BGP per Neighbor SoO Configuration

The BGP per Neighbor SoO Configuration feature simplifies the configuration of the site-of-origin (SoO) value. Per neighbor SoO configuration introduces two new commands that can be configured in submodes under router configuration mode to set the SoO value.

Prerequisites for BGP per Neighbor SoO Configuration

This feature assumes that a Border Gateway Protocol (BGP) network is configured and that Cisco Express Forwarding is enabled in your network.

Restrictions for BGP per Neighbor SoO Configuration

A BGP neighbor or peer policy template-based SoO configuration takes precedence over the SoO value configured in an inbound route map.

Information About Configuring BGP per Neighbor SoO

Site of Origin BGP Community Attribute

The site-of-origin (SoO) extended community is a BGP extended community attribute that is used to identify routes that have originated from a site so that the readvertisement of that prefix back to the source site can be prevented. The SoO extended community uniquely identifies the site from which a router has learned a route. BGP can use the SoO value associated with a route to prevent routing loops.

Route Distinguisher

A route distinguisher (RD) creates routing and forwarding tables and specifies the default route distinguisher for a VPN. The RD is added to the beginning of an IPv4 prefix to change it into a globally unique VPN-IPv4 prefix. An RD can be composed in one of two ways: with an autonomous system number and an arbitrary number or with an IP address and an arbitrary number.

You can enter an RD in either of these formats:

  • Enter a 16-bit autonomous system number, a colon, and a 32-bit number. For example:

45000:3

  • Enter a 32-bit IP address, a colon, and a 16-bit number. For example:

192.168.10.15:1

BGP per Neighbor Site of Origin Configuration

There are three ways to configure an SoO value for a BGP neighbor:

  • BGP peer policy template--A peer policy template is created, and an SoO value is configured as part of the peer policy. Under address family IPv4 VRF, a neighbor is identified and is configured to inherit the peer policy that contains the SoO value.

  • BGP neighbor command--Under address family IPv4 VRF, a neighbor is identified, and an SoO value is configured for the neighbor.

  • BGP peer group--Under address family IPv4 VRF, a BGP peer group is configured, an SoO value is configured for the peer group, a neighbor is identified, and the neighbor is configured as a member of the peer group.


Note

A BGP neighbor or peer policy template-based SoO configuration takes precedence over the SoO value configured in an inbound route map.

The configuration of SoO values for BGP neighbors is performed on a provider edge (PE) router, which is the VPN entry point. When SoO is enabled, the PE router forwards prefixes to the customer premises equipment (CPE) only when the SoO tag of the prefix does not match the SoO tag configured for the CPE.

For example, in the figure below, an SoO tag is set as 65000:1 for the customer site that includes routers CPE1 and CPE2 with an autonomous system number of 65000. When CPE1 sends prefixes to PE1, PE1 tags the prefixes with 65000:1, which is the SoO tag for CPE1 and CPE2. When PE1 sends the tagged prefixes to PE2, PE2 performs a match against the SoO tag from CPE2. Any prefixes with the tag value of 65000:1 are not sent to CPE2 because the SoO tag matches the SoO tag of CPE2, and a routing loop is avoided.

Figure 1. Network Diagram for SoO Example

Benefits of BGP per Neighbor Site of Origin

In releases prior to the introduction of this feature, the SoO extended community attribute is configured using an inbound route map that sets the SoO value during the update process. With the introduction of the BGP per Neighbor Site of Origin feature, two new commands configured in submodes under router configuration mode simplify the SoO value configuration.

BGP Peer Policy Templates

Peer policy templates are used to configure BGP policy commands that are configured for neighbors that belong to specific address families. Peer policy templates are configured once and then applied to many neighbors through the direct application of a peer policy template or through inheritance from peer policy templates. The configuration of peer policy templates simplifies the configuration of BGP policy commands that are applied to all neighbors within an autonomous system.

Peer policy templates support inheritance. A directly applied peer policy template can directly or indirectly inherit configurations from up to seven peer policy templates. So, a total of eight peer policy templates can be applied to a neighbor or neighbor group.

The configuration of peer policy templates simplifies and improves the flexibility of BGP configuration. A specific policy can be configured once and referenced many times. Because a peer policy supports up to eight levels of inheritance, very specific and very complex BGP policies can be created.

For more details about BGP peer policy templates, see the "Configuring a Basic BGP Network" module.

