On Thu, Jun 02, 2005 at 03:08:32PM -0400, Steven M. Bellovin wrote:
> >That was step 1 on the original email.  Sending a big, 200mb file from 
> >the client 192.168.1.20 to server/gateway 192.168.1.1 is fast.. Full 
> >network speed, 100base xfer rate.  Step 2 was to ftp that file from the 
> >server to an external ftp site on the internet, which is also fast.  
> >It's just when NAT comes into play it initially stalls for several 
> >seconds, then continues very, very slow.
> >
> >For a test, I took my old 1.5Z server on the LAN as 192.168.1.70 and 
> >tried ftping a file from LAN -> internet and it doesn't suffer the same 
> >problem, so this is definately a Windows client issue.  We have four(4) 
> >Windows XP PC's on the LAN, all with XP Pro + SP2 and all of them are 
> >doing this.  They all have Yukon/Marvell Gigabit PCI network adapters so 
> >it's definately a Windoze -> BSD issue instigated sometime between 1.6 
> >and 2.0.2 as the 1.5Z server doesn't have this problem if I place it at 
> >.1 and re-enable NAT.
> >
> >I'm going to keep plugging away and hope if anyone has any recollection 
> >of things either in the SIP driver, NAT or ftp proxy that has changed 
> >that might instigate this behavior.  tcpdump's haven't been too helpful 
> >but I'm still analyzing them.. may attach one if it would be helpful.
> >
> 
> Might it be an MTU issue with PPPoE?  Your original note mentioned DSL.
> I see you have mssclamp specified; is that actually taking effect in 
> the packets sent and received?  What happens if you lower that value to 
> 1420?

Could it also be that the SP2 is blocking ICMP packets ?
From LAN to internet I don't think mssclamp will have any effect, but
the router will probably send ICMP too big messages back to the
clients.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--