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Table Of Contents
BGP per Neighbor SoO Configuration
Prerequisites for BGP per Neighbor SoO Configuration
Restrictions for BGP per Neighbor SoO Configuration
Information About Configuring BGP per Neighbor SoO
Site of Origin BGP Community Attribute
BGP Support for 4-Byte Autonomous System Numbers
BGP per Neighbor Site of Origin Configuration
Benefits of BGP per Neighbor Site of Origin
How to Configure BGP per Neighbor SoO
Verifying CEF and Configuring VRF Instances
Configuring a per Neighbor SoO Value Using a BGP Peer Policy Template
Configuring a per Neighbor SoO Value Using a BGP neighbor Command
Configuring a per Neighbor SoO Value Using a BGP Peer Group
Configuration Examples for BGP per Neighbor SoO Configuration
Configuring a per Neighbor SoO Value Using a BGP Peer Policy Template: Example
Configuring a per Neighbor SoO Value Using a BGP neighbor Command: Example
Configuring a per Neighbor SoO Value Using a BGP Peer Group: Example
Feature Information for BGP per Neighbor SoO Configuration
BGP per Neighbor SoO Configuration
First Published: November 17, 2006Last Updated: February 27, 2009The BGP per Neighbor SoO Configuration feature simplifies the configuration of the site-of-origin (SoO) value. In Cisco IOS Release 12.4(9)T, 12.2(33)SRA, 12.2(31)SB2, and previous releases, the SoO value is configured using an inbound route map that sets the SoO value during the update process. Per neighbor SoO configuration introduces two new commands that can be configured in submodes under router configuration mode to set the SoO value. In Cisco IOS Release 12.4(24)T, support was added for 4-byte autonomous system numbers in asdot format only.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for BGP per Neighbor SoO Configuration" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
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Prerequisites for BGP per Neighbor SoO Configuration
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Prerequisites for BGP per Neighbor SoO Configuration
This feature assumes that a Border Gateway Protocol (BGP) network is configured and that Cisco Express Forwarding (CEF) 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
Before configuring SoO values for BGP neighbors, you should understand the following concepts:
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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.
BGP Support for 4-Byte Autonomous System Numbers
In Cisco IOS Release 12.4(24)T, support was added for 4-byte autonomous system numbers as described in RFC 5396, Textual Representation of Autonomous System (AS) Numbers. In Cisco IOS Release 12.4(24)T, the Cisco implementation of 4-byte autonomous system numbers uses asdot notation—1.2 for example—as the only configuration format, regular expression match, and output display, with no asplain support.
For configuration examples involving 4-byte autonomous system numbers, see the "Configuring a per Neighbor SoO Value with a 4-Byte Autonomous System Number Using a BGP Peer Policy Template: Example" section or the "Configuring a per Neighbor SoO Value Using a BGP neighbor Command and 4-Byte Autonomous System Numbers: Example" section.
For more details about the Cisco implementation of BGP autonomous system number formats, see the the "Cisco BGP Overview" module.
BGP per Neighbor Site of Origin Configuration
There are three ways to configure an SoO value for a BGP neighbor:
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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 Figure 1, 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 Cisco IOS Release 12.4(11)T, 12.2(33)SRB, and 12.2(33)SB, the SoO extended community attribute is configured using an inbound route map that sets the SoO value during the update process. The introduction of two new commands configured in submodes under router configuration mode simplifies the SoO value configuration.
How to Configure BGP per Neighbor SoO
To configure an SoO value for a BGP neighbor, you must perform the first task in the following list and one of the next three tasks. The last three tasks are mutually exclusive; you need perform only one of them.
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Verifying CEF and Configuring VRF Instances
Perform this task on both of the PE routers in Figure 1 to configure Virtual Routing and Forwarding (VRF) instances to be used with the per-VRF assignment tasks. In this task, After checking that CEF is enabled, a VRF instance named SOO_VRF is configured. 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.
Route Distinguisher
A router 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:
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45000:3
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192.168.10.15:1
SUMMARY STEPS
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DETAILED STEPS
Step 1
enable
Example:Router> enable
Enables privileged EXEC mode.
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Step 2
show ip cef
Example:Router# show ip cef
Verifies that CEF is enabled.
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Step 3
configure terminal
Example:Router# configure terminal
Enters global configuration mode.
Step 4
ip vrf vrf-name
Example:Router(config)# ip vrf SOO_VRF
Defines a VRF instance and enters VRF configuration mode.
Step 5
rd route-distinguisher
Example:Router(config-vrf)# rd 1:1
Creates routing and forwarding tables for a VRF and specifies the default RD for a VPN.
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Step 6
route-target {export | both} route-target-ext-community
Example:Router(config-vrf)# route-target export 1:1
Creates a route-target extended community for a VRF.
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route-target {import | both} route-target-ext-community
Example:Router(config-vrf)# route-target import 1:1
Creates a route-target extended community for a VRF.