How to Configure BGP per Neighbor SoO

Enabling Cisco Express Forwarding and Configuring VRF Instances

Perform this task on both of the PE routers in the figure above to configure Virtual Routing and Forwarding (VRF) instances to be used with the per-VRF assignment tasks. In this task, Cisco Express Forwarding is enabled, and a VRF instance named SOO_VRF is created. To make the VRF functional, a route distinguisher is created, and the VRF is associated with an interface. When the route distinguisher is created, the routing and forwarding tables are created for the VRF instance named SOO_VRF. After associating the VRF with an interface, the interface is configured with an IP address.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. ip cef
  4. ip vrf vrf-name
  5. rd route-distinguisher
  6. route-target {export | both } route-target-ext-community
  7. route-target {import | both } route-target-ext-community
  8. exit
  9. interface type number
  10. ip vrf forwarding vrf-name [downstream vrf-name2 ]
  11. ip address ip-address mask [secondary ]
  12. end
  13. show ip vrf [brief | detail | interfaces | id ] [vrf-name ] [output-modifiers ]

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

ip cef

Example:


Device(config)# ip cef

Enables Cisco Express Forwarding on the route processor.

Step 4

ip vrf vrf-name

Example:


Device(config)# ip vrf SOO_VRF

Defines a VRF instance and enters VRF configuration mode.

Step 5

rd route-distinguisher

Example:


Device(config-vrf)# rd 1:1

Creates routing and forwarding tables for a VRF and specifies the default RD for a VPN.

  • Use the route-distinguisher argument to specify the default RD for a VPN. There are two formats that you can use to specify an RD:
    • A 16-bit autonomous system number, a colon, and a 32-bit number, for example: 65000:3
    • A 32-bit IP address, a colon, and a 16-bit number, for example: 192.168.1.2:51

  • In this example, the RD uses an autonomous system number with the number 1 after the colon.

Step 6

route-target {export | both } route-target-ext-community

Example:


Device(config-vrf)# route-target export 1:1

Creates a route-target extended community for a VRF.

  • Use the export keyword to export routing information to the target VPN extended community.

  • Use the both keyword to both import routing information from, and export routing information to, the target VPN extended community.

  • Use the route-target-ext-community argument to specify the VPN extended community.

Note

 

Only the syntax applicable to this step is displayed. For a different use of this syntax, see Step 7.

Step 7

route-target {import | both } route-target-ext-community

Example:


Device(config-vrf)# route-target import 1:1

Creates a route-target extended community for a VRF.

  • Use the import keyword to import routing information from the target VPN extended community.

  • Use the both keyword to both import routing information from, and export routing information to, the target VPN extended community.

  • Use the route-target-ext-community argument to specify the VPN extended community.

Step 8

exit

Example:


Device(config-vrf)# exit

Exits VRF configuration mode and returns to global configuration mode.

Step 9

interface type number

Example:


Device(config)# interface GigabitEthernet 1/0/0

Configures an interface type and enters interface configuration mode.

Step 10

ip vrf forwarding vrf-name [downstream vrf-name2 ]

Example:


Device(config-if)# ip vrf forwarding SOO_VRF

Associates a VRF with an interface or subinterface.

  • In this example, the VRF named SOO_VRF is associated with Gigabit Ethernet interface 1/0/0.

Note

 

Executing this command on an interface removes the IP address, so the IP address should be reconfigured.

Step 11

ip address ip-address mask [secondary ]

Example:


Device(config-if)# ip address 192.168.1.2 255.255.255.0

Configures an IP address.

  • In this example, Gigabit Ethernet interface 1/0/0 is configured with an IP address of 192.168.1.2.

Step 12

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Step 13

show ip vrf [brief | detail | interfaces | id ] [vrf-name ] [output-modifiers ]

Example:


Device# show ip vrf

Displays the configured VRFs.

  • Use this command to verify the configuration of this task.

Examples

The following output of the show ip vrf command displays the VRF named SOO_VRF configured in this task. 


Device# show ip vrf

Name                             Default RD            Interfaces
SOO_VRF                                 1:1                GE1/0/0

Configuring a per Neighbor SoO Value Using a BGP Peer Policy Template

Perform this task on router PE1 in the figure above to configure an SoO value for a BGP neighbor at the router CPE1 in the figure above using a peer policy template. In this task, a peer policy template is created, and the SoO value is configured for the peer policy. Under address family IPv4 VRF, a neighbor is identified and is configured to inherit the peer policy that contains the SoO value.

If a BGP peer inherits from several peer policy templates that specify different SoO values, the SoO value in the last template applied takes precedence and is applied to the peer. However, direct configuration of the SoO value on the BGP neighbor overrides any inherited template configurations of the SoO value.

Before you begin

This task assumes that the task described in the Enabling Cisco Express Forwarding and Configuring VRF Instances has been performed.


