Contents

1   Overview

This document provides an overview of routing policies and describes the tasks and commands used to configure, monitor, troubleshoot, and administer routing policy features through the SmartEdge® router.

Routing policies allow you to enforce routing policy decisions onto incoming, outgoing, and redistributed routes. The tools to configure routing policies include Border Gateway Protocol (BGP) autonomous system (AS) path lists, BGP community lists, BGP extended community lists, IP prefix lists, IP Version 6 (IPv6) prefix lists, and route maps with match and set conditions.

Note:  

When IPv6 addresses are not referenced or explicitly specified, the term, IP address, can refer generally to IP Version 4 (IPv4) addresses, IPv6 addresses, or IP addressing. In instances where IPv6 addresses are referenced or explicitly specified, the term, IP address, refers only to IPv4 addresses.

2   Configuration and Operations Tasks

Note:  

In this section, the command syntax in the task tables displays only the root command.

To configure routing policies, perform the tasks described in the following sections.

2.1   Configuring AS Path Lists

To configure BGP AS path lists, perform the tasks described in the sections that follow.

2.1.1   Create an AS Path List

To create an AS path list, perform the tasks described in Table 1.

2.1.2   Configure an AS Path List Permit or Deny Condition

When you create several permit or deny conditions for a single list, the system can automatically sequence the entries for you, or you can manually assign a number for each entry. A BGP AS path attribute is compared with BGP AS path list entries in order of ascending sequence number to determine if routes associated with the AS path attribute are permitted or denied.

When you allow the system to automatically sequence entries for you, the system increments each statement by a count of 10. The first statement you enter is assigned the sequence number of 10, the second is assigned the number 20, and so on. This allows room to assign intermediate sequence numbers to statements that you might want to add later. You can also resequence numbers to existing entries in an AS path list.

To configure an AS path list permit or deny condition, perform the tasks described in Table 2. Enter all commands in AS path list configuration mode, unless otherwise noted.

2.2   Configuring BGP Community Lists

To configure BGP community lists, perform the tasks described in the following sections.

2.2.1   Create a BGP Community List

To create a BGP community list, perform the tasks described in Table 3.

2.2.2   Configure a BGP Community List Permit or Deny Condition

When you create several permit or deny conditions for a single BGP community list, the system can automatically sequence the entries for you, or you can manually assign a number for each entry. A BGP community attribute is compared with BGP community list entries in order of ascending sequence number to determine if they are permitted or denied.

When you allow the system to automatically sequence entries, the system increments each statement by a count of 10. The first statement you enter is assigned the sequence number of 10, the second is assigned the number 20, and so on. This allows room to assign intermediate sequence numbers to statements that you might want to add later. You can also resequence existing entries in a BGP community list.

To configure a BGP community list permit or deny condition, perform the tasks described in Table 4. Enter all commands in community list configuration mode, unless otherwise noted.

2.3   Configuring BGP Extended Community Lists

A BGP extended community is a group of destinations that share some common attributes. Extended community attributes are carried in BGP messages as attributes of the route. They identify the route as belonging to a specific collection of routes, all of which are treated the same with respect to routing policy. Each BGP extended community must be globally unique (contains either a public IP address or autonomous system number [ASN]).

BGP/Multiprotocol Label Switching Virtual Private Networks (BGP/MPLS VPNs) use BGP extended community attributes instead of conventional BGP community attributes.

To configure BGP extended community lists, perform the tasks described in the following sections.

2.3.1   Create a BGP Extended Community List

To create a BGP extended community list, perform the tasks described in Table 5.

2.3.2   Configure a BGP Extended Community List Permit or Deny Condition

When you create several permit or deny conditions for a single BGP extended community list, the system can automatically sequence the entries for you, or you can manually assign a number for each entry. A BGP extended community attribute is compared with BGP extended community list entries in order of ascending sequence number to determine if they are permitted or denied.

When you allow the system to automatically sequence entries for you, the system increments each statement by a count of 10. The first statement you enter is assigned the sequence number of 10, the second is assigned the number 20, and so on. This allows room to assign intermediate sequence numbers to statements that you might want to add later. You can also resequence existing entries in a BGP extended community list.

To configure a BGP extended community list permit or deny condition, perform the tasks described in Table 6. Enter all commands in extended community list configuration mode, unless otherwise noted.

