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Table Of Contents
BGP Multicast Inter-AS (IAS) VPN
How to Configure an MDT Address Family Session in BGP
Configuring the MDT Address Family in BGP
Clearing IPv4 MDT Peering Sessions in BGP
Displaying Information about IPv4 MDT Sessions in BGP
Configuration Examples for the MDT Address Family
Configuring an IPv4 MDT Address-Family Session: Example
BGP Multicast Inter-AS (IAS) VPN
First Published: August 9, 2004Last Updated: December 5, 2006The BGP Multicast Inter-AS (IAS) VPN feature introduces the IPv4 multicast distribution tree (MDT) subaddress family identifier (SAFI) in Border Gateway Protocol (BGP). The MDT SAFI is a transitive multicast capable connector attribute that is defined as an IPv4 address family in BGP. The MDT SAFI is designed to support inter-autonomous-system (inter-AS) Virtual Private Network (VPN) peering sessions.
History for the BGP Multicast Inter-AS (IAS) VPN Feature
Finding Support Information for Platforms and Cisco IOS and Catalyst OS Software Images
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.
Contents
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How to Configure an MDT Address Family Session in BGP
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How to Configure an MDT Address Family Session in BGP
This section contains the following tasks:
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Configuring the MDT Address Family in BGP
The mdt keyword has been added to the address-family ipv4 command to configure an MDT address-family session. Perform this task to configure an MDT address family session on a Provider Edge (PE) routers to establish VPN peering sessions with Customer Edge (CE) routers and to establish inter-AS multicast VPN peering sessions. The MDT address family must be configured on each participating PE router.
Supported Policy
The following policy configuration parameters are supported under the MDT SAFI:
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Prerequisites
Before Inter-AS VPN peering can be established through an MDT address family, MPLS and CEF must be configured in the BGP network and multiprotocol BGP on PE routers that provide VPN services to CE routers.
Restrictions
The following policy configuration parameters are not supported:
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SUMMARY STEPS
1.
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3.
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5.
DETAILED STEPS
Clearing IPv4 MDT Peering Sessions in BGP
Perform this task to clear only MDT address-family routing tables using the new mdt keyword in one of the various forms of the clear ip bgp command. Due to the complexity of some of the keywords available for the clear ip bgp command, some of the keywords are documented as separate commands.
SUMMARY STEPS
1.
2.
3.
4.
DETAILED STEPS
Step 1
enable
Example:Router> enable
Enables privileged EXEC mode.
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Step 2
clear ip bgp ipv4 {multicast | mdt | unicast} autonomous-system-number [in [prefix-filter]] [out] [soft [in [prefix-filter] | out]]
Example:Router# clear ip bgp ipv4 mdt 65700
(Optional) Resets BGP connections for IPv4 address family sessions.
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Step 3
clear ip bgp [ipv4 mdt] peer-group peer-group-name [in [prefix-filter]] [out] [soft [in [prefix-filter] | out]]
Example:Router# clear ip bgp ipv4 mdt peer-group group12 soft in
(Optional) Resets BGP connections using hard or soft reconfiguration for all the members of a BGP peer group.
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Note
Step 4
clear ip bgp [ipv4 mdt] update-group [index-group | neighbor-address]
Example:Router# clear ip bgp ipv4 mdt update-group 3
(Optional) Resets BGP connections for all the members of a BGP update group.
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Note
Displaying Information about IPv4 MDT Sessions in BGP
The show ip bgp ipv4 mdt command can be used to display MDT address-family session information.
SUMMARY STEPS
1.
2.
DETAILED STEPS
Configuration Examples for the MDT Address Family
The following example shows how to configure the MDT address family:
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Configuring an IPv4 MDT Address-Family Session: Example
The following example creates an IPv4 MDT address family session:
enableconfigure terminalrouter bgp 65535address-family ipv4 mdtexit-address-familyAdditional References
The following sections provide references related to the BGP Multicast Inter-AS (IAS) VPN feature.
