[afnog] MTU Size for transit links for ISPs

Randy Bush randy at psg.com
Sat Sep 21 23:02:35 UTC 2013


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> In general, the MTU across IP Transit links (i.e., between 
> your and your upstream's border routers, or between your 
> peering router and those of other networks) is about 1,500 
> bytes.
> 
> The MTU within your core (or core of the network your 
> connected to) would, these days (although not always), be 
> larger than what is supported across the peering link.

if we assume s/peering/external/.  and for most networks, is
not the vast majority of the traffic external.  thus, will the
above advice not cause your border routers to have to fragment
all outbound traffic?

it might be good to negotiate higher mtus with external links.

randy
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