Exchanging Vpn Routing Information - Cisco CRS Configuration Manual
Ios xr virtual private network
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Implementing MPLS Layer 3 VPNs
4 The eBGP border edge router (ASBR2) redistributes the route in one of the following ways, depending
on the configuration:
This option is not supported for Inter-AS over IP tunnels.
Note
Exchanging VPN Routing Information
Autonomous systems exchange VPN routing information (routes and labels) to establish connections. To
control connections between autonomous systems, the PE routers and eBGP border edge routers maintain a
label forwarding information base (LFIB). The LFIB manages the labels and routes that the PE routers and
eBGP border edge routers receive during the exchange of VPN information.
The autonomous systems use the following guidelines to exchange VPN routing information:
• Routing information includes:
• A route distinguisher (RD1). A route distinguisher is part of a destination network address. It makes the
• If the iBGP neighbors are configured with the next-hop-self command, ASBR2 changes the next-hop
address of updates received from the eBGP peer, then forwards it.
• If the iBGP neighbors are not configured with the next-hop-self command, the next-hop address
does not get changed. ASBR2 must propagate a host route for the eBGP peer through the IGP. To
propagate the eBGP VPN-IPv4 neighbor host route, use the redistribute command with the static
keyword. An eBGP VPN-IPv4 neighbor host route must be manually confgured to establish the LSP
towards ASBR1. The static route needs to be redistributed to IGP, to let other PE routers use the /32
host prefix label to forward traffic for an Inter-AS VPN redistribute static option.
• The destination network (N)
• The next-hop field associated with the distributing router
• A local MPLS label (L)
VPN-IPv4 route globally unique in the VPN service provider environment.
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
Exchanging VPN Routing Information
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