[nsp] CEF problem on 6509 (native)

[Sorin CONSTANTINESCU]

Hi again,

Now, the CUDA CMTS is connected to our network via a routed port, not a
switched one and the problem still exists.

Client -- cable modem -- cuda -- R1 -- R2

Still, R2 sees in it's mls cef table an entry pointing to my client's MAC
address:

r2#show ip route x.y.z.25
Routing entry for x.y.z.0/24
  Known via "bgp 8708", distance 200, metric 0, type internal
  Last update from a.b.c.d 5d06h ago
  Routing Descriptor Blocks:
  * a.b.c.d, from a.b.c.d, 5d06h ago
      Route metric is 0, traffic share count is 1
      AS Hops 0

r2#sh ip cef a.b.c.25
x.y.z.0/24, version 5658497, epoch 0, cached adjacency a.b.c.d
170330 packets, 10848340 bytes
  via a.b.c.d, 0 dependencies, recursive
    next hop a.b.c.d, Vlan2 via a.b.c.d/32
    valid cached adjacency
r2#show mls cef x.y.z.25 255.255.255.255

Index      Prefix           Mask                Adjacency
2752       x.y.z.25      255.255.255.255     00a0.d2a4.5003
r2#sh clock
18:25:57.411 EETDST Thu Nov 13 2003
r2#

a.b.c.d is the IP address of r1 (the router Cuda is connected in).r1 and
r2 are directly connected via Vlan2, as seen in the show ip cef.

Regards,
-- 
Sorin CONSTANTINESCU
adonay at dumnez.eu.org
Linux Registered User #222086

Sorin CONSTANTINESCU said:
>
> No, the address is the same for 2 months, at least.
>
> --
> Sorin CONSTANTINESCU
> adonay at dumnez.eu.org
> Linux Registered User #222086
>
> Jack.W.Parks at alltel.com said:
>> Did you happen to readdress the link with a new IP address?  For
>> example:  The link toward the CMTS was 1.1.1.1/30, but recently you
>> changed it to 2.2.2.1/30.
>>
>> We have had many problems related to this type of change and CEF.  The
>> ONLY fix was to reload the router after any destination next-hop change.
>>
>> Jack
>>
>> Jack W. Parks IV
>> Sr. Network Engineer
>> ALLTEL Communications
>> jack.w.parks at remove-me.alltel.com
>> Work: 501-905-5961
>> Cell: 501-680-3341
>>
>>
>> -----Original Message-----
>> From: cisco-nsp-bounces at puck.nether.net
>> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Sorin
>> CONSTANTINESCU
>> Sent: Wednesday, November 12, 2003 1:42 PM
>> To: cisco-nsp at puck.nether.net
>> Subject: Re: [nsp] CEF problem on 6509 (native)
>>
>>
>>
>> Hi,
>>
>> 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.0 255.255.255.0
>>
>> Index      Prefix           Mask                Adjacency
>> 13429      x.y.z.0       255.255.255.0       00d0.0568.980a
>> r2#show mls cef x.y.z.25 255.255.255.255
>>
>> Index
>   Prefix           Mask                Adjacency
>> 2240       x.y.z.25      255.255.255.255     00a0.d2a4.5003
>> r2#
>>
>> This client is connected via a cable-modem. The CMTS is Cuda (router,
>> not bridge).
>>
>> I don't get it from where does th
>> is 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 any.
>>
>> r2 does not have any interface in the vlan in which the CUDA CMTS is
>> connected.
>>
>> I really don't know what to do next. If there's anything i forgot to
>> add, please drop pe an email.
>>
>> Thanks!
>> --
>> Sorin CONSTANTINESCU
>> 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,
>>>