Per-VRF Assignment of BGP Router ID

The Per-VRF Assignment of BGP Router ID feature introduces the ability to have VRF-to-VRF peering in Border Gateway Protocol (BGP) on the same router. BGP is designed to refuse a session with itself because of the router ID check. The per-VRF assignment feature allows a separate router ID per VRF using a new keyword in the existing bgp router-id command. The router ID can be manually configured for each VRF or can be assigned automatically either globally under address family configuration mode or for each VRF.

Prerequisites for Per-VRF Assignment of BGP Router ID

Before you configure this feature, Cisco Express Forwarding or distributed Cisco Express Forwarding must be enabled in the network, and basic BGP peering is assumed to be running in the network.

Information About Per-VRF Assignment of BGP Router ID

BGP Router ID

The BGP router identifier (ID) is a 4-byte field that is set to the highest IP address on the router. Loopback interface addresses are considered before physical interface addresses because loopback interfaces are more stable than physical interfaces. The BGP router ID is used in the BGP algorithm for determining the best path to a destination where the preference is for the BGP router with the lowest router ID. It is possible to manually configure the BGP router ID using the bgp router-id command to influence the best path algorithm.

Per-VRF Router ID Assignment

In Cisco IOS XE Release 2.1 and later releases, support for configuring separate router IDs for each Virtual Private Network (VPN) routing/forwarding (VRF) instance was introduced. The Per-VRF Assignment of BGP Router ID feature introduces the ability to have VRF-to-VRF peering in Border Gateway Protocol (BGP) on the same router. BGP is designed to refuse a session with itself because of the router ID check. The per-VRF assignment feature allows a separate router ID per VRF using a new keyword in the existing bgp router-id command. The router ID can be manually configured for each VRF or can be assigned automatically either globally under address family configuration mode or for each VRF.

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

How to Configure Per-VRF Assignment of BGP Router ID

Configuring VRF Instances

Perform this task to configure VRF instances to be used with the per-VRF assignment tasks. In this task, a VRF instance named vrf_trans is created. To make the VRF functional, a route distinguisher is created. When the route distinguisher is created, the routing and forwarding tables are created for the VRF instance named vrf_trans.

Before you begin

This task assumes that you have Cisco Express Forwarding or distributed Cisco Express Forwarding enabled.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. ip vrf vrf-name
  4. rd route-distinguisher
  5. route-target {import | both } route-target-ext-community
  6. route-target {export | both } route-target-ext-community
  7. exit
  8. Repeat Step 3 through Step 7 for each VRF to be defined.

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

ip vrf vrf-name

Example:


Router(config)# ip vrf vrf_trans

Defines a VRF instance and enters VRF configuration mode.

Step 4

rd route-distinguisher

Example:


Router(config-vrf)# rd 45000:2

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 you can use to specify an RD. For more details, see the "Route Distinguisher" section.

  • In this example, the RD uses an autonomous system number with the number 2 after the colon.

Step 5

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

Example:


Router(config-vrf)# route-target import 55000:5

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 6

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

Example:


Router(config-vrf)# route-target export 55000:1

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.

Step 7

exit

Example:


Router(config-vrf)# exit

Exits VRF configuration mode and returns to global configuration mode.

Step 8

Repeat Step 3 through Step 7 for each VRF to be defined.

--

Associating VRF Instances with Interfaces

Perform this task to associate VRF instances with interfaces to be used with the per-VRF assignment tasks. In this task, a VRF instance named vrf_trans is associated with a serial interface.

Make a note of the IP addresses for any interface to which you want to associate a VRF instance because the ip vrf forwarding command removes the IP address. Step 8 allows you to reconfigure the IP address.

Before you begin

  • This task assumes that you have Cisco Express Forwarding or distributed Cisco Express Forwarding enabled.

  • This task assumes that VRF instances have been configured in the Configuring VRF Instances.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ip address ip-address mask [secondary ]
  5. exit
  6. interface type number
  7. ip vrf forwarding vrf-name [downstream vrf-name2 ]
  8. ip address ip-address mask [secondary ]
  9. Repeat Step 5 through Step 8 for each VRF to be associated with an interface.
  10. end
  11. show ip vrf [brief | detail | interfaces | id ] [vrf-name ]

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

interface type number

Example:


Router(config)# interface loopback0

Configures an interface type and enters interface configuration mode.

  • In this example, loopback interface 0 is configured.

Step 4

ip address ip-address mask [secondary ]

Example:


Router(config-if)# ip address 172.16.1.1 255.255.255.255

Configures an IP address.

  • In this example, the loopback interface is configured with an IP address of 172.16.1.1.

Step 5

exit

Example:


Router(config-if)# exit

Exits interface configuration mode and returns to global configuration mode.

Step 6

interface type number

Example:


Router(config)# interface serial2/0/0

Configures an interface type and enters interface configuration mode.

  • In this example, serial interface 2/0/0 is configured.

Step 7

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

Example:


Router(config-if)# ip vrf forwarding vrf_trans

Associates a VRF with an interface or subinterface.

  • In this example, the VRF named vrf_trans is associated with serial interface 2/0/0.

Note

 

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

Step 8

ip address ip-address mask [secondary ]

Example:


Router(config-if)# ip address 192.168.4.1 255.255.255.0

Configures an IP address.

  • In this example, serial interface 2/0/0 is configured with an IP address of 192.168.4.1.

Step 9

Repeat Step 5 through Step 8 for each VRF to be associated with an interface.

