VRF Select is supported only in Service Provider (-p-) images.
Unidirectional Traffic
This is a unidirectional feature and can only be used from a customer (IP-based) network into a provider (MPLS-based) network. This feature cannot be used from a provider network to a customer network.
Subnet Masks
Subnet masks should be kept as short as possible for Engine 2 line cards. Performance can degrade with longer subnet masks (/24 or /32, for example).
traceroute Command
An IP traceroute command from a customer edge (CE) router that has this featue enabled to a typical MPLS VPN VRF CE router works as expected. However, an IP traceroute command from a typical MPLS VPN VRF CE router to a CE router that has this feature enabled may fail to show all the relevant hop information across the core.
Supported Static Route Configurations
When configuring static routes in an MPLS or MPLS VPN environment, some variations of the ip route and ip route vrf commands are not supported. These variations of the commands are not supported in Cisco IOS releases that support the Tag Forwarding Information Base (TFIB), specifically Cisco IOS Releases 12.xT, 12.xM, and 12.0S. The TFIB cannot resolve prefixes when the recursive route over which the prefixes travel disappears and then reappears. However, the command variations are supported in Cisco IOS releases that support the MPLS Forwarding Infrastructure (MFI), specifically Cisco IOS Release 12.2(25)S and later. Use the following guidelines when configuring static routes.
Supported Static Routes in an MPLS Environment
The following ip route command is supported when you configure static routes in MPLS environment:
ip route destination-prefix mask interface next-hop-address
The following ip route commands are supported when you configure static routes in an MPLS environment and configure load sharing with static nonrecursive routes and a specific outbound interface:
ip route destination-prefix mask interface1 next-hop1
ip route destination-prefix mask interface2 next-hop2
Unsupported Static Routes in an MPLS Environment that Uses the TFIB
The following ip route command is not supported when you configure static routes in an MPLS environment:
ip route destination-prefix mask next-hop-address
The following ip route command is not supported when you configure static routes in an MPLS environment and enable load sharing where the next hop can be reached through two paths:
ip route destination-prefix mask next-hop-address
The following ip route command is not supported when you configure static routes in an MPLS environment and enable load sharing where the destination can be reached through two next hops:
ip route destination-prefix mask next-hop1
ip route destination-prefix mask next-hop2
Use the interface and next-hop arguments when specifying static routes.
Supported Static Routes in an MPLS VPN Environment
The following ip route vrf commands are supported when you configure static routes in a MPLS VPN environment, and the next hop and interface are in the same VRF:
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ip route vrf vrf-name destination-prefix mask next-hop-address
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ip route vrf vrf-name destination-prefix mask interface next-hop-address
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ip route vrf vrf-name destination-prefix mask interface1 next-hop1
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ip route vrf vrf-name destination-prefix mask interface2 next-hop2
The following ip route vrf commands are supported when you configure static routes in a MPLS VPN environment, and the next hop is in the global table in the MPLS cloud in the global routing table. For example, these commands are supported when the next hop is pointing to the Internet Gateway.
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ip route vrf vrf-name destination-prefix mask next-hop-address global
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ip route vrf vrf-name destination-prefix mask interface next-hop-address (This command is supported when the next hop and interface are in the core.)
The following ip route commands are supported when you configure static routes in a MPLS VPN environment and enable load sharing with static nonrecursive routes and a specific outbound interfaces:
ip route destination-prefix mask interface1 next-hop1
ip route destination-prefix mask interface2 next-hop2
Unsupported Static Routes in an MPLS VPN Environment that Uses the TFIB
The following ip route command is not supported when you configure static routes in a MPLS VPN environment, the next hop is in the global table in the MPLS cloud within the core, and you enable load sharing where the next hop can be reached through two paths:
ip route vrf destination-prefix mask next-hop-address global
The following ip route commands are not supported when you configure static routes in a MPLS VPN environment, the next hop is in the global table in the MPLS cloud within the core, and you enable load sharing where the destination can be reached through two next hops:
ip route vrf destination-prefix mask next-hop1 global
ip route vrf destination-prefix mask next-hop2 global
The following ip route vrf commands are not supported when you configure static routes in an MPLS VPN environment, and the next hop and interface are in the same VRF:
ip route vrf vrf-name destination-prefix mask next-hop1
ip route vrf vrf-name destination-prefix mask next-hop2
Supported Static Routes in an MPLS VPN Environment Where the Next Hop Resides in the Global Table on the CE Router
The following ip route vrf command is supported when you configure static routes in a MPLS VPN environment, and the next hop is in the global table on the CE side. For example, the following command is supported when the destination-prefix is the CE router's loopback address, as in EBGP multihop cases.
ip route vrf vrf-name destination-prefix mask interface next-hop-address
The following ip route commands are supported when you configure static routes in a MPLS VPN environment, the next hop is in the global table on the CE side, and you enable load sharing with static non-recursive routes and a specific outbound interfaces:
ip route destination-prefix mask interface1 nexthop1
ip route destination-prefix mask interface2 nexthop2