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Step 8
exit
Example:Router(config-vrf)# exit
Exits VRF configuration mode and returns to global configuration mode.
Step 9
interface type number
Example:Router(config)# interface Ethernet 1/0
Configures an interface type and enters interface configuration mode.
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Step 10
ip vrf forwarding vrf-name [downstream vrf-name2]
Example:Router(config-if)# ip vrf forwarding SOO_VRF
Associates a VRF with an interface or subinterface.
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ip address ip-address mask [secondary]
Example:Router(config-if)# ip address 192.168.1.2 255.255.255.0
Configures an IP address.
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Step 12
end
Example:Router(config-if)# end
Exits interface configuration mode and returns to privileged EXEC mode.
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show ip vrf [brief | detail | interfaces | id] [vrf-name] [output-modifiers]
Example:Router# show ip vrf
Displays the configured VRFs.
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Examples
The following output of the show ip vrf command displays the VRF named SOO_VRF configured in this task.
Router# show ip vrfName Default RD InterfacesSOO_VRF 1:1 Eth1/0Configuring a per Neighbor SoO Value Using a BGP Peer Policy Template
Perform this task on router PE1 in Figure 1 to configure an SoO value for a BGP neighbor at the router CPE1 in Figure 1 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.
For a configuration example involving 4-byte autonomous system numbers, see the "Configuring a per Neighbor SoO Value with a 4-Byte Autonomous System Number Using a BGP Peer Policy Template: Example" section.
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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.
Prerequisites
This task assumes that the task described in the "Verifying CEF and Configuring VRF Instances" section has been performed.
Restrictions
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.
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DETAILED STEPS
Configuring a per Neighbor SoO Value Using a BGP neighbor Command
Perform this task on router PE2 in Figure 1 to configure an SoO value for the BGP neighbor at router CPE2 in Figure 1 using a neighbor command. Under address family IPv4 VRF, a neighbor is identified, and an SoO value is configured for the neighbor.
For a configuration example involving 4-byte autonomous system numbers, see the "Configuring a per Neighbor SoO Value Using a BGP neighbor Command and 4-Byte Autonomous System Numbers: Example" section.
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Prerequisites
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
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DETAILED STEPS
Step 1
enable
Example:Router> enable
Enables privileged EXEC mode.
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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
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.
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Step 5
neighbor {ip-address | peer-group-name} remote-as autonomous-system-number
Example:Router(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:Router(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.
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neighbor {ip-address | peer-group-name} soo extended-community-value
Example:Router(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.
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Step 8
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 Peer Group
Perform this task on router PE1 in Figure 1 to configure an SoO value for the BGP neighbor at router CPE1 in Figure 1 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.
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Prerequisites
This task assumes that the task described in the "Verifying CEF and Configuring VRF Instances" section has been performed.
Restrictions
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
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DETAILED STEPS
Configuration Examples for BGP per Neighbor SoO Configuration
This section contains the following configuration examples:
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Configuring a per Neighbor SoO Value Using a BGP Peer Policy Template: Example
The following example shows how to create a peer policy template and configure an SoO value as part of the peer policy. After verifying that CEF is enabled 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 address family IPv4 VRF, a neighbor is identified and configured to inherit the peer policy that contains the SoO value.
show ip cefip vrf SOO_VRFrd 1:1route-target export 1:1route-target import 1:1exitinterface Ethernet 1/0ip vrf forwarding SOO_VRFip address 192.168.1.2 255.255.255.0exitrouter bgp 50000template peer-policy SOO_POLICYsoo 65000:1exit-peer-policyaddress-family ipv4 vrf SOO_VRFneighbor 192.168.1.1 remote-as 65000neighbor 192.168.1.1 activateneighbor 192.168.1.1 inherit peer-policy SOO_POLICYendConfiguring a per Neighbor SoO Value with a 4-Byte Autonomous System Number Using a BGP Peer Policy Template: Example
The following example shows how to create a peer policy template and configure an SoO value using a 4-byte autonomous system number, 1.2 in asdot format, as part of the peer policy. Under address family IPv4 VRF, a neighbor is identified and configured to inherit the peer policy that contains the SoO value. This example requires Cisco IOS Release 12.4(24)T, or a later release.
router bgp 1.2template peer-policy SOO_POLICYsoo 1.2:3exit-peer-policyaddress-family ipv4 vrf SOO_VRFneighbor 192.168.3.2 remote-as 1.14neighbor 192.168.3.2 activateneighbor 192.168.3.2 inherit peer-policy SOO_POLICYendConfiguring a per Neighbor SoO Value Using a BGP neighbor Command: Example
The following example shows how to configure an SoO value for a BGP neighbor. After checking that CEF is enabled, a VRF instance named SOO_VRF is configured, a neighbor is identified under address family IPv4 VRF, and an SoO value is configured for the neighbor.