--

Step 10

end

Example:


Router(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Step 11

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

Example:


Router# show ip vrf interfaces

(Optional) Displays the set of defined VRFs and associated interfaces.

  • In this example, the output from this command shows the VRFs that have been created and their associated interfaces.

Examples

The following output shows that two VRF instances named vrf_trans and vrf_users were configured on two serial interfaces. 


Router# show ip vrf interfaces
Interface         IP-Address      VRF                      Protocol
Serial2           192.168.4.1     vrf_trans                up      
Serial3           192.168.5.1     vrf_user                 up

Manually Configuring a BGP Router ID per VRF

Perform this task to manually configure a BGP router ID for each VRF. In this task, several address family configurations are shown and the router ID is configured in the IPv4 address family mode for one VRF instance. Step 22 shows you how to repeat certain steps to permit the configuration of more than one VRF on the same router.

Before you begin

This task assumes that you have previously created the VRF instances and associated them with interfaces. For more details, see the Configuring VRF Instances and the Associating VRF Instances with Interfaces.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. router bgp autonomous-system-number
  4. no bgp default ipv4-unicast
  5. bgp log-neighbor-changes
  6. neighbor {ip-address | peer-group-name } remote-as autonomous-system-number
  7. neighbor {ip-address | peer-group-name } update-source interface-type interface-number
  8. address-family {ipv4 [mdt | multicast | unicast [vrf vrf-name ] | vrf vrf-name ] | vpnv4 [unicast ]}
  9. neighbor {ip-address | peer-group-name } activate
  10. neighbor {ip-address | peer-group-name } send-community {both | standard | extended }
  11. exit-address-family
  12. address-family {ipv4 [mdt | multicast | unicast [vrf vrf-name ] | vrf vrf-name ] | vpnv4 [unicast ]}
  13. redistribute connected
  14. neighbor {ip-address | peer-group-name } remote-as autonomous-system-number
  15. neighbor ip-address local-as autonomous-system-number [no-prepend [replace-as [dual-as ]]]
  16. neighbor {ip-address | peer-group-name } ebgp-multihop [ttl ]
  17. neighbor {ip-address | peer-group-name } activate
  18. neighbor ip-address allowas-in [number ]
  19. no auto-summary
  20. no synchronization
  21. bgp router-id {ip-address | auto-assign }
  22. Repeat Step 11 to Step 21 to configure another VRF instance.
  23. end
  24. show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name }

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 45000

Enters router configuration mode for the specified routing process.

Step 4

no bgp default ipv4-unicast

Example:


Router(config-router)# no bgp default ipv4-unicast

Disables the IPv4 unicast address family for the BGP routing process.

Note

 

Routing information for the IPv4 unicast address family is advertised by default for each BGP routing session configured with the neighbor remote-as router configuration command unless you configure the no bgp default ipv4-unicast router configuration command before configuring the neighbor remote-as command. Existing neighbor configurations are not affected.

Step 5

bgp log-neighbor-changes

Example:


Router(config-router)# bgp log-neighbor-changes

Enables logging of BGP neighbor resets.

Step 6

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

Example:


Router(config-router)# neighbor 192.168.1.1 remote-as 45000

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

  • If the autonomous-system-number argument matches the autonomous system number specified in the router bgp command, the neighbor is an internal neighbor.

  • If the autonomous-system-number argument does not match the autonomous system number specified in the router bgp command, the neighbor is an external neighbor.

  • In this example, the neighbor is an internal neighbor.

Step 7

neighbor {ip-address | peer-group-name } update-source interface-type interface-number

Example:


Router(config-router)# neighbor 192.168.1.1 update-source loopback0

Allows BGP sessions to use any operational interface for TCP connections.

  • In this example, BGP TCP connections for the specified neighbor are sourced with the IP address of the loopback interface rather than the best local address.

Step 8

address-family {ipv4 [mdt | multicast | unicast [vrf vrf-name ] | vrf vrf-name ] | vpnv4 [unicast ]}

Example:


Router(config-router)# address-family vpnv4

Enters address family configuration mode to configure BGP peers to accept address-family-specific configurations.

  • The example creates a VPNv4 address family session.

Step 9

neighbor {ip-address | peer-group-name } activate

Example:


Router(config-router-af)# neighbor 172.16.1.1 activate

Activates the neighbor under the VPNv4 address family.

  • In this example, the neighbor 172.16.1.1 is activated.

Step 10

neighbor {ip-address | peer-group-name } send-community {both | standard | extended }

Example:


Router(config-router-af)# neighbor 172.16.1.1 send-community extended

Specifies that a communities attribute should be sent to a BGP neighbor.

  • In this example, an extended communities attribute is sent to the neighbor at 172.16.1.1.

Step 11

exit-address-family

Example:


Router(config-router-af)# exit-address-family

Exits address family configuration mode and returns to router configuration mode.

Step 12

address-family {ipv4 [mdt | multicast | unicast [vrf vrf-name ] | vrf vrf-name ] | vpnv4 [unicast ]}

Example:


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

Enters address family configuration mode to configure BGP peers to accept address-family-specific configurations.

  • The example specifies that the VRF instance named vrf_trans is to be associated with subsequent IPv4 address family configuration commands.

Step 13

redistribute connected

Example:


Router(config-router-af)# redistribute connected

Redistributes from one routing domain into another routing domain.

  • In this example, the connected keyword is used to represent routes that are established automatically when IP is enabled on an interface.

