[c-nsp] CEF Scanner eating CPU in Supervisor 720

[Peter Salanki]

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Yes, all my MPLS enabled interfaces have very stable L2.

Customer facing interfaces without MPLS on the other hand..

8 jun 2006 kl. 22.06 skrev Rodney Dunn:

> On Thu, Jun 08, 2006 at 09:39:55PM +0200, Peter Salanki wrote:
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>> Yes, we are running MPLS. Does mac changes load CEF Scanner more when
>> MPLS is enabled?
>
> Yes. Sorta confusing but the MPLS TFIB scanner piggybacks on the CEF
> scanner.
>
> On SXF4 you have the fix but one problem we had was:
>
> CSCsb16512
> Externally found moderate defect: Resolved (R)
> High CPU in CEF Process and CEF scanner due to prefix reresolve
>
> A Cisco router may show high CPU in the CEF scanner process with  
> MPLS configured.
> The condition is triggered when an existing arp entry learned on  
> the interface  that is
> mpls enabled changes for an ip address that already exist.
>
> Workaround: None.
>
> What we did there was change it such that if a mac address changes we
> don't reresolve the prefixes for macs that didn't change. We were  
> doing it
> on a per interface before which wasn't too smart.
>
> Your core links with MPLS enabled should be pretty stable at L2 for
> your mac rewrites. That's why you should have a L3 segment that only
> has your MPLS peers on it. VLAN it out or something.
>
> Rodney
>
>  I have a couple of /32s that are repeated a number
>> of times in sh ip cef event. So probably caused by duplicate IPs or
>> something like that, is there any aid for this other than trying to
>> hunt down every broken customer.
>>
>>
>> 8 jun 2006 kl. 19.40 skrev Rodney Dunn:
>>
>>> Are you running MPLS on the box?
>>>
>>> Check the sh ip cef event outut and see if you have a /32 ADJ
>>> for a mac constantly changing. That's the most common trigger
>>> I've seen for the scanner running high.
>>>
>>> You are forcing CEF to constantly reresolve prefixes.
>>>
>>> Rodney
>>>
>>> On Thu, Jun 08, 2006 at 02:23:22PM +0200, Peter Salanki wrote:
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>>>> Hello,
>>>>
>>>> Process "CEF Scanner" is eating average 60% of the CPU on one of my
>>>> Sup720-3BXL. This leads to snmp responses being delayed and full  
>>>> BGP
>>>> updates taking a long time. I have not seen this on any of my other
>>>> sup720s. What differs this box from the rest is that this one has a
>>>> lot of directly connected hosts ~10 SVIs with 300 hosts each  
>>>> (on /23
>>>> subnets). I have tried setting arp timeout to 1200 on those SVIs,
>>>> which resulted in a small CPU utilization decrease. What can I  
>>>> do to
>>>> calm down the CEF Scanner? I'm running 12.2(18)SXF4.
>>>>
>>>> CPU utilization for five seconds: 44%/4%; one minute: 38%; five
>>>> minutes: 38%
>>>> PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY  
>>>> Process
>>>> 119   103495040    719635     143819 35.40% 23.87% 21.54%   0 CEF
>>>> Scanner
>>>>
>>>> Sincerely
>>>>
>>>> Peter Salanki
>>>> Chief Network Engineer
>>>> Bahnhof AB (AS8473)
>>>> www.bahnhof.se
>>>> Office: +46855577132
>>>> Cell: +46709174932
>>>>
>>>>
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>>
>> Sincerely
>>
>> Peter Salanki
>> Chief Network Engineer
>> Bahnhof AB (AS8473)
>> www.bahnhof.se
>> Office: +46855577132
>> Cell: +46709174932
>>
>>
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Sincerely

Peter Salanki
Chief Network Engineer
Bahnhof AB (AS8473)
www.bahnhof.se
Office: +46855577132
Cell: +46709174932


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