Note

A BGP peer cannot inherit from a peer policy or session template and be configured as a peer group member at the same. BGP templates and BGP peer groups are mutually exclusive.

>

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. router bgp autonomous-system-number
  4. template peer-policy policy-template-name
  5. soo extended-community-value
  6. exit-peer-policy
  7. address-family ipv4 [unicast | multicast | vrf vrf-name ]
  8. neighbor ip-address remote-as autonomous-system-number
  9. neighbor ip-address activate
  10. neighbor ip-address inherit peer-policy policy-template-name
  11. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Router> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Router# configure terminal

Enters global configuration mode.

Step 3

router bgp autonomous-system-number

Example:


Router(config)# router bgp 50000

Enters router configuration mode for the specified routing process.

Step 4

template peer-policy policy-template-name

Example:


Router(config-router)# template peer-policy SOO_POLICY

Creates a peer policy template and enters policy-template configuration mode.

Step 5

soo extended-community-value

Example:


Router(config-router-ptmp)# soo 65000:1

Sets the SoO value for a BGP peer policy template.

  • Use the extended-community-value argument to specify the VPN extended community value. The value takes one of the following formats:
    • A 16-bit autonomous system number, a colon, and a 32-bit number, for example: 45000:3
    • A 32-bit IP address, a colon, and a 16-bit number, for example: 192.168.10.2:51

  • In this example, the SoO value is set at 65000:1.

Step 6

exit-peer-policy

Example:


Router(config-router-pmtp)# exit-peer-policy

Exits policy-template configuration mode and returns to router configuration mode.

Step 7

address-family ipv4 [unicast | multicast | vrf vrf-name ]

Example:


Router(config-router)# address-family ipv4 vrf SOO_VRF

Specifies the IPv4 address family and enters address family configuration mode.

  • Use the unicast keyword to specify the IPv4 unicast address family. By default, the router is placed in configuration mode for the IPv4 unicast address family if the unicast keyword is not specified with the address-family ipv4 command.

  • Use the multicast keyword to specify IPv4 multicast address prefixes.

  • Use the vrf keyword and vrf-name argument to specify the name of the VRF instance to associate with subsequent IPv4 address family configuration mode commands.

Step 8

neighbor ip-address remote-as autonomous-system-number

Example:


Router(config-router-af)# neighbor 192.168.1.1 remote-as 65000

Adds the IP address of the neighbor in the specified autonomous system to the IPv4 multiprotocol BGP neighbor table of the local router.

Step 9

neighbor ip-address activate

Example:


Router(config-router-af)# neighbor 192.168.1.1 activate

Enables the neighbor to exchange prefixes for the IPv4 VRF address family with the local router.

Step 10

neighbor ip-address inherit peer-policy policy-template-name

Example:


Router(config-router-af)# neighbor 192.168.1.1 inherit peer-policy SOO_POLICY

Sends a peer policy template to a neighbor so that the neighbor can inherit the configuration.

  • In this example, the router is configured to send the peer policy template named SOO_POLICY to the 192.168.1.1 neighbor to inherit. If another peer policy template is indirectly inherited from SOO_POLICY, the indirectly inherited configuration will also be applied. Up to seven additional peer policy templates can be indirectly inherited from SOO_POLICY.

Step 11

end

Example:


Router(config-router-af)# end

Exits address family configuration mode and returns to privileged EXEC mode.

Configuring a per Neighbor SoO Value Using a BGP neighbor Command

Perform this task on router PE2 in the figure above to configure an SoO value for the BGP neighbor at router CPE2 in the figure above using a neighbor command. For the IPv4 VRF address family, a neighbor is identified, and an SoO value is configured for the neighbor.

Direct configuration of the SoO value on a BGP neighbor overrides any inherited peer policy template configurations of the SoO value.

Before you begin

This task assumes that the task described in the “Verifying CEF and Configuring VRF Instances” section has been performed with appropriate changes to interfaces and IP addresses.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. router bgp autonomous-system-number
  4. address-family ipv4 [unicast | multicast | vrf vrf-name ]
  5. neighbor {ip-address | peer-group-name } remote-as autonomous-system-number
  6. neighbor ip-address activate
  7. neighbor {ip-address | peer-group-name } soo extended-community-value
  8. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

router bgp autonomous-system-number

Example:


Device(config)# router bgp 50000

Enters router configuration mode for the specified routing process.

Step 4

address-family ipv4 [unicast | multicast | vrf vrf-name ]

Example:


Device(config-router)# address-family ipv4 vrf SOO_VRF

Specifies the IPv4 address family and enters address family configuration mode.

