Example 613 Key Configurations for the Network Shown in Figure 613

On the CPE: router bgp 100 neighbor 4.4.4.4 route-map setcom-voice out route-map setcom-voice match ip address 101 set community 1:1

access-list 101 permit ip host 1.1.1.1 host 255.255.255.255

On RouterG (the tunnel tail)

router bgp 100

neighbor 1.2.3.4 route-map set-nh in route-map set-nh match community 1 set ip next-hop 5.5.5.5

ip community-list 1 permit 1:1

ip route 5.5.5.5 255.255.255.255 Tunnel1

Doing things this way means that the only one who needs to know which routers are VoIP routers and which aren't is the CPE; the administration of any static configuration is limited to the CPE. As more VoIP and CPE routers are added off RouterG, the tunnel headends don't need to change anything. As more tunnel tails are added, the tunnel headends need to add only a single static route per DS-TE tunnel to that tail.

You can also be more flexible than using a community. RouterG can change the next hop based on any criteria, because BGP is flexible in what it supports. Rather than a community, you could change the next hop based on the destination AS, for example, or perhaps a transit AS. The choice is up to you.

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