Midwest Internet Exchange

What do route servers do?

Transparency Route Servers, unlike regular BGP routers, provide transparency features to facilitate optimal path selection in Internet Exchange infrastructure. FD-IX Route Servers provide the following:

1) AS path transparency by hiding its own ASN. This shortens AS path by one hop and avoids the need for direct peering with other customers on our fabric. There may be other advantages of a direct peer, but that is specific to the individual peer.  For example, some content networks don’t advertise all of their routes to the route server, but will if you establish a direct peer.

2) Next Hop transparency. The route servers will provide original Next Hop address as it is received from the peer. Note that you should never use the route server addresses as Next Hop for any prefix. The servers will drop any traffic not destined to them.

3) MED transparency. This allows optimizing the path in case an AS has two (or more) peers with FD-IX. Note that you can use MED to direct other peer’s customer traffic towards some of your interfaces.  MEDs are encouraged for optimal traffic flow.

Route servers have some unique configuration options due to the next-hop and AS transparency. For example, Cisco IOS needs the command “no bgp enforce-first-as” in the bgp configuration.  IOS-XR does it on a per-neighbor basis. Others call it force next-hop-self. These are commands many folks are not familiar with due to they are not needed for direct peering.

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