Re: Peering versus Transit

["Alex.Bligh" <amb () xara net>]

> I think Mr. Simpson was referring to the outbound traffic in this case, not
> FULL transit.  Of course you have to manage a way for that traffic's return
> packets to find you.  In a lot of ISPs cases, the outbound traffic is a 3:1
> ratio.  So if you can dump your outbound traffic onto an unknowing IXP 
> member, your probably in luck.  Then just simply order an SMDS connection to
> CIX for the return path at ever-so-fast lightspeed.

Presumably most people monitor for this though or they deserve
all they get....

One simple way to check for people defaulting at you is to ping
from an IP address which is not in the routing table one of their
IP addresses, and apply a logging filter for dest addresses
of the nonexistant IPaddr on the i/f over which the peering
occurs. If you see ICMP Echos to the nonexistant IP address
you know they are defaulting. (This isn't my original idea -
apols to whoever thought of it originally if they are
reading this).

IP accounting / flow stats are more reliable though.

Alex Bligh
Xara Networks


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