2.4   Configuring IP Prefix Lists

To configure IP prefix lists, perform the tasks described in the following sections.

2.4.1   Create an IP Prefix List

To create an IP prefix list, perform the tasks described in Table 7.

2.4.2   Configure an IP Prefix List Permit or Deny Condition

When you create several permit or deny conditions for a single IP prefix list, the system can automatically sequence the entries for you, or you can manually assign a number for each entry.

When you allow the system to automatically sequence the entries for you, the system increments each statement by a count of 10. The first statement you enter is assigned the sequence number of 10, the second is assigned the number 20, and so on. This allows room to assign intermediate sequence numbers to statements that you might want to add later. You can also resequence existing entries in an IP prefix list.

To configure an IP prefix list permit or deny condition, perform the tasks described in Table 8. Enter all commands in IP prefix list configuration mode, unless otherwise noted.

2.5   Configuring IPv6 Prefix Lists

To configure IPv6 prefix lists, perform the tasks described in the following sections.

2.5.1   Create an IPv6 Prefix List

To create an IPv6 prefix list, perform the tasks described in Table 9.

2.5.2   Configure an IPv6 Prefix List Permit or Deny Condition

When you create several permit or deny conditions for a single IPv6 prefix list, the system can automatically sequence the entries for you, or you can manually assign a number for each entry.

When you allow the system to automatically sequence the entries for you, the system increments each statement by a count of 10. The first statement you enter is assigned the sequence number of 10, the second is assigned the number 20, and so on. This allows room to assign intermediate sequence numbers to statements that you might want to add later. You can also resequence existing entries in an IPv6 prefix list.

To configure an IPv6 prefix list permit or deny condition, perform the tasks described in Table 10. Enter all commands in IPv6 prefix list configuration mode, unless otherwise noted.

2.6   Configuring Route Maps

When you configure route maps, you configure the route map name, and optionally, associate a description with the route map. You can also assign a sequence number to the route map, and permit or deny routes that use a specific sequence number.

After you create a route map, configure the match conditions that are looked at by the system when sending and receiving routes, and configure the set conditions that determine the action the system takes once a match for a route is found.

To configure route maps, perform the tasks described in the following sections.

2.6.1   Create a Route Map

To create a route map, perform the tasks described in Table 11.

2.6.2   Configure a Match Condition

To configure a match condition, perform the tasks described in Table 12. Enter all commands in route map configuration mode, unless otherwise noted.

2.6.3   Configure a Set Condition

2.7   Configuring BGP Attribute-Based Accounting

Traffic index counters are maintained on interfaces with traffic index accounting enabled. Traffic indexes are associated with BGP routes based on route-maps matching on BGP attributes. When IP packets are received on an interface with traffic index accounting enabled, and the route lookup for the packet’s destination IP address corresponds to a BGP route with a traffic index assigned, the corresponding byte and packet counters are incremented.

To configure BGP attribute-based accounting, perform the tasks described in Table 14.

2.8   Configuring BGP Destination-Based QoS

BGP destination-based quality of service (QoS) provides multiple levels of service based on a customer’s IP destination. BGP routes can be assigned a Differentiated Services Code Point (DSCP) value based on the BGP traffic indexing and table map features associated with route maps. This feature is useful to treat traffic differently depending on which policy it matches.

If the destination of a packet matches a BGP route configured in a route map that contains a set dscp statement, and that route map is enabled via the table-map command in BGP address family configuration mode, and the ingress interface of the packet is enabled via the mark dscp destination command in interface configuration mode, the packet is marked according to the statement defined by the set dscp statement of the route map.

To configure BGP destination-based QoS, perform the tasks described in Table 15.

2.9   Routing Policy Operations

To manage routing policy functions, perform the appropriate tasks described in Table 16. Enter the show commands in any mode; enter the clear and debug commands in exec mode.

3   Configuration Examples

This section provides examples of configuring simple and complex IP prefix lists, AS path lists, and community lists.