  • Only the syntax applicable to this step is displayed. For more details, see the Cisco IOS IP Routing: BGP Command Reference.

Step 14

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

Example:


Router(config-router-af)# neighbor 192.168.1.1 remote-as 40000

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

  • If the autonomous-system-number argument matches the autonomous system number specified in the router bgp command, the neighbor is an internal neighbor.

  • If the autonomous-system-number argument does not match the autonomous system number specified in the router bgp command, the neighbor is an external neighbor.

  • In this example, the neighbor at 192.168.1.1 is an external neighbor.

Step 15

neighbor ip-address local-as autonomous-system-number [no-prepend [replace-as [dual-as ]]]

Example:


Router(config-router-af)# neighbor 192.168.1.1 local-as 50000 no-prepend

Customizes the AS_PATH attribute for routes received from an eBGP neighbor.

  • The autonomous system number from the local BGP routing process is prepended to all external routes by default.

  • Use the no-prepend keyword to not prepend the local autonomous system number to any routes received from the eBGP neighbor.

  • In this example, routes from the neighbor at 192.168.1.1 will not contain the local autonomous system number.

Step 16

neighbor {ip-address | peer-group-name } ebgp-multihop [ttl ]

Example:


Router(config-router-af)# neighbor 192.168.1.1 ebgp-multihop 2

Accepts and attempts BGP connections to external peers residing on networks that are not directly connected.

  • In this example, BGP is configured to allow connections to or from neighbor 192.168.1.1, which resides on a network that is not directly connected.

Step 17

neighbor {ip-address | peer-group-name } activate

Example:


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

Activates the neighbor under the IPV4 address family.

  • In this example, the neighbor 192.168.1.1 is activated.

Step 18

neighbor ip-address allowas-in [number ]

Example:


Router(config-router-af)# neighbor 192.168.1.1 allowas-in 1

Configures provider edge (PE) routers to allow the readvertisement of all prefixes that contain duplicate autonomous system numbers.

  • In the example, the PE router with autonomous system number 45000 is configured to allow prefixes from the VRF vrf-trans. The neighboring PE router with the IP address 192.168.1.1 is set to be readvertised once to other PE routers with the same autonomous system number.

Step 19

no auto-summary

Example:


Router(config-router-af)# no auto-summary

Disables automatic summarization and sends subprefix routing information across classful network boundaries.

Step 20

no synchronization

Example:


Router(config-router-af)# no synchronization

Enables the Cisco IOS XE software to advertise a network route without waiting for synchronization with an Internal Gateway Protocol (IGP).

Step 21

bgp router-id {ip-address | auto-assign }

Example:


Router(config-router-af)# bgp router-id 10.99.1.1

Configures a fixed router ID for the local BGP routing process.

  • In this example, the specified BGP router ID is assigned for the VRF instance associated with this IPv4 address family configuration.

Step 22

Repeat Step 11 to Step 21 to configure another VRF instance.

--

Step 23

end

Example:


Router(config-router-af)# end

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

Step 24

show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name }

Example:


Router# show ip bgp vpnv4 all

(Optional) Displays VPN address information from the BGP table.

  • In this example, the complete VPNv4 database is displayed.

Note

 

Only the syntax applicable to this task is used in this example. For more details, see the Cisco IOS Multiprotocol Label Switching Command Reference.

Examples

The following sample output assumes that two VRF instances named vrf_trans and vrf_user were configured each with a separate router ID. The router ID is shown next to the VRF name. 


Router# show ip bgp vpnv4 all
BGP table version is 5, local router ID is 172.17.1.99
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 1:1 (default for vrf vrf_trans) VRF Router ID 10.99.1.2
*> 192.168.4.0      0.0.0.0                  0         32768 ?
Route Distinguisher: 42:1 (default for vrf vrf_user) VRF Router ID 10.99.1.1
*> 192.168.5.0      0.0.0.0                  0         32768 ?

Automatically Assigning a BGP Router ID per VRF

Perform this task to automatically assign a BGP router ID for each VRF. In this task, a loopback interface is associated with a VRF and the bgp router-id command is configured at the router configuration level to automatically assign a BGP router ID to all VRF instances. Step 9 shows you how to repeat certain steps to configure each VRF that is to be associated with an interface. Step 30 shows you how to configure more than one VRF on the same router.

Before you begin

This task assumes that you have previously created the VRF instances. For more details, see the Configuring VRF Instances.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ip address ip-address mask [secondary ]
  5. exit
  6. interface type number
  7. ip vrf forwarding vrf-name [downstream vrf-name2 ]
  8. ip address ip-address mask [secondary ]
  9. Repeat Step 5 through Step 8 for each VRF to be associated with an interface.
  10. exit
  11. router bgp autonomous-system-number
  12. bgp router-id {ip-address | vrf auto-assign }
  13. no bgp default ipv4-unicast
  14. bgp log-neighbor-changes
  15. neighbor {ip-address | peer-group-name } remote-as autonomous-system-number
  16. neighbor {ip-address | peer-group-name } update-source interface-type interface-number
  17. address-family {ipv4 [mdt | multicast | unicast [vrf vrf-name ] | vrf vrf-name ] | vpnv4 [unicast ]}
  18. neighbor {ip-address | peer-group-name } activate
  19. neighbor {ip-address | peer-group-name } send-community {both | standard | extended }
  20. exit-address-family
  21. address-family {ipv4 [mdt | multicast | unicast [vrf vrf-name ] | vrf vrf-name ] | vpnv4 [unicast ]}
  22. redistribute connected
  23. neighbor {ip-address | peer-group-name } remote-as autonomous-system-number
  24. neighbor ip-address local-as autonomous-system-number [no-prepend [replace-as [dual-as ]]]
  25. neighbor {ip-address | peer-group-name } ebgp-multihop [ttl ]
  26. neighbor {ip-address | peer-group-name } activate
  27. neighbor ip-address allowas-in [number ]
  28. no auto-summary
  29. no synchronization
  30. Repeat Step 20 to Step 29 to configure another VRF instance.
  31. end
  32. show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name }

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

interface type number

Example:


Router(config)# interface loopback0

Configures an interface type and enters interface configuration mode.

