6 fast-reroute backup-nexthop ipv6-address	By default, no backup link is set for FRR.

 

Configuring a continue clause

Follow these guidelines when you configure a continue clause:

·          If you configure the same type of apply clauses that set different values on nodes that are combined by the continue clause, and the apply clauses are not configured with the additive keyword, the apply clause configured on the last matching node takes effect. If the apply clauses are configured with the additive keyword (including the apply as-path clauses without the replace keyword, the apply cost clauses with the + or - keyword, the apply community clauses with the additive keyword, and the apply extcommunity clauses with the additive keyword), all the apply clauses configured on the matching nodes take effect.

·          If you configure the apply community clause for multiple nodes that are combined by the continue clause, the apply comm-list delete clause configured on the current node cannot delete the community attributes set by preceding nodes.

To configure a continue clause:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Enter routing policy node view.	route-policy route-policy-name { deny | permit } node node-number	N/A
3.       Specify the next node to be matched.	continue [ node-number ]	By default, no continue clause is configured. The specified next node must have a larger number than the current node.

 

Displaying and maintaining the routing policy

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

 

Task	Command
Display BGP AS path list information.	display ip as-path [ as-path-number ]
Display BGP community list information.	display ip community-list [ basic-community-list-number | adv-community-list-number | name comm-list-name ]
Display BGP extended community list information.	display ip extcommunity-list [ ext-comm-list-number ]
Display IPv4 prefix list statistics.	display ip prefix-list [ name prefix-list-name ]
Display IPv6 prefix list statistics.	display ipv6 prefix-list [ name prefix-list-name ]
Display routing policy information.	display route-policy [ name route-policy-name ]
Clear IPv4 prefix list statistics.	reset ip prefix-list [ prefix-list-name ]
Clear IPv6 prefix list statistics.	reset ipv6 prefix-list [ prefix-list-name ]

 

Routing policy configuration examples

Routing policy configuration example for IPv4 route redistribution

Network Requirements

As shown in Figure 1, Switch B exchanges routing information with Switch A by using OSPF and with Switch C by using IS-IS.

On Switch B, enable route redistribution from IS-IS to OSPF, and use a routing policy to set the cost of route 172.17.1.0/24 to 100 and the tag of route 172.17.2.0/24 to 20.

Figure 1 Network diagram

 

Configuration procedure

1.        Specify IP addresses for interfaces. (Details not shown.)

2.        Configure IS-IS:

# Configure Switch C.

<SwitchC> system-view

[SwitchC] isis

[SwitchC-isis-1] is-level level-2

[SwitchC-isis-1] network-entity 10.0000.0000.0001.00

[SwitchC-isis-1] quit

[SwitchC] interface vlan-interface 200

[SwitchC-Vlan-interface200] isis enable

[SwitchC-Vlan-interface200] quit

[SwitchC] interface vlan-interface 201

[SwitchC-Vlan-interface201] isis enable

[SwitchC-Vlan-interface201] quit

[SwitchC] interface vlan-interface 202

[SwitchC-Vlan-interface202] isis enable

[SwitchC-Vlan-interface202] quit

[SwitchC] interface vlan-interface 203

[SwitchC-Vlan-interface203] isis enable

[SwitchC-Vlan-interface203] quit

# Configure Switch B.

<SwitchB> system-view

[SwitchB] isis

[SwitchB-isis-1] is-level level-2

[SwitchB-isis-1] network-entity 10.0000.0000.0002.00

[SwitchB-isis-1] quit

[SwitchB] interface vlan-interface 200

[SwitchB-Vlan-interface200] isis enable

[SwitchB-Vlan-interface200] quit

3.        Configure OSPF and route redistribution:

# Configure OSPF on Switch A.

<SwitchA> system-view

[SwitchA] ospf

[SwitchA-ospf-1] area 0

[SwitchA-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255

[SwitchA-ospf-1-area-0.0.0.0] quit

[SwitchA-ospf-1] quit

# On Switch B, configure OSPF and enable route redistribution from IS-IS.

[SwitchB] ospf

[SwitchB-ospf-1] area 0

[SwitchB-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255

[SwitchB-ospf-1-area-0.0.0.0] quit

[SwitchB-ospf-1] import-route isis 1

[SwitchB-ospf-1] quit

# Display the OSPF routing table on Switch A to view redistributed routes.

[SwitchA] display ospf routing

 

          OSPF Process 1 with Router ID 192.168.1.1

                   Routing Tables

 

 Routing for Network

 Destination        Cost     Type    NextHop        AdvRouter     Area

 192.168.1.0/24     1        Stub    192.168.1.1    192.168.1.1   0.0.0.0

 

 Routing for ASEs

 Destination        Cost     Type    Tag        NextHop        AdvRouter

 172.17.1.0/24      1        Type2   1          192.168.1.2    192.168.2.2

 172.17.2.0/24      1        Type2   1          192.168.1.2    192.168.2.2

 172.17.3.0/24      1        Type2   1          192.168.1.2    192.168.2.2

 

