[nsp] /30 over WAN links

Niels Bakker niels=cisco-nsp at bakker.net
Fri Feb 6 15:00:57 EST 2004

>> -----Original Message-----
>> From: Roman Volf [mailto:volfman at keystreams.com]
>> Does anyone out there use private RFC1918 address for PTP links? Does 
>> this break anything?

* cchurch at wamnetgov.com (Church, Chuck) [Fri 06 Feb 2004, 20:54 CET]:
> If you're filtering bogons, it'll affect traceroutes.  Not a real big issue, though.

Actually, it breaks something quite important: Path MTU Discovery,
if you have discrepancies in MTU sizes in your network, like PPPoE,
and the other party filters bogons (as they should).

In general, it's a bad idea, that goes much beyond traceroutes.
Please don't follow Mr CCIE's advice.  RFC1918 space is for networks
not connected to the Internet.

This subject is a recurring thread on the NANOG mailing list...

	-- Niels.


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