Information Technology Reference
In-Depth Information
Example 10-52
Relevant Configurations on PE2 (Continued)
neighbor 192.168.100.7 activate
neighbor 192.168.100.7 send-label
no auto-summary
!
address-family ipv4 vrf VPNa
neighbor 192.168.48.8 remote-as 65000
neighbor 192.168.48.8 activate
neighbor 192.168.48.8 as-override
no auto-summary
no synchronization
exit-address-family
!
address-family vpnv4
neighbor 192.168.100.7 activate
neighbor 192.168.100.7 send-community extended
no auto-summary
exit-address-family
When the VPN prefix 172.16.0.0 is advertised from PE1 to RR1, a VPN label 24 is assigned,
as shown in Example 10-53. (For a graphical representation of prefix and label distribution,
refer to Figure 10-22.) The BGP next hop is CE1 but is reset to PE1 when the route is
advertised to RR1 (shown next).
Example 10-53
BGP Label for 172.16.0.0 on PE1
PE1#show ip bgp vpnv4 all label
Network Next Hop In label/Out label
Route Distinguisher: 100:100 (VPNa)
172.16.0.0 192.168.12.1 24/nolabel
The same VPN label is used when RR1 advertises the prefix to RR2, as shown in
Example 10-54. The BGP next hop is PE1. Also, RR2 advertises the same label when it
advertises the prefix to PE2 (not shown).
Example 10-54
BGP Label for 172.16.0.0 on RR1
RR1#show ip bgp vpnv4 all label
Network Next Hop In label/Out label
Route Distinguisher: 100:100
172.16.0.0 192.168.100.2 nolabel/24
For this inter-AS VPN to work, loopback addresses of RRs and PEs must be reachable via
an LSP in the remote AS. The following examines how PE1's loopback address plus labels
are received on PE2, forming an end-to-end LSP.
