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Best Practice where BGP router is "distance" from client

  • From: Sam Stickland
  • Date: Thu Jun 16 07:14:10 2005


I'm wondering what seen as best practice in this network layout:

cisco6500 ==== Network Cloud ==== cisco3550 --- Client

The client needs a full BGP feed, which of course the 3550 is unable to provide, but the cisco 6500 can. The network cloud is relatively simple, and is running IP.

There's a few options:

1) Create a VLAN all the way back from the client to the cisco 6500, and rely on STP/RSTP to provide redundancy over the cloud

2a) Get the client to form a BGP session with the cisco3550 and announce there network(s) to it. The cisco3550 announces our internal address range to the client. Over the top of the this another BGP (multihop) is setup between the client and the 6500. Layer3 protocols (in this case OSPF) provide redundancy in the cloud. Traffic entering our network for the client will be routed straight to the cisco 3550. Traffic from the client will be backhauled all the way to the cisco 6500 before being sent on it's way.

2b) Same as 2a) but with next-hop-unchanged configured on the cisco6500. This should be that traffic leaving the client will be routed from the cisco3550 to the most appropiate network exit-point. The only problem I can see with this senario is if private loopback addresses are in use on the iBGP sessions.

Thoughts? Are there any nasty gotcha's I missed, or pain to be encounted later?