  • In this example, loopback interface 0 is configured.

Step 4

ip address ip-address mask [secondary ]

Example:


Router(config-if)# ip address 172.16.1.1 255.255.255.255

Configures an IP address.

  • In this example, the loopback interface is configured with an IP address of 172.16.1.1.

Step 5

exit

Example:


Router(config-if)# exit

Exits interface configuration mode and returns to global configuration mode.

Step 6

interface type number

Example:


Router(config)# interface loopback1

Configures an interface type and enters interface configuration mode.

  • In this example, loopback interface 1 is configured.

Step 7

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

Example:


Router(config-if)# ip vrf forwarding vrf_trans

Associates a VRF with an interface or subinterface.

  • In this example, the VRF named vrf_trans is associated with loopback interface 1.

Note

 

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

Step 8

ip address ip-address mask [secondary ]

Example:


Router(config-if)# ip address 10.99.1.1 255.255.255.255

Configures an IP address.

  • In this example, loopback interface 1 is configured with an IP address of 10.99.1.1.

Step 9

Repeat Step 5 through Step 8 for each VRF to be associated with an interface.

--

Step 10

exit

Example:


Router(config-if)# exit

Exits interface configuration mode and returns to global configuration mode.

Step 11

router bgp autonomous-system-number

Example:


Router(config)# router bgp 45000

Enters router configuration mode for the specified routing process.

Step 12

bgp router-id {ip-address | vrf auto-assign }

Example:


Router(config-router)# bgp router-id vrf auto-assign

Configures a fixed router ID for the local BGP routing process.

  • In this example, a BGP router ID is automatically assigned for each VRF instance.

Step 13

no bgp default ipv4-unicast

Example:


Router(config-router)# no bgp default ipv4-unicast

Disables the IPv4 unicast address family for the BGP routing process.

Note

 

Routing information for the IPv4 unicast address family is advertised by default for each BGP routing session configured with the neighbor remote-as router configuration command unless you configure the no bgp default ipv4-unicast router configuration command before configuring the neighbor remote-as command. Existing neighbor configurations are not affected.

Step 14

bgp log-neighbor-changes

Example:


Router(config-router)# bgp log-neighbor-changes

Enables logging of BGP neighbor resets.

Step 15

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

Example:


Router(config-router)# neighbor 192.168.1.1 remote-as 45000

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

  • If the autonomous-system-number argument matches the autonomous system number specified in the router bgp command, the neighbor is an internal neighbor.

  • If the autonomous-system-number argument does not match the autonomous system number specified in the router bgp command, the neighbor is an external neighbor.

  • In this example, the neighbor is an internal neighbor.

Step 16

neighbor {ip-address | peer-group-name } update-source interface-type interface-number

Example:


Router(config-router)# neighbor 192.168.1.1 update-source loopback0

Allows BGP sessions to use any operational interface for TCP connections.

  • In this example, BGP TCP connections for the specified neighbor are sourced with the IP address of the loopback interface rather than the best local address.

Step 17

address-family {ipv4 [mdt | multicast | unicast [vrf vrf-name ] | vrf vrf-name ] | vpnv4 [unicast ]}

Example:


Router(config-router)# address-family vpnv4

Enters address family configuration mode to configure BGP peers to accept address-family-specific configurations.

  • The example creates a VPNv4 address family session.

Step 18

neighbor {ip-address | peer-group-name } activate

Example:


Router(config-router-af)# neighbor 172.16.1.1 activate

Activates the neighbor under the VPNv4 address family.

  • In this example, the neighbor 172.16.1.1 is activated.

Step 19

neighbor {ip-address | peer-group-name } send-community {both | standard | extended }

Example:


Router(config-router-af)# neighbor 172.16.1.1 send-community extended

Specifies that a communities attribute should be sent to a BGP neighbor.

  • In this example, an extended communities attribute is sent to the neighbor at 172.16.1.1.

Step 20

exit-address-family

Example:


Router(config-router-af)# exit-address-family

Exits address family configuration mode and returns to router configuration mode.

Step 21

address-family {ipv4 [mdt | multicast | unicast [vrf vrf-name ] | vrf vrf-name ] | vpnv4 [unicast ]}

Example:


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

Enters address family configuration mode to configure BGP peers to accept address-family-specific configurations.

  • The example specifies that the VRF instance named vrf_trans is to be associated with subsequent IPv4 address family configuration mode commands.

Step 22

redistribute connected

Example:


Router(config-router-af)# redistribute connected

Redistributes from one routing domain into another routing domain.

  • In this example, the connected keyword is used to represent routes that are established automatically when IP is enabled on an interface.

