[cisco-bba] MTU problems?

TC Giufre-Sweetser terry at tdce.com.au
Sat Jun 19 18:25:02 EDT 2004

I have a 3640 terminating L2TP from a ADSL wholesaler.  Certain clients,
using PPPOE or PPPOA, now cant keep ANY tcp session up for more than 3 or
4 packets, to a maximum of 10 seconds worth of traffic. Traffic to the
management interface on the CPE router is fine, traffic to windows XP
boxes is effected as above. The MTU was reduced on their PC to 1460 to
check for that, but the problem remains.  I have MSS adjustments on the VT
on the 3640, to 1420 bytes for tcp syn packets, makes no difference.
Various clients with difference hardware, seem to be fine, no MTU problems
and no fragmentation problems. [Current IOS version is 12.3.9 ED.] All the
combinations of suggestions on the CCO website have been tried, several
different IOS's are been tried, I'm no longer convinced it's MTU at all,
where to from here?

Terence C. Giufre-Sweetser

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