3.1   Simple IP Prefix List

The following example configures a simple IP prefix list that allows routes from networks 128.141.1.0/24, 129.142.2.0/24, and 130.143.3.0/24. The last prefix list entry (sequence 40) is optional, because denial is the default action for any prefix not explicitly specified:

[local]Redback(config-ctx)#ip prefix-list simple-prefix-list 

[local]Redback(config-prefix-list)#seq 10 permit 128.141.1.0/24 

[local]Redback(config-prefix-list)#seq 20 permit 129.142.2.0/24 

[local]Redback(config-prefix-list)#seq 30 permit 130.143.3.0/24 

[local]Redback(config-prefix-list)#seq 40 deny 0.0.0.0/0 

The following example applies the IP prefix list, simple-prefix-list, to BGP neighbor, 192.100.100.1, as a BGP inbound route filter:

[local]Redback(config-ctx)#router bgp 100 

[local]Redback(config-bgp)#neighbor 192.100.100.1 external 

[local]Redback(config-neighbor)#address-family ipv4 unicast 

[local]Redback(config-addrfamily)#prefix-list simple-prefix-list in 

3.2   Complex IP Prefix List

This section contains an example of a more complex IP prefix list that allows routes from the following subnetworks:

• Any subnet in the class A network 10 with a prefix length greater than 16 and less than 20
• Any subnet in the class A network 11 with a prefix length exactly equal to 24
• Any subnet or host address in the class A network 12

The IP prefix list configuration is as follows:

[local]Redback(config-ctx)#ip prefix-list complex-prefix-list 

[local]Redback(config-prefix-list)#seq 10 permit 10.0.0.0/8 ge 16 le 20 

[local]Redback(config-prefix-list)#seq 20 permit 11.0.0.0/8 eq 24 

[local]Redback(config-prefix-list)#seq 30 permit 12.0.0.0/8 le 32 

[local]Redback(config-prefix-list)#seq 40 deny 0.0.0.0/0 

The following example applies the complex-prefix-list IP prefix list to BGP neighbor, 192.100.101.5, as a BGP outbound route filter:

[local]Redback(config-ctx)#router bgp 100 

[local]Redback(config-bgp)#neighbor 192.100.101.5 external 

[local]Redback(config-neighbor)#address-family ipv4 unicast 

[local]Redback(config-addrfamily)#prefix-list complex-prefix-list out 

3.3   Simple AS Path List

The following example configures a simple AS path list that denies BGP path attributes starting with AS 100 or ending with AS 200, but allows everything else:

[local]Redback(config-ctx)#as-path-list simple-as-path 

[local]Redback(config-as-path-list)#seq 10 deny ^100 

[local]Redback(config-as-path-list)#seq 20 deny 200$ 

[local]Redback(config-as-path-list)#seq 30 permit any 

The following example applies the AS path list, simple-as-path, to BGP neighbor, 192.100.105.10, as a BGP inbound route filter:

[local]Redback(config-ctx)#router bgp 100 

[local]Redback(config-bgp)#neighbor 192.100.105.10 external 

[local]Redback(config-neighbor)#address-family ipv4 unicast 

[local]Redback(config-addrfamily)#as-path-list simple-as-path in 

3.4   Complex AS Path List

The AS path list example in this section denies:

• Any AS path containing a private AS number (64500–65535)
• Any AS path with AS 100, AS 200, AS 300, or AS 400 anywhere in the sequence
• Any AS path ending in AS 500 or AS 600
• Any AS path starting with 666

The AS path list configuration is as follows:

[local]Redback(config-ctx)#as-path-list complex-as-path 

[local]Redback(config-as-path-list)#seq 10 deny _(65[0-9][0-9][0-9] 
|64[5-9][0-9][0-9])_

[local]Redback(config-as-path-list)#seq 20 deny _(100|200|300|400)_ 

[local]Redback(config-as-path-list)#seq 30 deny (500|600)$ 

[local]Redback(config-as-path-list)#seq 40 deny $666 

[local]Redback(config-as-path-list)#seq 50 permit any 

The following example applies the complex-as-path AS path list to BGP neighbor, 192.100.106.20, as a BGP outbound route filter:

[local]Redback(config-ctx)#router bgp 100 

[local]Redback(config-bgp)#neighbor 192.100.106.20 external 

[local]Redback(config-neighbor)#address-family ipv4 unicast 

[local]Redback(config-addrfamily)#as-path-list complex-as-path out 

3.5   Simple Community List

This following example configures a simple community list that denies community lists containing 10:10, 20:20, or the well-known community no-export (65535:65281), but allows any others:

[local]Redback(config-ctx)#community-list simple-community-list 

[local]Redback(config-community-list)#seq 10 deny 10:10 

[local]Redback(config-community-list)#seq 20 deny 20:20 

[local]Redback(config-community-list)#seq 30 deny no-export 

[local]Redback(config-community-list)#seq 40 permit any 

3.6   Complex Community List

This section contains an example of a complex community list that denies communities with:

• 400 as the first 16 bits (the AS number) and anything for the second 16 bits of the community number
• 500 or 600 as the first 16 bits (the AS number) and 1, 2, or 3 as the second 16 bits of the community number
• The community that maps to the 32-bit quantity 4 billion (4000000000)

The community list configuration is as follows:

[local]Redback(config-ctx)#community-list complex-community-list 

[local]Redback(config-community-list)#seq 10 deny reg-exp _400:[0-9]._ 

[local]Redback(config-community-list)#seq 20 deny reg-exp _(500|600):(1|2|3)_ 

[local]Redback(config-community-list)#seq 30 deny 4000000000 

[local]Redback(config-community-list)#seq 40 permit any 

3.7   Simple Route Map

The following protocol redistribution example configures a simple route map that sets metrics based on network destination address:

[local]Redback(config-ctx)#ip prefix-list select-network-20 

[local]Redback(config-prefix-list)#seq 10 permit 20.0.0.0/8 

[local]Redback(config-prefix-list)#exit 

[local]Redback(config-ctx)#ip prefix-list select-network-30 

[local]Redback(config-prefix-list)#seq 10 permit 30.0.0.0/8 

[local]Redback(config-prefix-list)#exit 

[local]Redback(config-ctx)#route-map proto-redist permit 10 

[local]Redback(config-route-map)#match ip address prefix-list select-network-20 

[local]Redback(config-route-map)#set metric 100 

[local]Redback(config-route-map)#exit 

[local]Redback(config-ctx)#route-map proto-redist permit 20 

[local]Redback(config-route-map)#match ip address prefix-list select-network-30 

[local]Redback(config-route-map)#set metric 200 

The following example applies the proto-redis route map to BGP neighbor, 192.100.105.100, as a BGP inbound route filter:

[local]Redback(config-ctx)#router bgp 100 

[local]Redback(config-bgp)#neighbor 192.100.105.100 external 

[local]Redback(config-neighbor)#address-family ipv4 unicast 

[local]Redback(config-addrfamily)#route-map proto-redist in 

3.8   Complex Route Map

This section contains an example of a complex route map that modifies communities based on AS path lists. For routes corresponding to paths containing private autonomous systems, it will set the community list attribute to the well-known community no-advertise. For routes corresponding to AS paths traversing AS 100, the communities 100:1, 100:2, and 100:3 are added to the BGP community list attribute. This route map and the corresponding communities can be used in conjunction with BGP.

The route map configuration is as follows:

[local]Redback(config-ctx)#as-path-list private-as 

[local]Redback(config-as-path-list)#seq 10 permit _(65[0-9][0-9][0-9]|64[5-9][0-9]
[0-9])_

[local]Redback(config-as-path-list)#exit 

[local]Redback(config-ctx)#as-path-list traverse-100 

[local]Redback(config-as-path-list)#seq 10 permit _100_ 

[local]Redback(config-as-path-list)#exit 

[local]Redback(config-ctx)#route-map modify-community permit 10 

[local]Redback(config-route-map)#match as-path-list private-AS 

[local]Redback(config-route-map)#set community no-advertise 

[local]Redback(config-as-route-map)#exit 

[local]Redback(config-ctx)#route-map modify-community permit 20 

[local]Redback(config-route-map)#match as-path-list traverse-100 

[local]Redback(config-route-map)#set community 100:1 100:2 100:3 additive 

The following example applies the modify-community route map to BGP neighbor, 192.100.106.100, as a BGP outbound route filter:

[local]Redback(config-ctx)#router bgp 100 

[local]Redback(config-bgp)#neighbor 192.100.106.100 external 

[local]Redback(config-neighbor)#address-family ipv4 unicast 

[local]Redback(config-addrfamily)#route-map modify-community out 

3.9   BGP Attribute-Based Accounting

The following example configures BGP attribute-based accounting. Policies are configured to classify the routes which are to be used for BGP policy accounting, and traffic index values are set for routes that pass route map conditions. The bgp-accounting traffic index is assigned to routes installed for the BGP address family. BGP attribute-based accounting is enabled on the interface, joe-customer.

