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Beginner

6824-X-LE-40G CPU Utilization

hello all

 

We have two 6824-X-LE-40G configured on VSS for MPLS.

there is a known bug for SLCP process that causes CPU issues where TAC its not giving fast feedback.

is there anyone that deployed these devices in VSS for MPLS, etc with any specific used software that its ruining OK?
now i use Version 15.5(1)SY1 but with older versions i cant bring up VSS over 40g ports (other Bugs :D)

 

thx

 

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Hall of Fame Community Legend

Re: 6824-X-LE-40G CPU Utilization


@mirikucaj1 wrote:

there is a known bug for SLCP process that causes CPU issues where TAC its not giving fast feedback. 



I've got a TAC case for an SLCP spike.  Older IOS works fine.  Same config, newer IOS and the CPU spike to about 85% to 95%.  Developers don't want to fix it because, they say, "it's not critical".  Uh, what?  CPU spikes to 85%-90% is not critical?  

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VIP Expert

Re: 6824-X-LE-40G CPU Utilization

"Developers don't want to fix it because, they say, "it's not critical". Uh, what? CPU spikes to 85%-90% is not critical?"

They might consider it non-critical because a) most forwarding should be done in the hardware's ASICs, so even 100% CPU shouldn't impact that, and b), if the SLCP is a low priority process, other high priority processes can push it aside to obtain necessary CPU cycles.
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Beginner

Re: 6824-X-LE-40G CPU Utilization

yes i am aware that most fw its done on ASIC. but processes like OSPF and STP need CPU. so putting in this system thousands of SVI , VPLS , ospf neighbors etc looks kinda scary when it cant even ping itself without oscillation.
Success rate is 100 percent (10000/10000), round-trip min/avg/max = 1/1/116 ms
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VIP Expert

Re: 6824-X-LE-40G CPU Utilization

It's certainly possible to overload a control plan with valid "important" processes. BTW, "important" processes, like routing protocols, STP, etc., should have higher priority. If they are normally (i.e. without bugs) consuming much CPU, though, your network design might need review. (For example, there's a reason OSPF supports areas of different types, or why there's "dampening" features, or why there are different "flavors" of STP, such as MST, which avoids PVSTP issues with lots of VLANs, or STP edge port configuration options [portfast], etc., etc.)

As to ping, responding to ping is usually considered a low priority task. I.e. it's not unusual to see high max values when you ping a "busy" Cisco network device. Ping is a very basic "it's alive" protocol, its latency measurements shouldn't be expected to be highly accurate. (NB: if you're looking for accurate network latency, you need an application designed for that. For example, Cisco's IP SLA responder works to improve latency measurement over ordinary ping. [NB: a super accurate latency application would place at risk other network device control plane functions.])

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Beginner

Re: 6824-X-LE-40G CPU Utilization

thanks for the replay but i cant run the system with "should/must work" there is sensitive services. i have 7600 and they ate running ok with good cpu. so technically i am making a upgrade and 6800 have a beauty datasheet.
i am just looking for someone that has the same device configuration and looking for feedback.
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VIP Expert

Re: 6824-X-LE-40G CPU Utilization

". . . and looking for feedback."

Well, I think you possibly got that from Leo - his note of TAC's response should be helpful.
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Hall of Fame Community Legend

Re: 6824-X-LE-40G CPU Utilization

I'll need to dig up my notes (and IOS archive) to determine which version is didn't have SLCP spiking.
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Beginner

Re: 6824-X-LE-40G CPU Utilization

as i said earlier i have tried the other/older versions but doesn't work the vss config with 40g vsl. so i have stuck with this version and hoping for a new one from cisco.
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