Cisco Cisco IOS Software Release 12.2(27)SBC

The NSF/SSO—MPLS VPN feature has the following prerequisites:

For information about supported hardware, see the following documents:

For Cisco IOS Release 12.2(25)S, see the 

For Cisco IOS Release 12.2(28)SB, see the 

For Cisco IOS Release 12.2(33)SRA, see the 

For Cisco IOS Release 12.2(33)SXH, see the following documents:

Before enabling Stateful Switchover (SSO), you must enable MPLS Label Distrbution Protocol (LDP) 
Graceful Restart if you use LDP in the core or in the MPLS VPN routing and forwarding instance in an 
MPLS VPN Carrier Supporting Carrier configuration. See the

 feature module for more information. 

You must enable NSF on the routing protocols running between the provider (P) routers , PE routers, and 
customer edge (CE) routers. The routing protocols are:

Border Gateway Protocol (BGP)

Open Shortest Path First (OSPF)

Intermediate System-to-Intermediate System (IS-IS)

Cisco nonstop forwarding support must be configured on the routers for Cisco Express Forwarding. See 
the

 Cisco Nonstop Forwarding

 feature module for more information. 

Before enabling the NSF/SSO—MPLS VPN feature, you must have a supported MPLS VPN network 
configuration. Configuration information is included in the “Part 4: MPLS Virtual Private Networks” 
module in the 

, Release 12.4.

The NSF/SSO—MPLS VPN feature has the following restrictions:

Tag Distribution Protocol (TDP) sessions are not supported. Only LDP sessions are supported.

The NSF/SSO—MPLS VPN feature requires that neighbor networking devices be NSF-aware. Peer 
routers must support the graceful restart of the protocol used to communicate with the 
NSF/SSO—MPLS VPN-capable router.