  • Use the unicast keyword to specify the IPv4 unicast address family. By default, the router is placed in configuration mode for the IPv4 unicast address family if the unicast keyword is not specified with the address-family ipv4 command.

  • Use the multicast keyword to specify IPv4 multicast address prefixes.

  • Use the vrf keyword and vrf-name argument to specify the name of the VRF instance to associate with subsequent IPv4 address family configuration mode commands.

Step 5

neighbor {ip-address | peer-group-name } remote-as autonomous-system-number

Example:


Device(config-router-af)# neighbor 192.168.2.1 remote-as 65000

Adds the IP address of the neighbor in the specified autonomous system to the IPv4 multiprotocol BGP neighbor table of the local router.

Step 6

neighbor ip-address activate

Example:


Device(config-router-af)# neighbor 192.168.2.1 activate

Enables the neighbor to exchange prefixes for the IPv4 VRF address family with the local router.

  • In this example, the external BGP peer at 192.168.2.1 is activated.

Note

 

If a peer group has been configured in Step 5 , do not use this step because BGP peer groups are activated when any parameter is configured. For example, a BGP peer group is activated when an SoO value is configured using the neighbor soo command in Step 7.

Step 7

neighbor {ip-address | peer-group-name } soo extended-community-value

Example:


Device(config-router-af)# neighbor 192.168.2.1 soo 65000:1

Sets the site-of-origin (SoO) value for a BGP neighbor or peer group.

  • In this example, the neighbor at 192.168.2.1 is configured with an SoO value of 65000:1.

Step 8

end

Example:


Device(config-router-af)# end

Exits address family configuration mode and returns to privileged EXEC mode.

Configuring a per Neighbor SoO Value Using a BGP Peer Group

Perform this task on router PE1 in the figure above to configure an SoO value for the BGP neighbor at router CPE1 in the figure above using a neighbor command with a BGP peer group. Under address family IPv4 VRF, a BGP peer group is created and an SoO value is configured using a BGP neighbor command, and a neighbor is then identified and added as a peer group member. A BGP peer group member inherits the configuration associated with a peer group, which in this example, includes the SoO value.

Direct configuration of the SoO value on a BGP neighbor overrides any inherited peer group configurations of the SoO value.

Before you begin

This task assumes that the task described in “Enabling Cisco Express Forwarding and Configuring VRF Instances” has been performed.


Note

A BGP peer cannot inherit from a peer policy or session template and be configured as a peer group member at the same. BGP templates and BGP peer groups are mutually exclusive.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. router bgp autonomous-system-number
  4. address-family ipv4 [unicast | multicast | vrf vrf-name ]
  5. neighbor peer-group-name peer-group
  6. neighbor {ip-address | peer-group-name } soo extended-community-value
  7. neighbor ip-address remote-as autonomous-system-number
  8. neighbor ip-address activate
  9. neighbor ip-address peer-group peer-group-name
  10. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

router bgp autonomous-system-number

Example:


Device(config)# router bgp 50000

Enters router configuration mode for the specified routing process.

Step 4

address-family ipv4 [unicast | multicast | vrf vrf-name ]

Example:


Device(config-router)# address-family ipv4 vrf SOO_VRF

Specifies the IPv4 address family and enters address family configuration mode.

  • Use the unicast keyword to specify the IPv4 unicast address family. By default, the router is placed in configuration mode for the IPv4 unicast address family if the unicast keyword is not specified with the address-family ipv4 command.

  • Use the multicast keyword to specify IPv4 multicast address prefixes.

  • Use the vrf keyword and vrf-name argument to specify the name of the VRF instance to associate with subsequent IPv4 address family configuration mode commands.

Step 5

neighbor peer-group-name peer-group

Example:


Device(config-router-af)# neighbor SOO_group peer-group

Creates a BGP peer group.

Step 6

neighbor {ip-address | peer-group-name } soo extended-community-value

Example:


Device(config-router-af)# neighbor SOO_group soo 65000:1

Sets the site-of-origin (SoO) value for a BGP neighbor or peer group.

  • In this example, the BGP peer group, SOO_group, is configured with an SoO value of 65000:1.

Step 7

neighbor ip-address remote-as autonomous-system-number

Example:


Device(config-router-af)# neighbor 192.168.1.1 remote-as 65000

Adds the IP address of the neighbor in the specified autonomous system to the IPv4 multiprotocol BGP neighbor table of the local router.

Step 8

neighbor ip-address activate

Example:


Device(config-router-af)# neighbor 192.168.1.1 activate

Enables the neighbor to exchange prefixes for the IPv4 VRF address family with the local router.

