[30074] in North American Network Operators' Group
Re: RFC 1918
daemon@ATHENA.MIT.EDU (Steven M. Bellovin)
Fri Jul 14 16:28:40 2000
From: "Steven M. Bellovin" <smb@research.att.com>
To: Bennett Todd <bet@rahul.net>
Cc: nanog@merit.edu
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Date: Fri, 14 Jul 2000 15:55:08 -0400
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In message <20000714155415.K19521@oven.com>, Bennett Todd writes:
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>2000-07-14-15:47:22 Steven M. Bellovin:
>> No -- 1918 addresses would only break PMTU if folks did ingress or
>> egress filtering for 1918 addresses.
>
>Wouldn't RFC 1918 addrs on router links only threaten to break
>PMTU --- even in the face of 1918 addr filtering --- if one of
>the routers with an rfc 1918 interface addr did routing between
>interfaces with different MTUs? As best I can see, PMTU discovery
>should work fine traversing RFC 1918 links, and the only addrs
>that need to be passed on out are those of routers where the MTU
>decreases along the path, which would only be routers with different
>MTUs on different interfaces.
Yup. And with most links handling 1500-byte MTUs or above, we don't
see much of that.
--Steve Bellovin