  • Only the syntax applicable to this step is displayed. For more details, see the Cisco IOS IP Routing: BGP Command Reference.

Step 23

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

Example:


Router(config-router-af)# neighbor 192.168.1.1 remote-as 40000

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

  • If the autonomous-system-number argument matches the autonomous system number specified in the router bgp command, the neighbor is an internal neighbor.

  • If the autonomous-system-number argument does not match the autonomous system number specified in the router bgp command, the neighbor is an external neighbor.

  • In this example, the neighbor at 192.168.1.1 is an external neighbor.

Step 24

neighbor ip-address local-as autonomous-system-number [no-prepend [replace-as [dual-as ]]]

Example:


Router(config-router-af)# neighbor 192.168.1.1 local-as 50000 no-prepend

Customizes the AS_PATH attribute for routes received from an eBGP neighbor.

  • The autonomous system number from the local BGP routing process is prepended to all external routes by default.

  • Use the no-prepend keyword to not prepend the local autonomous system number to any routes received from the eBGP neighbor.

  • In this example, routes from the neighbor at 192.168.1.1 will not contain the local autonomous system number.

Step 25

neighbor {ip-address | peer-group-name } ebgp-multihop [ttl ]

Example:


Router(config-router-af)# neighbor 192.168.1.1 ebgp-multihop 2

Accepts and attempts BGP connections to external peers residing on networks that are not directly connected.

  • In this example, BGP is configured to allow connections to or from neighbor 192.168.1.1, which resides on a network that is not directly connected.

Step 26

neighbor {ip-address | peer-group-name } activate

Example:


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

Activates the neighbor under the IPV4 address family.

  • In this example, the neighbor 192.168.1.1 is activated.

Step 27

neighbor ip-address allowas-in [number ]

Example:


Router(config-router-af)# neighbor 192.168.1.1 allowas-in 1

Configures provider edge (PE) routers to allow the readvertisement of all prefixes that contain duplicate autonomous system numbers.

  • In the example, the PE router with autonomous system number 45000 is configured to allow prefixes from the VRF vrf-trans. The neighboring PE router with the IP address 192.168.1.1 is set to be readvertised once to other PE routers with the same autonomous system number.

Step 28

no auto-summary

Example:


Router(config-router-af)# no auto-summary

Disables automatic summarization and sends subprefix routing information across classful network boundaries.

Step 29

no synchronization

Example:


Router(config-router-af)# no synchronization

Enables the Cisco IOS XE software to advertise a network route without waiting for synchronization with an Internal Gateway Protocol (IGP).

Step 30

Repeat Step 20 to Step 29 to configure another VRF instance.

--

Step 31

end

Example:


Router(config-router-af)# end

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

Step 32

show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name }

Example:


Router# show ip bgp vpnv4 all

(Optional) Displays VPN address information from the BGP table.

  • In this example, the complete VPNv4 database is displayed.

Note

 

Only the syntax applicable to this task is used in this example. For more details, see the Cisco IOS Multiprotocol Label Switching Command Reference.

Examples

The following sample output assumes that two VRF instances named vrf_trans and vrf_user were configured, each with a separate router ID. The router ID is shown next to the VRF name. 


Router# show ip bgp vpnv4 all
BGP table version is 43, local router ID is 172.16.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 1:1 (default for vrf vrf_trans) VRF Router ID 10.99.1.2
*> 172.22.0.0       0.0.0.0                  0         32768 ?
r> 172.23.0.0       172.23.1.1               0             0 3 1 ?
*>i10.21.1.1/32     192.168.3.1              0    100      0 2 i
*> 10.52.1.0/24     172.23.1.1                             0 3 1 ?
*> 10.52.2.1/32     172.23.1.1                             0 3 1 3 i
*> 10.52.3.1/32     172.23.1.1                             0 3 1 3 i
*> 10.99.1.1/32     172.23.1.1               0             0 3 1 ?
*> 10.99.1.2/32     0.0.0.0                  0         32768 ?
Route Distinguisher: 10:1
*>i10.21.1.1/32     192.168.3.1              0    100      0 2 i
Route Distinguisher: 42:1 (default for vrf vrf_user) VRF Router ID 10.99.1.1
r> 172.22.0.0       172.22.1.1               0             0 2 1 ?
*> 172.23.0.0       0.0.0.0                  0         32768 ?
*> 10.21.1.1/32     172.22.1.1                             0 2 1 2 i
*>i10.52.1.0/24     192.168.3.1              0    100      0 ?
*>i10.52.2.1/32     192.168.3.1              0    100      0 3 i
*>i10.52.3.1/32     192.168.3.1              0    100      0 3 i
*> 10.99.1.1/32     0.0.0.0                  0         32768 ?
*> 10.99.1.2/32     172.22.1.1               0             0 2 1 ?

