[nsp] CEF problem on 6509 (native)

Sorin CONSTANTINESCU adonay at dumnez.eu.org
Wed Nov 12 14:42:07 EST 2003


I found out what the problem is (with some help from the list), but i
don't know how i can get rid of it.

The router has a mls cef entry for x.y.z.25 different from x.y.z.0/24,
when in the routing table i have only entry, for x.y.z.0/24:

r2#show mls cef x.y.z.0

Index      Prefix           Mask                Adjacency
13429      x.y.z.0       00d0.0568.980a
r2#show mls cef x.y.z.25

Index      Prefix           Mask                Adjacency
2240       x.y.z.25     00a0.d2a4.5003

This client is connected via a cable-modem. The CMTS is Cuda (router, not

I don't get it from where does this router learn that mls cef entry. The
layer3 path is

r2 --> r1 --> CUDA CMTS --> client

I've even monitored CUDA's traffic for 00a0.d2a4.5003 or x.y.z.25 to see
what packets come/go when the mls cef entry is renewed, but i haven't seen

r2 does not have any interface in the vlan in which the CUDA CMTS is

I really don't know what to do next. If there's anything i forgot to add,
please drop pe an email.

adonay at dumnez.eu.org
Linux Registered User #222086

> On 11/11/03 2:35 AM, "Sorin CONSTANTINESCU" <adonay at dumnez.eu.org> wrote:
>> Hi,
>> One of our Cat6500 routers' CEF is acting strangely. The router wouldn't
>> forward traffic towards x.y.z.25, but it would for x.y.z.26. CEF has an
>> entry for x.y.z/24 (known by the router from BGP).
>> If i put an ACL on a VLAN (in) with permit for x.y.z.25, traffic coming
>> via that vlan will be routed, but only the traffic coming via that vlan.
>> The temporary solution was to have a route for x.y.z.25.
>> The 6509 has msfc2/sup2, and runs Version 12.1(19)E (native). I looked
>> for
>> CEF bugs using cisco's bugtool, but none match
>  my case.
>> Does anybody have a clue on how to solve this problem?
>> Regards,

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