[nsp] Problems with Half Bridge PVC in Access Routers

Gert Doering gert at greenie.muc.de
Sun Nov 30 16:31:42 EST 2003


On Fri, Nov 28, 2003 at 02:53:27PM -0300, Troncoso, Esteban - (Chi) wrote:
> interface ATM0/1/0.10 multipoint
>  mtu 1500
>  ip address
>  no ip directed-broadcast
>  atm pvc 8 0 112 aal5snap bridge
>  no atm enable-ilmi-trap
>  service-policy output C10M

There is big confusion in all places about "correct" MTU values.

The configuration that works well for us (both for sending "big pings"
from our Cisco itself and for "pinging / large-sized TCP packets from 
remote") is:

interface ATM2/0.124 point-to-point
 ip address xx.xx.xx.81
 ip verify unicast reverse-path
 ip mtu 1500
 atm route-bridged ip
 pvc cp7-811 15/124 
  class-vc dsl-2m-e

(that's with route-bridged ip, which is not available in 12.0S, but the
key factor was "ip mtu 1500".  Just setting "mtu 1500" breaks things, as
does *not* setting anything - so we leave the MTU on its default value,
and just set the ip mtu.  We're on 12.2(12a), so maybe it's something
specific to this version and not helpful to you at all...)

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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de

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