Related Documents
BGP commands
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BGP configuration tasks
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IP Multicast commands
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IP Multicast configuration tasks
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Standards
MDT SAFI
MDT SAFI
http://www.ietf.org/internet-drafts/draft-nalawade-idr-mdt-safi-01.txt
Technical Assistance
Command Reference
This section documents modified commands only.
address-family ipv4 (BGP)
To enter address family configuration mode to configure a routing session using standard IP Version 4 address prefixes, use the address-family ipv4 command in router configuration mode. To exit address family configuration mode and remove the IPv4 address family configuration from the running configuration, use the no form of this command.
address-family ipv4 [mdt | multicast | tunnel | unicast [vrf vrf-name] | vrf vrf-name]
no address-family ipv4 [mdt | multicast | tunnel | unicast [vrf vrf-name] | vrf vrf-name]
Syntax Description
Command Default
IP Version 4 address prefixes are not enabled.
Command Modes
Router configuration
Command History
Usage Guidelines
The address-family ipv4 command replaces the match nlri and set nlri commands.
The address-family ipv4 command places the router in address family configuration mode (prompt: (config-router-af)# from which you can configure routing sessions that use standard IP Version 4 address prefixes. To leave address family configuration mode and return to router configuration mode, type exit.
Note
The tunnel keyword is used to enable the tunnel subaddress family identifier (SAFI) under the IPv4 address family identifier. This SAFI is used to advertise the tunnel endpoints and the SAFI specific attributes (which contain the tunnel type and tunnel capabilities). Redistribution of tunnel endpoints into the BGP IPv4 tunnel SAFI table occurs automatically when the tunnel address-family is configured. However, peers need to be activated under the tunnel address-family before the sessions can exchange tunnel information.
The mdt keyword is used to enable the multicast distribution tree (MDT) SAFI under the IPv4 address family identifier. This SAFI is used to advertise tunnel endpoints for inter-AS multicast VPN peering sessions.
To leave address family configuration mode and return to router configuration mode without removing the existing configuration, enter the exit-address-family command.
Examples
The following example places the router in address family configuration mode for the IP Version 4 address family:
Router(config)# router bgp 50000Router(config-router)# address-family ipv4Router(config-router-af)#Multicast Example
The following example places the router in address family configuration mode and specifies only multicast address prefixes for the IP Version 4 address family:
Router(config)# router bgp 50000Router(config-router)# address-family ipv4 multicastRouter(config-router-af)#Unicast Example
The following example places the router in address family configuration mode and specifies unicast address prefixes for the IP Version 4 address family:
Router(config)# router bgp 50000Router(config-router)# address-family ipv4 unicastRouter(config-router-af)#VRF Example
The following example places the router in address family configuration mode and specifies cisco as the name of the VRF instance to associate with subsequent IP Version 4 address family configuration mode commands:
Router(config)# router bgp 50000Router(config-router)# address-family ipv4 vrf ciscoRouter(config-router-af)#Tunnel Example
The following example places the router in tunnel address family configuration mode:
Router(config)# router bgp 100Router(config-router)# address-family ipv4 tunnelRouter(config-router-af)#
Note
Related Commands
clear ip bgp ipv4
To reset Border Gateway Protocol (BGP) connections using hard or soft reconfiguration for IPv4 address family sessions, use the clear ip bgp ipv4 command in privileged EXEC mode.
clear ip bgp ipv4 {multicast | mdt | unicast} autonomous-system-number [in [prefix-filter]] [out] [soft [in [prefix-filter] | out]]
Syntax Description
Command Modes
Privileged EXEC
Command History
Usage Guidelines
The clear ip bgp ipv4 command can be used to initiate a hard reset or soft reconfiguration. A hard reset tears down and rebuilds the specified peering sessions and rebuilds the BGP routing tables. A soft reconfiguration uses stored prefix information to reconfigure and activate BGP routing tables without tearing down existing peering sessions. Soft reconfiguration uses stored update information, at the cost of additional memory for storing the updates, to allow you to apply new BGP policy without disrupting the network. Soft reconfiguration can be configured for inbound or outbound sessions.
Generating Updates from Stored Information
To generate new inbound updates from stored update information (rather than dynamically generating inbound updates) without resetting the BGP session, you must preconfigure the local BGP router using the neighbor soft-reconfiguration inbound command. This preconfiguration causes the software to store all received updates without modification regardless of whether an update is accepted by the inbound policy. Storing updates is memory intensive and should be avoided if possible.