Configuration Examples for Per-VRF Assignment of BGP Router ID

Manually Configuring a BGP Router ID per VRF Examples

The following example shows how to configure two VRFs--vrf_trans and vrf_user--with sessions between each other on the same router. The BGP router ID for each VRF is configured manually under separate IPv4 address families. The show ip bgp vpnv4 command can be used to verify that the router IDs have been configured for each VRF. The configuration starts in global configuration mode. 


ip vrf vrf_trans
 rd 45000:1
 route-target export 50000:50
 route-target import 40000:1
!
ip vrf vrf_user
 rd 65500:1
 route-target export 65500:1
 route-target import 65500:1
!
interface Loopback0
 ip address 10.1.1.1 255.255.255.255
!
router bgp 45000
 no bgp default ipv4-unicast
 bgp log-neighbor-changes
 neighbor 192.168.3.1 remote-as 45000
 neighbor 192.168.3.1 update-source Loopback0
 !
 address-family vpnv4
  neighbor 192.168.3.1 activate
  neighbor 192.168.3.1 send-community extended
  exit-address-family
 !
 address-family ipv4 vrf vrf_user
  redistribute connected
  neighbor 172.22.1.1 remote-as 40000
  neighbor 172.22.1.1 local-as 50000 no-prepend
  neighbor 172.22.1.1 ebgp-multihop 2
  neighbor 172.22.1.1 activate
  neighbor 172.22.1.1 allowas-in 1
  no auto-summary
  no synchronization
  bgp router-id 10.99.1.1
  exit-address-family
 !
 address-family ipv4 vrf vrf_trans
  redistribute connected
  neighbor 172.23.1.1 remote-as 50000
  neighbor 172.23.1.1 local-as 40000 no-prepend
  neighbor 172.23.1.1 ebgp-multihop 2
  neighbor 172.23.1.1 activate
  neighbor 172.23.1.1 allowas-in 1
  no auto-summary
  no synchronization
  bgp router-id 10.99.1.2
  exit-address-family

After the configuration, the output of the show ip bgp vpnv4 all command shows the router ID displayed next to the VRF name: 


Router# show ip bgp vpnv4 all
BGP table version is 43, local router ID is 10.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 45000:1 (default for vrf vrf_trans) VRF Router ID 10.99.1.2
*> 172.22.0.0       0.0.0.0                  0         32768 ?
r> 172.23.0.0       172.23.1.1               0             0 3 1 ?
*>i10.21.1.1/32     192.168.3.1              0    100      0 2 i
*> 10.52.1.0/24     172.23.1.1                             0 3 1 ?
*> 10.52.2.1/32     172.23.1.1                             0 3 1 3 i
*> 10.52.3.1/32     172.23.1.1                             0 3 1 3 i
*> 10.99.1.1/32     172.23.1.1               0             0 3 1 ?
*> 10.99.2.2/32     0.0.0.0                  0         32768 ?
Route Distinguisher: 50000:1
*>i10.21.1.1/32     192.168.3.1              0    100      0 2 i
Route Distinguisher: 65500:1 (default for vrf vrf_user) VRF Router ID 10.99.1.1
r> 172.22.0.0       172.22.1.1               0             0 2 1 ?
*> 172.23.0.0       0.0.0.0                  0         32768 ?
*> 10.21.1.1/32     172.22.1.1                             0 2 1 2 i
*>i10.52.1.0/24     192.168.3.1              0    100      0 ?
*>i10.52.2.1/32     192.168.3.1              0    100      0 3 i
*>i10.52.3.1/32     192.168.3.1              0    100      0 3 i
*> 10.99.1.1/32     0.0.0.0                  0         32768 ?
*> 10.99.2.2/32     172.22.1.1               0             0 2 1 ?

The output of the show ip bgp vpnv4 vrf command for a specified VRF displays the router ID in the output header: 


Router# show ip bgp vpnv4 vrf vrf_user
BGP table version is 43, local router ID is 10.99.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 65500:1 (default for vrf vrf_user) VRF Router ID 10.99.1.1
r> 172.22.0.0       172.22.1.1               0             0 2 1 ?
*> 172.23.0.0       0.0.0.0                  0         32768 ?
*> 10.21.1.1/32     172.22.1.1                             0 2 1 2 i
*>i10.52.1.0/24     192.168.3.1              0    100      0 ?
*>i10.52.2.1/32     192.168.3.1              0    100      0 3 i
*>i10.52.3.1/32     192.168.3.1              0    100      0 3 i
*> 10.99.1.1/32     0.0.0.0                  0         32768 ?
*> 10.99.2.2/32     172.22.1.1               0             0 2 1 ?

The output of the show ip bgp vpnv4 vrf summary command for a specified VRF displays the router ID in the first line of the output: 


Router# show ip bgp vpnv4 vrf vrf_user summary
BGP router identifier 10.99.1.1, local AS number 45000
BGP table version is 43, main routing table version 43
8 network entries using 1128 bytes of memory
8 path entries using 544 bytes of memory
16/10 BGP path/bestpath attribute entries using 1856 bytes of memory
6 BGP AS-PATH entries using 144 bytes of memory
3 BGP extended community entries using 72 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 3744 total bytes of memory
BGP activity 17/0 prefixes, 17/0 paths, scan interval 15 secs
Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
172.22.1.1      4     2      20      21       43    0    0 00:12:33        3

When the path is sourced in the VRF, the correct router ID is displayed in the output of the show ip bgp vpnv4 vrf command for a specified VRF and network address: 


Router# show ip bgp vpnv4 vrf vrf_user 172.23.0.0
BGP routing table entry for 65500:1:172.23.0.0/8, version 22
Paths: (1 available, best #1, table vrf_user)
  Advertised to update-groups:
     2          3         
  Local
    0.0.0.0 from 0.0.0.0 (10.99.1.1)
      Origin incomplete, metric 0, localpref 100, weight 32768, valid, sourced, best
      Extended Community: RT:65500:1

Automatically Assigning a BGP Router ID per VRF Examples

The following three configuration examples show different methods of configuring BGP to automatically assign a separate router ID to each VRF instance:

Globally Automatically Assigned Router ID Using Loopback Interface IP Addresses Example

The following example shows how to configure two VRFs--vrf_trans and vrf_user--with sessions between each other on the same router. Under router configuration mode, BGP is globally configured to automatically assign each VRF a BGP router ID. Loopback interfaces are associated with individual VRFs to source an IP address for the router ID. The show ip bgp vpnv4 command can be used to verify that the router IDs have been configured for each VRF. 


ip vrf vrf_trans
 rd 45000:1
 route-target export 50000:50
 route-target import 40000:1
!
ip vrf vrf_user
 rd 65500:1
 route-target export 65500:1
 route-target import 65500:1
!
interface Loopback0
 ip address 10.1.1.1 255.255.255.255
!
interface Loopback1
 ip vrf forwarding vrf_user
 ip address 10.99.1.1 255.255.255.255
!
interface Loopback2
 ip vrf forwarding vrf_trans
 ip address 10.99.2.2 255.255.255.255
!
router bgp 45000
 bgp router-id vrf auto-assign
 no bgp default ipv4-unicast
 bgp log-neighbor-changes
 neighbor 192.168.3.1 remote-as 45000
 neighbor 192.168.3.1 update-source Loopback0
 !
address-family vpnv4
  neighbor 192.168.3.1 activate
  neighbor 192.168.3.1 send-community extended
  exit-address-family
 !
 address-family ipv4 vrf vrf_user
  redistribute connected
  neighbor 172.22.1.1 remote-as 40000
  neighbor 172.22.1.1 local-as 50000 no-prepend
  neighbor 172.22.1.1 ebgp-multihop 2
  neighbor 172.22.1.1 activate
  neighbor 172.22.1.1 allowas-in 1
  no auto-summary
  no synchronization
  exit-address-family
 !
 address-family ipv4 vrf vrf_trans
  redistribute connected
  neighbor 172.23.1.1 remote-as 50000
  neighbor 172.23.1.1 local-as 2 no-prepend
  neighbor 172.23.1.1 ebgp-multihop 2
  neighbor 172.23.1.1 activate
  neighbor 172.23.1.1 allowas-in 1
  no auto-summary
  no synchronization
  exit-address-family

After the configuration, the output of the show ip bgp vpnv4 all command shows the router ID displayed next to the VRF name. Note that the router IDs used in this example are sourced from the IP addresses configured for loopback interface 1 and loopback interface 2. The router IDs are the same as in the Manually Configuring a BGP Router ID per VRF Examples. 


Router# show ip bgp vpnv4 all
BGP table version is 43, local router ID is 10.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 45000:1 (default for vrf vrf_trans) VRF Router ID 10.99.2.2
*> 172.22.0.0       0.0.0.0                  0         32768 ?
r> 172.23.0.0       172.23.1.1               0             0 3 1 ?
*>i10.21.1.1/32     192.168.3.1              0    100      0 2 i
*> 10.52.1.0/24     172.23.1.1                             0 3 1 ?
*> 10.52.2.1/32     172.23.1.1                             0 3 1 3 i
*> 10.52.3.1/32     172.23.1.1                             0 3 1 3 i
*> 10.99.1.1/32     172.23.1.1               0             0 3 1 ?
*> 10.99.1.2/32     0.0.0.0                  0         32768 ?
Route Distinguisher: 50000:1
*>i10.21.1.1/32     192.168.3.1              0    100      0 2 i
Route Distinguisher: 65500:1 (default for vrf vrf_user) VRF Router ID 10.99.1.1
r> 172.22.0.0       172.22.1.1               0             0 2 1 ?
*> 172.23.0.0       0.0.0.0                  0         32768 ?
*> 10.21.1.1/32     172.22.1.1                             0 2 1 2 i
*>i10.52.1.0/24     192.168.3.1              0    100      0 ?
*>i10.52.2.1/32     192.168.3.1              0    100      0 3 i
*>i10.52.3.1/32     192.168.3.1              0    100      0 3 i
*> 10.99.1.1/32     0.0.0.0                  0         32768 ?
*> 10.99.1.2/32     172.22.1.1               0             0 2 1 ?

Globally Automatically Assigned Router ID with No Default Router ID Example

The following example shows how to configure a router and associate a VRF that is automatically assigned a BGP router ID when no default router ID is allocated. 


ip vrf vpn1
 rd 45000:1
 route-target export 45000:1
 route-target import 45000:1
!
interface Loopback0
 ip vrf forwarding vpn1
 ip address 10.1.1.1 255.255.255.255
!
router bgp 45000
 bgp router-id vrf auto-assign
 no bgp default ipv4-unicast
 bgp log-neighbor-changes
 !
 address-family ipv4 vrf vpn1
  neighbor 172.22.1.2 remote-as 40000
  neighbor 172.22.1.2 activate
  no auto-summary
  no synchronization
  exit-address-family

Assuming that a second router is configured to establish a session between the two routers, the output of the show ip interface brief command shows only the VRF interfaces that are configured. 


