OSPF Sham-Link Support for MPLS VPN
Supported Platforms
8
Cisco IOS Release 12.2(8)T

Restrictions

When OSPF is used as a protocol between PE and CE routers, the OSPF metric is preserved when routes
are advertised overthe VPN backbone. The metric is used on the remote PE routers to select the correct
route. For this reason, you should not modify the metric value when OSPF is redistributed to BGP,and
when BGP is redistributed to OSPF. If you modify the metric value, routing loops may occur.

Related Features and Technologies

MPLS
OSPF
BGP

Related Documents

Cisco IOS Configuration Fundamentals Configuration Guide,Release 12.2
Cisco IOS Configuration Fundamentals Command Reference,Release 12.2
Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols, Release 12.2
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fiprrp_r/1rfospf.htm
MPLS Virtual Private Networks
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t5/vpn.htm
Configuring OSPF
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt2/1cfospf.
htm
Configuring BGP
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt2/1cfbgp.h
tm
RFC 1163, A Border Gateway Protocol
RFC 1164, Application of the Border Gateway Protocol in the Internet
RFC 2283, Multiprotocol Extensions for BGP-4
RFC 2328, Open Shortest Path First, Version 2
RFC 2547, BGP/MPLS VPNs
Supported Platforms
Cisco 1400 series
Cisco 1600
Cisco 1600R
Cisco 1710
Cisco 1720