-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Mon, 26 May 2014 06:39:26 PM Toby Corkindale wrote:
Rather than totally dropping the packet if the destination port doesn't support it, the switch should alert the sender that they must fragment their packets. Path MTU discovery. Although actually I think some (most?) switches instead just do the fragmentation themselves.
That's routers, not switches. TCP will work on a subnet with hosts with different MTUs as you'll have the MSS taking care of that, but UDP won't know and so will do odd things. A long time ago, on a network far far away we put in (unmanaged) gigE switches for (then UDP) NFS traffic and chose switches that explicitly said they supported jumbo frames. Weird things started happening and we then realised that these switches were not doing jumbo frames as advertised. After a brief comic interlude with the vendor saying "turn on jumbo frames in the management interface" to which we replied "which part of 'unmanaged switch' did you not understand?" they ended up shipping out replacement ROMs for the switches and then it all worked. :-) All the best, Chris - -- Chris Samuel : http://www.csamuel.org/ : Melbourne, VIC -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQEVAwUBU4SR0I1yjaOTJg85AQKT2Af/aZlBL/jUEhHc/2O+tQlFJaUkVqduEjDZ A1XFpOVkBf1pu9B/SGQN8/r4cGeBNOD5QWa8SvGL6lTq3Ho5f6ve2oMtaW1ijurN mzc8U4+yKktEy6alpuGN8tvMIpZxkfyLBODsAZLhdbJCHtk7OFYDUlczqUE2ho0U bciUpouCs1D3Fp/zBwUnGaIIu+yWfb98o+Aqco69wh83lHMxVkfBv9hATxwyZ5zp Q+Qom+hD9MIUdzRFLkLXjG3Lu9+fB6BWQLZt70FRLgTuuXSV9jyENeOgxQid4c+C 6T5iJNzWI4rgKXjsy4OlU/qEt6Z5uILbGOCWF3NLsPkB0DAHtvzLTg== =K0yB -----END PGP SIGNATURE-----