[c-nsp] Sup720 - FIB full, software switching

["Rolf Hanßen"]

Hi,

indeed, the limiter was installed.

kind regards
Rolf

> One other thing I noticed from your email and something that we've
> experienced in the past as well.  I think it may also be related to
> hitting the TCAM limit but check to see if you have this command enabled:
>
> mls rate-limit unicast cef receive 10000 255
>
> According to Cisco, that command will automatically get added to your
> config when the tables get full.  That command will start to drop
> packets and unless you look for it you wouldn't know it's there because
> generally it's not.  All BGP sessions appear normal and none of your
> interfaces show full yet you're still dropping packets.  Cisco advised
> us to increase the receive to 1000000 to avoid any possible issues in
> the future.
>
> Thanks to the other replies about having to reload the switch to clear
> the TCAM exception.  I didn't know that once you hit it that the only
> way to fix it was to completely reload the box.
>
> Jose
>
> On 2/3/2014 9:09 AM, "Rolf Hanßen" wrote:
>> Hi,
>>
>> today I saw 2x Sup720-3B (default 192K IPv4 routes) that received a full
>> table.
>> After FIB was filled IOS gave a warning that it now may forward in
>> software (and resetted all BGP sessions because of memory issues). I
>> don't
>> have the exact messages.
>>
>> The real problem occured after that. I shut the full table BGP session
>> and
>> cleared the others, the system now had a few routes only again.
>>
>> But it started to drop packets, I saw no pattern, it looked nearly
>> random.
>> I needed to reboot both boxes to resolve that issue.
>>
>> IOS was s72033-advipservicesk9_wan-mz.122-33.SXJ.bin
>>
>> Is there a way to avoid those issues by let it just ignoring routes not
>> matching into the FIB?
>> Is there a command to reset the routing mode/routes back to CEF without
>> reloading the box?
>>
>> kind regards
>> Rolf
>>
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