multicast TTL settings

[Robert Olson]

What if the required TTL turns out to be something like 127 that is
equivalent to full Mbone span? As I understand things, the admin scoping is
the new preferred mechanism for doing things like this...  or is the state
of mrouting now such that one can push out several Mbps of multicast
traffic on a relatively high ttl and not get lots of people pissed off.

(I guess this is something we may learn empirically soon :-)

--bob

>If we were one organization, like Argonne or even cooperating sites like
>vBNS, we could push out a single configuration for the administrative
>scope.  But as you know, the network infrastructure is based on a bunch of
>different network fiefdoms.  The effort necessary to set up an
>administrative scope across all of these semi-friendly neworks would seem
>to be equivalent to simply setting up multisession bridge links.  That is,
>each site would have to learn how, and then implement, the administrative
>scoping in the routers.
>
>I should rephrase my paragraph above.  How does this sound?
>
>  It may be that each site will have their own policy for what the TTL
>  needs to be in order to participate in Access Grid activities.  This
>  TTL may be influenced by their connectivity provider, such as vBNS, 
>  Abilene, ESNet, or commercial ISP.  Accordingly, part of setting
>  up an Access Grid site should be to discover the appropriate TTL setting
>  necessary to get traffic offsite to other Access Grid participants.
>--
>Bill Nickless    http://www.mcs.anl.gov/people/nickless      +1 630 252 7390
>PGP:0E 0F 16 80 C5 B1 69 52 E1 44 1A A5 0E 1B 74 F7     nickless at mcs.anl.gov