[nsp] CEF problem on 6509 (native)

[Siva Valliappan]

Hi Sorin,

   are you doing proxy arp by any chance?  are you receiving a gratuitous
arp for the .25 address from the device with the mac address
00a0.d2a4.5003?  what device has the mac address 00a0.d2a4.5003?

cheers
.siva



On Thu, 13 Nov 2003, Sorin CONSTANTINESCU wrote:

>
> 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,
> >>>
>
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