Router# show ip interface brief
Interface              IP-Address      OK? Method Status                Protocol
Serial2/0/0            unassigned      YES NVRAM  administratively down down    
Serial3/0/0            unassigned      YES NVRAM  administratively down down    
Loopback0              10.1.1.1        YES NVRAM  up                    up

The show ip vrf command can be used to verify that a router ID is assigned for the VRF: 


Router# show ip vrf
Name                             Default RD          Interfaces
  vpn1                             45000:1           Loopback0
VRF session is established:

Per-VRF Automatically Assigned Router ID Example

The following example shows how to configure two VRFs--vrf_trans and vrf_user--with sessions between each other on the same router. Under the IPv4 address family associated with an individual VRF, BGP is configured to automatically assign a BGP router ID. Loopback interfaces are associated with individual VRFs to source an IP address for the router ID. The output of the show ip bgp vpnv4 command can be used to verify that the router IDs have been configured for each VRF. 


ip vrf vrf_trans
 rd 45000:1
 route-target export 50000:50
 route-target import 40000:1
!
ip vrf vrf_user
 rd 65500:1
 route-target export 65500:1
 route-target import 65500:1
!
interface Loopback0
 ip address 10.1.1.1 255.255.255.255
!
interface Loopback1
 ip vrf forwarding vrf_user
 ip address 10.99.1.1 255.255.255.255
!
interface Loopback2
 ip vrf forwarding vrf_trans
 ip address 10.99.2.2 255.255.255.255
!
router bgp 45000
 no bgp default ipv4-unicast
 bgp log-neighbor-changes
 neighbor 192.168.3.1 remote-as 45000
 neighbor 192.168.3.1 update-source Loopback0
 !
address-family vpnv4
  neighbor 192.168.3.1 activate
  neighbor 192.168.3.1 send-community extended
  exit-address-family
!
 address-family ipv4 vrf vrf_user
  redistribute connected
  neighbor 172.22.1.1 remote-as 40000
  neighbor 172.22.1.1 local-as 50000 no-prepend
  neighbor 172.22.1.1 ebgp-multihop 2
  neighbor 172.22.1.1 activate
  neighbor 172.22.1.1 allowas-in 1
  no auto-summary
  no synchronization
  bgp router-id auto-assign
  exit-address-family
 !
 address-family ipv4 vrf vrf_trans
  redistribute connected
  neighbor 172.23.1.1 remote-as 50000
  neighbor 172.23.1.1 local-as 40000 no-prepend
  neighbor 172.23.1.1 ebgp-multihop 2
  neighbor 172.23.1.1 activate
  neighbor 172.23.1.1 allowas-in 1
  no auto-summary
  no synchronization
  bgp router-id auto-assign
  exit-address-family

After the configuration, the output of the show ip bgp vpnv4 all command shows the router ID displayed next to the VRF name. Note that the router IDs used in this example are sourced from the IP addresses configured for loopback interface 1 and loopback interface 2. 


Router# show ip bgp vpnv4 all
BGP table version is 43, local router ID is 10.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 45000:1 (default for vrf vrf_trans) VRF Router ID 10.99.2.2
*> 172.22.0.0       0.0.0.0                  0         32768 ?
r> 172.23.0.0       172.23.1.1               0             0 3 1 ?
*>i10.21.1.1/32     192.168.3.1              0    100      0 2 i
*> 10.52.1.0/24     172.23.1.1                             0 3 1 ?
*> 10.52.2.1/32     172.23.1.1                             0 3 1 3 i
*> 10.52.3.1/32     172.23.1.1                             0 3 1 3 i
*> 10.99.1.1/32     172.23.1.1               0             0 3 1 ?
*> 10.99.1.2/32     0.0.0.0                  0         32768 ?
Route Distinguisher: 50000:1
*>i10.21.1.1/32     192.168.3.1              0    100      0 2 i
Route Distinguisher: 65500:1 (default for vrf vrf_user) VRF Router ID 10.99.1.1
r> 172.22.0.0       172.22.1.1               0             0 2 1 ?
*> 172.23.0.0       0.0.0.0                  0         32768 ?
*> 10.21.1.1/32     172.22.1.1                             0 2 1 2 i
*>i10.52.1.0/24     192.168.3.1              0    100      0 ?
*>i10.52.2.1/32     192.168.3.1              0    100      0 3 i
*>i10.52.3.1/32     192.168.3.1              0    100      0 3 i
*> 10.99.1.1/32     0.0.0.0                  0         32768 ?
*> 10.99.1.2/32     172.22.1.1               0             0 2 1 ?

Additional References

Related Documents

Related Topic

Document Title

BGP commands: complete command syntax, defaults, command mode, command history, usage guidelines, and examples

Cisco IOS IP Routing: BGP Command Reference

MPLS commands: complete command syntax, defaults, command mode, command history, usage guidelines, and examples

Cisco IOS Multiprotocol Label Switching Command Reference

Cisco IOS master command list, all releases

Cisco IOS Master Command List, All Releases

Standards

Standard

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIB

MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

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

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

RFCs

RFC

Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

--

Technical Assistance

Description

Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport

Feature Information for Per-VRF Assignment of BGP Router ID

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 Per-VRF Assignment of BGP Router ID

Feature Name

Releases

Feature Information

Per-VRF Assignment of BGP Router ID

Cisco IOS XE Release 2.1

The Per-VRF Assignment of BGP Router ID feature introduces the ability to have VRF-to-VRF peering in Border Gateway Protocol (BGP) on the same router. BGP is designed to refuse a session with itself because of the router ID check. The per-VRF assignment feature allows a separate router ID per VRF using a new keyword in the existing bgp router-id command. The router ID can be manually configured for each VRF or can be assigned automatically either globally under address family configuration mode or for each VRF.

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

The following commands were introduced or modified by this feature: bgp router-id , show ip bgp vpnv4 .