North American Network Operators Group

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Re: Service Provider Exchange requirements

  • From: hardie
  • Date: Mon Oct 23 13:55:13 2000

> If your switch is MCAST aware, you should be able to keep mcast traffic on
> ports tagged for it to begin with.  If your switch isn't mcast aware. you
> need to find a new switch.

MCAST aware means different things in different environments.  Ideal
is a switch that knows which multicast groups a particular port has
joins on, rather than simply whether or not it is getting multicast
traffic.  In an ethernet fabric used as an exchange point, you have
inter-AS multicast traffic, so sniffing IGMP doesn't do any good.
Sniffing PIM sparse mode for joins would work.  In some environments,
you might be able to use RGMP to tell the switch which groups have
been joined on a particular port (John Meylor mentioned over beer at
the Cogent social that his group might consider writing up RGMP as an
informational draft, so that number of enviornments may go up).

> As for jumbo frames, will someone remind me what the benefit of using a
> larger MTU on the edges than you have in the core is?  Is the edge device
> going to aggregate 6 1500-byte packets into a single 9000-byte jumbo frame
> for me?n

If it is not clear, I am talking about using jumbo frames on ethernet
VLAN used in an exchange point; this would provide a migration path
for service providers who have jumbo frames to the edge, because they
could trade them over the exchange point frabric.  They could, of course,
do the same thing over a private interconnection.
						Ted Hardie