The BGP attribute-based accounting configuration is as follows:

1. Configure policies to classify the routes which are to be used for BGP attribute-based accounting.

[local]Redback(config-ctx)#community-list Customer04 

[local]Redback(config-community-list)#seq 10 permit 200:20 

[local]Redback(config-community-list)#exit 

[local]Redback(config-ctx)#community-list SP-Network 

[local]Redback(config-community-list)#seq 10 permit 200:30 

[local]Redback(config-community-list)#exit 

[local]Redback(config-ctx)#community-list SP-Services 

[local]Redback(config-community-list)#seq 10 permit 200:10 

[local]Redback(config-community-list)#exit 

[local]Redback(config-ctx)#route-map bgp-accounting permit 10 

[local]Redback(config-route-map)#match community-list SP-Services 

[local]Redback(config-route-map)#set traffic-index 1 

[local]Redback(config-route-map)#exit 

[local]Redback(config-ctx)#route-map bgp-accounting permit 20 

[local]Redback(config-route-map)#match community-list Customer04 

[local]Redback(config-route-map)#set traffic-index 2 

[local]Redback(config-route-map)#exit 

[local]Redback(config-ctx)#route-map bgp-accounting permit 30 

[local]Redback(config-route-map)#match community-list SP-Network 

[local]Redback(config-route-map)#set traffic-index 3 

2. Configure table-map to assign a traffic-index to routes installed for a particular BGP address family.

[local]Redback(config-ctx)#router bgp 1 

[local]Redback(config-bgp)#address-family ipv4 unicast 

[local]Redback(config-addrfamily)#table-map bgp-accounting 

3. Enable traffic-index accounting on applicable interface.

[local]Redback(config-ctx)#interface joe-customer 

[local]Redback(config-if)#ip address 10.200.1.1/30 

[local]Redback(config-if)#traffic-index accounting 

3.10   BGP Destination-Based QoS

BGP destination-based QoS supports setting the DSCP byte for IP traffic based on BGP attributes including community list and AS path. This can be used by a service provider (SP) to provide multiple levels of service based on a customers IP destination.

BGP routes can be assigned a DSCP value based on the BGP table-map route-map. When a packet is received on an interface with mark dscp destination enabled and the packet is routed using a route with associated DSCP, the packet's DSCP is updated and the IP header checksum is recalculated.

The BGP destination-based QoS configuration is as follows:

1. Configure policies to classify the routes which are to be used for BGP attribute-based accounting.

[local]Redback(config-ctx)#community-list Bronze-service 

[local]Redback(config-community-list)#seq 10 permit 200:10 

[local]Redback(config-community-list)#exit 

[local]Redback(config-ctx)#community-list Silver-service 

[local]Redback(config-community-list)#seq 10 permit 200:20 

[local]Redback(config-community-list)#exit 

[local]Redback(config-ctx)#community-list Gold-service 

[local]Redback(config-community-list)#seq 10 permit 200:30 

[local]Redback(config-community-list)#exit 

[local]Redback(config-ctx)#route-map destination-qos permit 10 

[local]Redback(config-route-map)#match community-list Gold-service 

[local]Redback(config-route-map)#set dscp ef 

[local]Redback(config-route-map)#exit 

[local]Redback(config-ctx)#route-map destination-qos permit 20 

[local]Redback(config-route-map)#match community-list Silver-service 

[local]Redback(config-route-map)#set dscp af11 

[local]Redback(config-route-map)#exit 

[local]Redback(config-ctx)#route-map destination-qos permit 20 

[local]Redback(config-route-map)#match community-list Bronze-service 

[local]Redback(config-route-map)#set dscp df 

2. Configure table-map to assign a DSCP to routes installed for a particular BGP address family.

[local]Redback(config-ctx)#router bgp 1 

[local]Redback(config-bgp)#address-family ipv4 unicast 

[local]Redback(config-addrfamily)#table-map destination-qos 

3. Enable mark dscp destination on applicable interface.

[local]Redback(config-ctx)#interface jane-customer 

[local]Redback(config-if)#ip address 10.200.1.1/30 

[local]Redback(config-if)#mark dscp destination