show ip cefip vrf SOO_VRFrd 1:1route-target export 1:1route-target import 1:1exitinterface Ethernet 1/0ip vrf forwarding SOO_VRFip address 192.168.2.2 255.255.255.0exitrouter bgp 50000address-family ipv4 vrf SOO_VRFneighbor 192.168.2.1 remote-as 65000neighbor 192.168.2.1 activateneighbor 192.168.2.1 soo 65000:1endConfiguring a per Neighbor SoO Value Using a BGP neighbor Command and 4-Byte Autonomous System Numbers: Example
The following example shows how to configure an SoO value for a BGP neighbor. In this example, all BGP neighbors, route targets, and SoO values use 4-byte autonomous system numbers in asplain format. After checking that CEF is enabled, a VRF instance named SOO_VRF is configured with route targets. In a BGP router session a neighbor is identified under address family IPv4 VRF, and an SoO value is configured for the neighbor. This example requires Cisco IOS Release 12.4(24)T, or a later release.
show ip cefip vrf SOO_VRFrd 100:200route-target export 1.14:1route-target import 1.14:1exitinterface Ethernet 1/0ip vrf forwarding SOO_VRFip address 192.168.2.2 255.255.255.0exitrouter bgp 1.2address-family ipv4 vrf SOO_VRFneighbor 192.168.2.1 remote-as 1.14neighbor 192.168.2.1 activateneighbor 192.168.2.1 soo 1.14:1endConfiguring a per Neighbor SoO Value Using a BGP Peer Group: Example
The following example shows how to configure an SoO value for a BGP peer group. After checking that CEF is enabled, a VRF instance named SOO_VRF is configured, a BGP peer group is configured under address family IPv4 VRF, 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.
show ip cefip vrf SOO_VRFrd 1:1route-target export 1:1route-target import 1:1exitinterface Ethernet 1/0ip vrf forwarding SOO_VRFip address 192.168.1.2 255.255.255.0exitrouter bgp 50000address-family ipv4 vrf SOO_VRFneighbor SOO_GROUP peer-groupneighbor SOO_GROUP soo 65000:65neighbor 192.168.1.1 remote-as 65000neighbor 192.168.1.1 activateneighbor 192.168.1.1 peer-group SOO_GROUPendWhere to Go Next
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Additional References
The following sections provide references related to the BGP support for per neighbor SoO configuration feature.
Related Documents
MIBs
Technical Assistance
Command Reference
The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS IP Routing Protocols Command Reference at http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_book.html. For information about all Cisco IOS commands, use the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or the Cisco IOS Master Command List, All Releases, at http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html.
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Feature Information for BGP per Neighbor SoO Configuration
Table 1 lists the release history for this feature.
For information on a feature in this technology that is not documented here, see the "BGP Features Roadmap."
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
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Table 1 Feature Information for BGP per Neighbor SoO Configuration
BGP per Neighbor SoO Configuration
12.2(33)SB
12.2(33)SRB
12.4(11)TThe BGP per neighbor SOO configuration feature simplifies the configuration of the site-of-origin (SoO) parameter. In Cisco IOS Release 12.4(9)T, 12.2(33)SRA, 12.2(31)SB2, and previous releases, the SoO parameter is configured using an inbound route map that sets the SoO value during the update process. The per neighbor SoO configuration introduces two new commands that can be configured in submodes under router configuration mode to set the SoO value.
The following commands were introduced by this feature: neighbor soo, soo.
BGP Support for 4-Byte ASN
12.0(32)S12
12.0(32)SY8
12.4(24)TThe BGP Support for 4-Byte ASN feature introduced support for 4-byte autonomous system numbers. Because of increased demand for autonomous system numbers, in January 2009 the IANA will start to allocate 4-byte autonomous system numbers in the range from 65536 to 4294967295.
In Cisco IOS Release 12.0(32)SY8, the Cisco implementation of 4-byte autonomous system numbers uses asplain as the default regular expression match and output display format for autonomous system numbers, but you can configure 4-byte autonomous system numbers in both the asplain format and the asdot format as described in RFC 5396. To change the default regular expression match and output display of 4-byte autonomous system numbers to asdot format, use the bgp asnotation dot command.
In Cisco IOS Release 12.0(32)S12, and 12.4(24)T, the Cisco implementation of 4-byte autonomous system numbers uses asdot as the only configuration format, regular expression match, and output display, with no asplain support.
The following sections provide information about this feature:
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The following commands were modified by this feature: bgp asnotation dot, bgp confederation identifier, bgp confederation peers, clear ip bgp, ip bgp-community new-format, ip extcommunity-list, match source-protocol, neighbor local-as, neighbor remote-as, redistribute (IP), router bgp, set as-path, set extcommunity, set origin, and all show ip bgp commands that display an autonomous system number.
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