Outbound BGP soft configuration has no memory overhead and does not require any preconfiguration. You can trigger an outbound reconfiguration on the other side of the BGP session to make the new inbound policy take effect.
Use this command whenever any of the following changes occur:
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Dynamic Inbound Soft Reset
The route refresh capability, as defined in RFC 2918, allows the local router to reset inbound routing tables dynamically by exchanging route refresh requests to supporting peers. The route refresh capability does not store update information locally for nondisruptive policy changes. It instead relies on dynamic exchange with supporting peers. Route refresh is advertised through BGP capability negotiation. All BGP routers must support the route refresh capability.
To determine if a BGP router supports this capability, use the show ip bgp neighbors command. The following message is displayed in the output when the router supports the route refresh capability:
Received route refresh capability from peer.If all BGP routers support the route refresh capability, use the clear ip bgp ipv4 command with the in keyword. You need not use the soft keyword, because soft reset is automatically assumed when the route refresh capability is supported.
Note
Examples
In the following example, a soft reconfiguration is initiated for the inbound sessions for BGP neighbors in IPv4 unicast address family sessions in autonomous system 65400, and the outbound session is unaffected:
Router# clear ip bgp ipv4 unicast 65400 soft inIn the following example, the route refresh capability is enabled on the IPv4 multicast address family BGP neighbors in autonomous system 65000, a soft reconfiguration is initiated for all inbound sessions with the IPv4 multicast address family neighbors, and the outbound session is unaffected:
Router# clear ip bgp ipv4 multicast 65000 inIn the following example, a hard reset is initiated for all BGP neighbor in IPv4 MDT address family sessions in the autonomous system numbered 65700:
Router# clear ip bgp ipv4 mdt 65700Related Commands
clear ip bgp peer-group
To reset Border Gateway Protocol (BGP) connections using hard or soft reconfiguration for all the members of a BGP peer group, use the clear ip bgp peer-group command in privileged EXEC mode.
Syntax Without Address Family Syntax
clear ip bgp peer-group peer-group-name [in [prefix-filter]] [out] [soft [in [prefix-filter] | out]]
Syntax With Address Family Syntax
clear ip bgp [all | ipv4 {multicast | mdt | unicast} | ipv6 {multicast | unicast} | vpnv4 unicast | vpnv6 unicast] peer-group peer-group-name [in [prefix-filter]] [out] [soft [in [prefix-filter] | out]]
Syntax Description
Command Modes
Privileged EXEC
Command History
Usage Guidelines
The clear ip bgp peer-group command is used to initiate a hard reset or soft reconfiguration for neighbor sessions for BGP peer groups. A hard reset tears down and rebuilds the specified peering sessions and rebuilds the BGP routing tables. A soft reconfiguration uses stored prefix information to reconfigure and activate BGP routing tables without tearing down existing peering sessions. Soft reconfiguration uses stored update information, at the cost of additional memory for storing the updates, to allow you to apply new BGP policy without disrupting the network. Soft reconfiguration can be configured for inbound or outbound sessions.
Generating Updates from Stored Information
To generate new inbound updates from stored update information (rather than dynamically generating inbound updates) without resetting the BGP session, you must preconfigure the local BGP router using the neighbor soft-reconfiguration inbound command. This preconfiguration causes the software to store all received updates without modification regardless of whether an update is accepted by the inbound policy. Storing updates is memory intensive and should be avoided if possible.
Outbound BGP soft configuration has no memory overhead and does not require any preconfiguration. You can trigger an outbound reconfiguration on the other side of the BGP session to make the new inbound policy take effect.
Use this command whenever any of the following changes occur:
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Dynamic Inbound Soft Reset
The route refresh capability, as defined in RFC 2918, allows the local router to reset inbound routing tables dynamically by exchanging route refresh requests to supporting peers. The route refresh capability does not store update information locally for nondisruptive policy changes. It instead relies on dynamic exchange with supporting peers. Route refresh is advertised through BGP capability negotiation. All BGP routers must support the route refresh capability.
