[cisco-bba] IOS upgrade kills Linksys

[Krzysztof Adamski]

I did have "ip mtu adjust" and I removed it, but that did not help.
The client has 5 locations, so far in one he upgraded the firmware on the
linksys and that fixed it, but the other four are not working with the new
firmware. At the second location he replaced the linksys with a gnet box,
so far it is working, we will give some time to make sure that is the
solution before the other locations are changed to gnet.

Somebody here recommended that I add "qos pre-classify" to the
virtual-template, that seem to fix a vpn between a linksys and netgear for
a different customer, I'm really curios why.

K

 On Fri, 8 Oct 2004, Dennis Peng wrote:

> Do you have "ip adjust mtu" under the VPDN group? That will change the
> MTU automatically, but having a lower MTU can cause problems for some
> applications. I usually recommend customers to remove it if they are
> having MTU issues.
>
> Dennis
>
> Krzysztof Adamski [k at adamski.org] wrote:
> > I upgrade my LNS from 12.2(12f) to 12.2(15)T14, and now some LinkSys boxes
> > are showing weird behaviour. The LNS is doing PPPoE aggregation.
> >  All the normal web access is working, but a VPN access to an exchange
> > server is not. The VPN software is running on a PC behind the LinkSys. The
> > VPN packets are encapsulated in UDP.
> >  Not all VPN is the problem just the exchange traffic. Snooping the
> > traffic it appears that the exchange is sending a 18k size UDP packet that
> > is being fragmented. The size of each fragment is 1492 bytes. For some
> > strange reason the MTU on the virtual-interface is 1464, this is how my
> > virtual-template looks:
> >
> > interface Virtual-Template1
> >  ip unnumbered FastEthernet1/0
> >  no ip proxy-arp
> >  mtu 1492
> >  ip tcp adjust-mss 1300
> >  no logging event link-status
> >  peer default ip address pool ADSL
> >  ppp authentication pap
> >
> > I have tried ip mtu 1492, mtu 1500, mtu 1464, even changing the MTU on the
> > LinkSys to 1464 nothing helped.
> >
> > Any ideas what can be wrong?
> >
> > K
> >
> >
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