Information Technology Reference
In-Depth Information
Remote Addresses Redistributed into the Local IGP
Figure 10-21 shows how prefixes and labels are exchanged using redistribution in a sample
topology. When RR1 advertises the VPNv4 prefix to RR2, the next hop is still PE1. The
same next hop is maintained on PE2; thus, the VPN label, Lv, is the same from PE1 to PE2.
Figure 10-21 Label Exchange with Multihop eBGP Between RRs Using Redistribution
100:1:172.16.0.0/16
NH=PE1, RT=100:1
VPNv4 Label=Lv
100:1:172.16.0.0/16
NH=PE1, RT=100:1
VPNv4 Label=Lv
100:1:172.16.0.0/16
NH=PE1, RT=100:1
VPNv4 Label=Lv
RR1
RR2
192.168.100.2/32
NH=PE1
IGP Label=L1
192.168.100.2/32
NH=RR1
IGP Label=L2
192.168.100.2/32
NH=ASBR2
IGP Label=L4
192.168.100.2/32
NH=RR2
IGP Label=L5
192.168.100.2/32
NH=ASBR1
BGP Label=L3
PE1
ASBR2
ASBR1
PE2
AS 100
AS 200
Example 10-25 shows the sample BGP configurations on RR1. There are two VPNv4
sessions on RR1: one to PE1 (192.168.100.2) and one to RR2 (192.168.100.7).
Example 10-25 BGP Configurations on RR1
router bgp 100
no synchronization
bgp router-id 192.168.100.3
no bgp default ipv4-unicast
bgp log-neighbor-changes
neighbor Internal peer-group
neighbor Internal remote-as 100
neighbor Internal update-source Loopback0
neighbor Internal activate
neighbor 192.168.100.2 peer-group Internal
neighbor 192.168.100.7 remote-as 200
neighbor 192.168.100.7 ebgp-multihop 3
neighbor 192.168.100.7 update-source Loopback0
no auto-summary
!
address-family vpnv4
neighbor 192.168.100.2 activate
neighbor 192.168.100.2 route-reflector-client
neighbor 192.168.100.2 send-community extended
neighbor 192.168.100.7 activate
neighbor 192.168.100.7 next-hop-unchanged
 
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