BGP TTL

[Geoff Huston]

At 3/21/2002 07:16 AM, Andrew Partan wrote:
>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.]

max AS path length in the V4 BGP world  ppears to be somewhere between 11 
and 22 (http://www.potaroo.net//bgp2/as6447/bgp-max-aspath-length.html)

and if you keep AS path prepending the number is between 25 and 32 
(http://www.potaroo.net//bgp2/as6447/bgp-max-p-aspath-length.html)

(This view uses the route-views data)

Implies to me that a count to inifinity block TTL in V4 BGP is safely set 
at 64, although what you are stopping is not count to infinity per se a 
degnerate case of BGP timers interacting (at this point I wave my hands and 
point to Craig Labovitz' work where he explained the situations leading to 
various sub-forms of BGP count to infinity!)

   Geoff