Computer Accessories User Manual

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Cisco IP Solution Center, 3.0: MPLS VPN Management User Guide, 3.0
OL-4344-01
Chapter 1 About Cisco IP Solution Center
About MPLS VPNs
Figure 1-9 VRFs for Sites in Multiple VPNs
VRF Implementation Considerations
When implementing VPNs and VRFs, Cisco recommends you keep the following considerations in
mind:
• A local VRF interface on a PE is not considered a directly-connected interface in a traditional sense.
When you configure, for example, a Fast Ethernet interface on a PE to participate in a particular
VRF/VPN, the interface no longer shows up as a directly-connected interface when you issue a show
ip route command. To see that interface in a routing table, you must issue a show ip route
vrf vrf_name command.
• The global routing table and the per-VRF routing table are independent entities. Cisco IOS
commands apply to IP routing in a global routing table context. For example,
show ip route, and
other EXEC-level show commands—as well as utilities such as ping, traceroute, and telnet—all
invoke the services of the Cisco IOS routines that deal with the global IP routing table.
• You can issue a standard Telnet command from a CE router to connect to a PE router. However, from
that PE, you must issue the following command to connect from the PE to the CE:
telnet CE_RouterName /vrf vrf_name
Similarly, you can utilize the Traceroute and Ping commands in a VRF context.
28558
Multihop MP-iBGP
P
P
PE2PE1
ip vrf site1
rd 100:1
route-target export 100:1
route-target import 100:1
ip vrf site2
rd 100:2
route-target export 100:2
route-target import 100:2
route-target import 100:1
route-target export 100:1
ip vrf site3
rd 100:3
route-target export 100:2
route-target import 100:2
route-target import 100:3
route-target export 100:3
ip vrf site4
rd 100:4
route-target export 100:3
route-target import 100:3
Site 1
Site 1 Site 2 Site 3
VPN A
Site 2
Site 4
VPN C
VPN B
Site 3
VRF
for site 1
(100:1)
Site 1 routes
Site 2 routes
VRF
for site 2
(100:2)
Site 1 routes
Site 2 routes
Site 3 routes
Site 4
VRF
for site 4
(100:4)
Site 3 routes
Site 4 routes
VRF
for site 3
(100:3)
Site 2 routes
Site 3 routes
Site 4 routes