[c-nsp] CFC linecards on 7600 - traffic punted to RP

[Jiri Prochazka]

Hi,

we're pretty sure that described behaviour is caused by uRPF.

As soon as any mode (loose/strict) of uRPF is enabled on ANY interface 
(even shutdowned), the switch punts all traffic carried on ALL linecards 
equipped with CFC modules to route-processor.

I am able to reproduce this any time.

All I need to do is to boot the switch with clean configuration, 
configure one port as downstream port facing server..and configure any 
SVI/L3 port with 'ip verify unicast' command.

To test if the traffic is being punted to RP I am sending traffic from 
the server destined to some IP wich is Null routed.



Any thoughts where to look?


Thanks!


Jiri




Dne 21.10.2014 22:11, Jiri Prochazka napsal(a):
> Hi,
>
> I am trying to debug strange behaviour on one of our 7600 boxes. All
> packets coming to ports on cards with CFC modules are being punted to RP.
>
> Inventory is following ->
>
> slot 1 WS-X6704 with DFC3CXL
> slot 2 WS-X6704 with DFC3CXL
> slot 3 WS-X6704 with CFC
> slot 4 WS-X6704 with CFC
> slot 6 RSP720-3CXL
>
> IOS 15.2(4)S6
>
> The box is new, configuration has ben taken from the old box with
> sup720. The config itself is absolutely basic, just a few VLANs, some
> etherchannels and trunks.
>
>
> Linecards in slot1&2 are working as expected (no usual traffic is punted
> to RP). They are moving around 20 Gbps of traffic in peaks.
>
> As soon as I move some link from the first two slots to the slot with
> CFC card, it punts ALL incoming traffic on that particular port to CPU.
>
> Does anyone have advice where to start looking?
>
> CEF seems to be fine..
>
> edge-7606s-4#sho cef state
> CEF Status:
>   RP instance
>   common CEF enabled
> IPv4 CEF Status:
>   CEF enabled/running
>   dCEF enabled/running
>   CEF switching enabled/running
>   universal per-destination load sharing algorithm, id 5E18A3C4
> IPv6 CEF Status:
>   CEF enabled/running
>   dCEF enabled/running
>
>
>
> Thank you!
>
>

-- 
Jiri Prochazka
network administrator (AS39392)
SuperNetwork s.r.o.

m: +420 777 87 37 67
w: http://www.superhosting.cz
e: jiri.prochazka at superhosting.cz