 Total Nets: 4

 Intra Area: 1  Inter Area: 0  ASE: 3  NSSA: 0

4.        Configure filtering lists:

# Configure ACL 2002 to permit route 172.17.2.0/24.

[SwitchB] acl number 2002

[SwitchB-acl-basic-2002] rule permit source 172.17.2.0 0.0.0.255

[SwitchB-acl-basic-2002] quit

# Configure IP prefix list prefix-a to permit route 172.17.1.0/24.

[SwitchB] ip prefix-list prefix-a index 10 permit 172.17.1.0 24

5.        Configure a routing policy.

[SwitchB] route-policy isis2ospf permit node 10

[SwitchB-route-policy-isis2ospf-10] if-match ip address prefix-list prefix-a

[SwitchB-route-policy-isis2ospf-10] apply cost 100

[SwitchB-route-policy-isis2ospf-10] quit

[SwitchB] route-policy isis2ospf permit node 20

[SwitchB-route-policy-isis2ospf-20] if-match ip address acl 2002

[SwitchB-route-policy-isis2ospf-20] apply tag 20

[SwitchB-route-policy-isis2ospf-20] quit

[SwitchB] route-policy isis2ospf permit node 30

[SwitchB-route-policy-isis2ospf-30] quit

6.        Apply the routing policy to route redistribution:

# On Switch B, enable route redistribution from IS-IS and apply the routing policy.

[SwitchB] ospf

[SwitchB-ospf-1] import-route isis 1 route-policy isis2ospf

[SwitchB-ospf-1] quit

# Display the OSPF routing table on Switch A.

[SwitchA] display ospf routing

 

          OSPF Process 1 with Router ID 192.168.1.1

                   Routing Tables

 

 Routing for Network

 Destination        Cost     Type    NextHop         AdvRouter     Area

 192.168.1.0/24     1        Transit 192.168.1.1     192.168.1.1   0.0.0.0

 

 Routing for ASEs

 Destination        Cost     Type    Tag         NextHop       AdvRouter

 172.17.1.0/24      100      Type2   1           192.168.1.2   192.168.2.2

 172.17.2.0/24      1        Type2   20          192.168.1.2   192.168.2.2

 172.17.3.0/24      1        Type2   1           192.168.1.2   192.168.2.2

 

 Total Nets: 4

 Intra Area: 1  Inter Area: 0  ASE: 3  NSSA: 0

The output shows that the cost of route 172.17.1.0/24 is 100 and the tag of route 172.17.2.0/24 is 20.

Routing policy configuration example for IPv6 route redistribution

Network requirements

As shown in Figure 2:

·          Run RIPng on Switch A and Switch B.

·          Configure three static routes on Switch A.

·          On Switch A, apply a routing policy to redistribute static routes 20::/32 and 40::/32 and deny route 30::/32.

Figure 2 Network diagram

 

Configuration procedure

1.        Configure Switch A:

# Configure IPv6 addresses for VLAN-interface 100 and VLAN-interface 200.

<SwitchA> system-view

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] ipv6 address 10::1 32

[SwitchA-Vlan-interface100] quit

[SwitchA] interface vlan-interface 200

[SwitchA-Vlan-interface200] ipv6 address 11::1 32

[SwitchA-Vlan-interface200] quit

# Enable RIPng on VLAN-interface 100.

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] ripng 1 enable

[SwitchA-Vlan-interface100] quit

# Configure three static routes with next hop 11::2, and make sure the static routes are active.

[SwitchA] ipv6 route-static 20:: 32 11::2

[SwitchA] ipv6 route-static 30:: 32 11::2

[SwitchA] ipv6 route-static 40:: 32 11::2

# Configure a routing policy.

[SwitchA] ipv6 prefix-list a index 10 permit 30:: 32

[SwitchA] route-policy static2ripng deny node 0

[SwitchA-route-policy-static2ripng-0] if-match ipv6 address prefix-list a

[SwitchA-route-policy-static2ripng-0] quit

[SwitchA] route-policy static2ripng permit node 10

[SwitchA-route-policy-static2ripng-10] quit

# Enable RIPng and apply the routing policy to static route redistribution.

[SwitchA] ripng

[SwitchA-ripng-1] import-route static route-policy static2ripng

2.        Configure Switch B:

# Configure the IPv6 address for VLAN-interface 100.

<SwitchB> system-view

[SwitchB] interface vlan-interface 100

[SwitchB-Vlan-interface100] ipv6 address 10::2 32

# Enable RIPng.

[SwitchB] ripng

[SwitchB-ripng-1] quit

# Enable RIPng on VLAN-interface 100.

[SwitchB] interface vlan-interface 100

[SwitchB-Vlan-interface100] ripng 1 enable

[SwitchB-Vlan-interface100] quit

Verifying the configuration

# Display the RIPng routing table on Switch B.

[SwitchB] display ripng 1 route

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

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

 

 Peer FE80::7D58:0:CA03:1 on Vlan-interface 100

 Destination 10::/32,

     via FE80::7D58:0:CA03:1, cost 1, tag 0, A, 18 secs

 Destination 20::/32,

     via FE80::7D58:0:CA03:1, cost 1, tag 0, A, 8 secs

 Destination 40::/32,

     via FE80::7D58:0:CA03:1, cost 1, tag 0, A, 3 secs