Packet Forwarding - Cisco CRS Configuration Manual
Ios xr virtual private network
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- Configuration manual (430 pages) ,
- User manual (304 pages) ,
- Command reference manual (155 pages)
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Implementing MPLS Layer 3 VPNs
The following figure is not applicable to Inter-AS over IP tunnels.
Note
Figure 30: Exchanging Routes and Labels with the redistributed Command in an MPLS VPN Inter-AS with ASBRs Exchanging
VPN-IPv4 Addresses
Packet Forwarding
This section is not applicable to Inter-AS over IP tunnels.
Note
The figure below illustrates how packets are forwarded between autonomous systems in an interprovider
network using the following packet method.
Packets are forwarded to their destination by means of MPLS. Packets use the routing information stored in
the LFIB of each PE router and eBGP border edge router.
The service provider VPN backbone uses dynamic label switching to forward labels.
Each autonomous system uses standard multilevel labeling to forward packets between the edges of the
autonomous system routers (for example, from CE-5 to PE-3). Between autonomous systems, only a single
level of labeling is used, corresponding to the advertised route.
A data packet carries two levels of labels when traversing the VPN backbone:
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
Packet Forwarding
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