Peering Exchange Configurations

Grzegorz Janoszka Grzegorz at
Thu Apr 8 11:44:14 CDT 2010

On 8-4-2010 18:02, Brad Fleming wrote:
> 1) Is a private AS typically used for the exchange side of the session?


> 2) Are RFC1918 IPs typically used for the p2p links into the exchange?

No. In EU usually it is separate public /24, /23 or /22. The IPv6 range 
in RIPE region for exchanges is assigned from within special pool 
2001:7f8::/32 (each IX gets /48).

> 3) Do peering exchanges typically remove their AS from the path
> advertised to exchange participants?

The direct peering is between participants AS'es, there is nothing in 
between, including IX AS. Route-servers based on Cisco box put their AS 
number in between, but Quagga/Bird usually remove the IX as, however it 
may be configured per peer not to do so.

> 3a) If no: Do participants typically preference exchange-learned routes
> over other sources?

Most do.

> 4) Do exchanges typically support the following address families?
> IPv4 Multicast


> IPv6 Unicast

Almost all.

> IPv6 Multicast


> In exchanges where a route server is employed:
> 4) Do participants have a p2p link into a simple routing environment
> then multi-hop to a route server?

Route-server is just like one of the members of the exchange. You get 
/23 or similar prefix of the exchange. You may have a BGP session with 
the route-server, but you are also free to have direct BGP sessions with 
other parties. Route-servers are mostly used by peers with open peering 
policies, but you still may steer your announcements basing on BGP 

> 5) I see that Bird, OpenBDGd, and Quagga are all options for route
> server software. Does one of those packages stand out as the clear
> current choice for production peering exchanges?

Quagga was used most often, but recently most biggest EU exchanges 
replaced it with Bird and it is much more stable.

Grzegorz Janoszka

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