On Thu, 10 Oct 2002 00:55:24 +0200, Iljitsch van Beijnum said:
You can also get around this by making the first hop the one with the lowest MTU. This is no fun for ethernet-connected stuff, but for dial-up this is easy. Then this box will announce a smaller TCP MSS when the connection is established and there aren't any problems.
Or equivalently, just nail the MSS size for off-site connections down to 512, and accept that you have to send 3 times as many packets as you probably should. As far as I can tell from when pMTU *does* work because all parties concerned actually use reasonable addresses and don't filter 'icmp frag needed', you end up with one of 3 results most of the time: 1) You get a clear 1500 end-to-end. 2) You get an MTU of 1460 because of tunneling. 3) You end up racheted down to 576 because of some ancient IP stack someplace (older versions of end-user SLIP/PPP are famous for this) -- Valdis Kletnieks Computer Systems Senior Engineer Virginia Tech