> From: Darren Reed [mailto:avalonat_private] > In some mail from Russ, sie said: > I think some people are not understanding the difference between the > TCP MSS and IP's MTU. Either that or both you and David LeBlanc are > grasping at straws in order to make WindowsNT look better ;) I understand that difference. I'm not grasping at straws, I'm just wrong. Ooops. This happens occasionally. <struggles to get foot out of mouth...> > MTU and Path MTU (PMTU) discovery are not the same as TCP's > MSS but they > can and do impact it. Understood. I was hoping that if you turned off PMTU discovery, that it would also ignore MSS and just send default sized packets. Unfortunately, I don't think that's the case. Doh! > Given all of the above, the suggestion both you and David LeBlanc made > that Windows fixed things at a default of 576 when PMTU discovery was > enabled is not true and I proved this in testing. OK, OK, you win. I'm sure you meant to write: "when PMTU discovery was DISabled" > and so on. Essentially, on both of those platforms all it does is > control whether the "don't fragment" bit (0x4000) is set in the IP > offset field. Actually, a bit more than that - it also means that it drops the rest of the PMTU discovery process and uses a default value, apparently unless the client specifies something else. <falls back, punts...> >I get the same lack of an > answer on how to set a minimum acceptable MSS now as I did then. I'll see what I can come up with.
This archive was generated by hypermail 2b30 : Tue Jul 10 2001 - 07:06:31 PDT