BGP TTL

[Andrew Partan]

On Thu, Mar 21, 2002 at 07:00:31AM +1100, Geoff Huston wrote:
> The issue is that the network itself is quite dense (route-views sees an 
> average AS path length of between 3 and 4.5 AS hops for each of the 
> route-views peers) and the average AS path length for address prefixes is 
> noted to be between 2.5 and 3.5 AS hops.
> 
> The question for me is whether a TTL has any practical scope limitation in 
> such a richly interconnected environment.

I thought about this some; settings of 1 or 2 would probably make
the most sense in limiting the scope of the advertisement (much
higher and you are probably reaching the entire internet anyhow).

However even a setting of (say) 10 would limit the count-to-infinity
problem - see, e.g.: the current 6bone & their *very* long AS paths.
[As the 6bone today is mostly full of mutual-transit peerings, you
can get some very long count-to-infinity paths.]

	--asp