To determine if a BGP router supports this capability, use the show ip bgp neighbors command. The following message is displayed in the output when the router supports the route refresh capability:
Received route refresh capability from peer.If all BGP routers support the route refresh capability, use the clear ip bgp peer-group command with the in keyword. You need not use the soft keyword, because soft reset is automatically assumed when the route refresh capability is supported.
Note
Examples
In the following example, all members of the BGP peer group named INTERNAL are reset:
Router# clear ip bgp peer-group INTERNALIn the following example, members of the peer group named EXTERNAL in IPv4 multicast address family sessions are reset:
Router# clear ip bgp ipv4 multicast peer-group EXTERNALIn the following example, a soft reconfiguration is initiated for the inbound session with members of the peer group INTERNAL, and the outbound session is unaffected:
Router# clear ip bgp peer-group INTERNAL soft inRelated Commands
clear ip bgp update-group
To reset Border Gateway Protocol (BGP) connections for all the members of a BGP update group, use the clear ip bgp update-group command in privileged EXEC mode.
Syntax Without Address Family Syntax
clear ip bgp update-group [index-group | neighbor-address]
Syntax With Address Family Syntax
clear ip bgp [all | ipv4 {multicast | mdt | unicast} | ipv6 {multicast | unicast} | vpnv4 unicast | vpnv6 unicast] update-group [index-group | neighbor-address]
Syntax Description
Command Modes
Privileged EXEC
Command History
Usage Guidelines
The clear ip bgp update-group command is used to clear BGP update group member sessions. If no keywords or arguments are specified, entering this command will recalculate all update groups. Specific index numbers for update groups and information about update-group membership is displayed in the output of the show ip bgp update-group and debug ip bgp groups commands.
When a change to outbound policy occurs, the BGP routing process will automatically recalculate update-group memberships and apply changes by triggering an outbound soft reset after a 3-minute timer expires. This behavior is designed to provide the network operator with time to change the configuration before the soft reset is initiated. You can immediately initiate the outbound soft reset before the timer expires by entering the clear ip bgp ip-address soft out command or immediately initiate a hard reset by entering the clear ip bgp ip-address command.
Examples
In the following example, the membership of the 10.0.0.1 peer is cleared from an update group:
Router# clear ip bgp update-group 10.0.0.1In the following example, update-group information for all peers in the index 1 update group is cleared:
Router# clear ip bgp update-group 1In the following example, update-group information for all MDT address family session peers in the index 6 update group is cleared:
Router# clear ip bgp ipv4 mdt update-group 6Related Commands
show ip bgp ipv4
To display entries in the IP version 4 (IPv4) Border Gateway Protocol (BGP) routing table, use the show ip bgp ipv4 command in privileged EXEC mode.
show ip bgp ipv4 {mdt {* | all | rd | vrf} | multicast | tunnel | unicast}
Syntax Description
Command Modes
Privileged EXEC
Command History
Examples
The following is sample output from the show ip bgp ipv4 unicast command:
Router# show ip bgp ipv4 unicastBGP table version is 4, local router ID is 10.0.40.1Status codes: s suppressed, d damped, h history, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*> 10.10.10.0/24 172.16.10.1 0 0 300 i*> 10.10.20.0/24 172.16.10.1 0 0 300 i* 10.20.10.0/24 172.16.10.1 0 0 300 iThe following is sample output from the show ip bgp ipv4 multicast command:
Router# show ip bgp ipv4 multicastBGP table version is 4, local router ID is 10.0.40.1Status codes: s suppressed, d damped, h history, * valid, > best, i - internalOrigin codes: i - IGP, e - EGP, ? - incompleteNetwork Next Hop Metric LocPrf Weight Path*> 10.10.10.0/24 172.16.10.1 0 0 300 i*> 10.10.20.0/24 172.16.10.1 0 0 300 i* 10.20.10.0/24 172.16.10.1 0 0 300 iTable 1 describes the significant fields shown in the display.
Related Commands
clear ip bgp ipv4 mdt
Resets multicast discovery tree IPv4 BGP address-family sessions.
show ip bgp
Displays entries in the BGP routing table.
Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.
© 2004, 2006 Cisco Systems, Inc. All rights reserved.
