[cisco-bba] IOS upgrade kills Linksys

[Krzysztof Adamski]

I did not bring the tunnel down, so I guess I did not try it without the
mtu adjust, but I have to many users on the tunnel to bounce it.

K

On Fri, 8 Oct 2004, Dennis Peng wrote:

> If you remove it, it won't take effect until the entire L2TP tunnel
> goes down and comes back up.
>
> Dennis
>
> Krzysztof Adamski [k at adamski.org] wrote:
> > 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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>