Step 9

neighbor ip-address peer-group peer-group-name

Example:


Device(config-router-af)# neighbor 192.168.1.1 peer-group SOO_group

Assigns the IP address of a BGP neighbor to a peer group.

Step 10

end

Example:


Device(config-router-af)# end

Exits address family configuration mode and returns to privileged EXEC mode.

Configuration Examples for BGP per Neighbor SoO Configuration

Example: Configuring a per Neighbor SoO Value Using a BGP Peer Policy Template

The following example shows how to create a peer policy template and configure an SoO value as part of the peer policy. After enabling Cisco Express Forwarding and configuring a VRF instance named SOO_VRF, a peer policy template is created and an SoO value is configured as part of the peer policy. Under the IPv4 VRF address family, a neighbor is identified and configured to inherit the peer policy that contains the SoO value. 


ip cef
ip vrf SOO_VRF
 rd 1:1
 route-target export 1:1
 route-target import 1:1
 exit
interface GigabitEthernet 1/0/0
 ip vrf forwarding SOO_VRF
 ip address 192.168.1.2 255.255.255.0
 exit
router bgp 50000
 template peer-policy SOO_POLICY
  soo 65000:1
  exit-peer-policy
 address-family ipv4 vrf SOO_VRF
  neighbor 192.168.1.1 remote-as 65000
  neighbor 192.168.1.1 activate
  neighbor 192.168.1.1 inherit peer-policy SOO_POLICY
  end

Example: Configuring a per Neighbor SoO Value Using a BGP neighbor Command

The following example shows how to configure an SoO value for a BGP neighbor. After enabling Cisco Express Forwarding and configuring a VRF instance named SOO_VRF, a neighbor is identified in the IPv4 VRF address family and an SoO value is configured for the neighbor. 


ip cef
ip vrf SOO_VRF
 rd 1:1
 route-target export 1:1
 route-target import 1:1
 exit
interface GigabitEthernet 1/0/0
 ip vrf forwarding SOO_VRF
 ip address 192.168.2.2 255.255.255.0
 exit
router bgp 50000
 address-family ipv4 vrf SOO_VRF
  neighbor 192.168.2.1 remote-as 65000
  neighbor 192.168.2.1 activate
  neighbor 192.168.2.1 soo 65000:1
  end

Example: Configuring a per Neighbor SoO Value Using a BGP Peer Group

The following example shows how to configure an SoO value for a BGP peer group. After enabling Cisco Express Forwarding and configuring a VRF instance named SOO_VRF, a BGP peer group is configured in the IPv4 VRF address family, an SoO value is configured for the peer group, a neighbor is identified, and the neighbor is configured as a member of the peer group. 


ip cef
ip vrf SOO_VRF
 rd 1:1
 route-target export 1:1
 route-target import 1:1
 exit
interface GigabitEthernet 1/0/0
 ip vrf forwarding SOO_VRF
 ip address 192.168.1.2 255.255.255.0
 exit
router bgp 50000
 address-family ipv4 vrf SOO_VRF
  neighbor SOO_GROUP peer-group
  neighbor SOO_GROUP soo 65000:65
  neighbor 192.168.1.1 remote-as 65000
  neighbor 192.168.1.1 activate
  neighbor 192.168.1.1 peer-group SOO_GROUP 
  end

Where to Go Next

  • To read an overview of BGP, proceed to the "Cisco BGP Overview" module.

  • To perform basic BGP feature tasks, proceed to the "Configuring a Basic BGP Network" module.

  • To perform advanced BGP feature tasks, proceed to the "Configuring Advanced BGP Features" module.

  • To configure BGP neighbor session options, proceed to the "Configuring BGP Neighbor Session Options" module.

  • To perform internal BGP tasks, proceed to the "Configuring Internal BGP Features" module.

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

BGP commands

Cisco IOS IP Routing: BGP Command Reference

IP Switching commands

Cisco IOS IP Switching Command Reference

MIBs

MIB

MIBs Link

—

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for BGP per Neighbor SoO Configuration

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1. Feature Information for BGP per Neighbor SoO Configuration

Feature Name

Releases

Feature Information

BGP per Neighbor SoO Configuration

Cisco IOS XE Release 2.1

The BGP per neighbor SOO configuration feature simplifies the configuration of the site-of-origin (SoO) parameter. The per neighbor SoO configuration introduces two new commands that can be configured in submodes under router configuration mode to set the SoO value.

This feature was introduced on the Cisco ASR 1000 Series Aggregation Services Routers.

The following commands were introduced by this feature: neighbor soo , soo .