[c-nsp] High latency/jitter at times on a NPE-G1?
Rodney Dunn
rodunn at cisco.com
Thu Jun 1 09:11:51 EDT 2006
If you want to prove it put a sniffer/analyzer on both sides
of the box and time sync the traces.
That is just about the ONLY way you can 100% prove the box
is introducing latency/jitter in the forwarding stream.
There will always be some latency/jitter but it should be
so small it's irrelevant.
What order of magnitude are you talking about?
TAC will have an extremely hard time solving this problem unless
you can prove with a trace when and how much latency the box is
really introducing.
I'd be very amazed if it's the 72xx because it's software forwarding
and once the packet goes in the switching vector it can't be
held up other than if there is congestion for the most part.
Just curious:
can you post a 'sh c7200' output.
Rodney
On Thu, Jun 01, 2006 at 09:52:26AM -0300, Sean Watkins wrote:
> Hi,
>
> I've got a couple of recently upgraded 7206VXRs NPE-400 -> NPE-G1s, that are
> experiencing at times, great amounts of jitter/latency.
>
> Reading over the lists for the past couple of years, there are a variety of
> sources of this; we've gone ahead and opened a tac case 603658197 on it, but
> that seems to be going nowhere.
>
> We've examined the switching paths, they seem good. CEF is confirmed
> running; we've begun turning off almost everything not explicity required
> and still from time to time we see great amounts of jitter/latency.
>
> Any ideas where to start looking? The only thing I see is the BGP
> Router/Scanner process running every minute or so, but our latency spikes
> don't correspond to its invocation?
>
> All interfaces are running at peak, at about 60% utilization.
>
>
> router>show proc cpu | exclude 0.00
> CPU utilization for five seconds: 16%/14%; one minute: 16%; five minutes:
> 17%
> PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
> 30 195780 134972 1450 0.15% 0.08% 0.05% 0 Net
> Background
> 64 5181684 53996 95964 1.59% 1.08% 1.05% 0 IP Background
>
> 159 856 194 4412 0.15% 0.03% 0.09% 3 Virtual Exec
>
> router>show proc cpu | exclude 0.00
> CPU utilization for five seconds: 16%/14%; one minute: 16%; five minutes:
> 17%
> PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
> 30 195780 134974 1450 0.15% 0.08% 0.05% 0 Net
> Background
> 64 5181684 53996 95964 1.59% 1.08% 1.05% 0 IP Background
>
> 159 864 199 4341 0.15% 0.03% 0.09% 3 Virtual Exec
>
> router>show proc cpu | exclude 0.00
> CPU utilization for five seconds: 16%/14%; one minute: 16%; five minutes:
> 17%
> PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
> 30 195780 134974 1450 0.15% 0.08% 0.05% 0 Net
> Background
> 64 5181684 53996 95964 1.59% 1.08% 1.05% 0 IP Background
>
> 159 868 204 4254 0.15% 0.03% 0.09% 3 Virtual Exec
>
> router>show proc cpu | exclude 0.00
> CPU utilization for five seconds: 16%/14%; one minute: 16%; five minutes:
> 17%
> PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
> 30 195780 134974 1450 0.15% 0.08% 0.05% 0 Net
> Background
> 64 5181684 53996 95964 1.59% 1.08% 1.05% 0 IP Background
>
> 159 872 209 4172 0.15% 0.03% 0.09% 3 Virtual Exec
>
> router>show proc cpu | exclude 0.00
> CPU utilization for five seconds: 16%/14%; one minute: 16%; five minutes:
> 17%
> PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
> 30 195780 134974 1450 0.15% 0.08% 0.05% 0 Net
> Background
> 64 5181684 53996 95964 1.59% 1.08% 1.05% 0 IP Background
>
> 159 880 214 4112 0.15% 0.03% 0.09% 3 Virtual Exec
>
> router>show proc cpu | exclude 0.00
> CPU utilization for five seconds: 42%/14%; one minute: 18%; five minutes:
> 18%
> PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
> 52 1249292 18854470 66 0.23% 0.13% 0.11% 0 IP Input
>
> 154 642284 3472343 184 0.15% 0.05% 0.05% 0 BGP Router
>
> 157 11663628 84936 137322 27.43% 3.39% 2.36% 0 BGP Scanner
>
> 159 884 219 4036 0.39% 0.06% 0.09% 3 Virtual Exec
>
> router>show proc cpu | exclude 0.00
> CPU utilization for five seconds: 42%/14%; one minute: 18%; five minutes:
> 18%
> PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
> 52 1249292 18854493 66 0.23% 0.13% 0.11% 0 IP Input
>
> 154 642284 3472345 184 0.15% 0.05% 0.05% 0 BGP Router
>
> 157 11663628 84936 137322 27.43% 3.39% 2.36% 0 BGP Scanner
>
> 159 888 224 3964 0.39% 0.06% 0.09% 3 Virtual Exec
>
> router>show proc cpu | exclude 0.00
> CPU utilization for five seconds: 42%/14%; one minute: 18%; five minutes:
> 18%
> PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
> 52 1249296 18854504 66 0.23% 0.13% 0.11% 0 IP Input
>
> 154 642284 3472345 184 0.15% 0.05% 0.05% 0 BGP Router
>
> 157 11663628 84936 137322 27.43% 3.39% 2.36% 0 BGP Scanner
>
> 159 896 229 3912 0.39% 0.06% 0.09% 3 Virtual Exec
>
> router>show proc cpu | exclude 0.00
> CPU utilization for five seconds: 42%/14%; one minute: 18%; five minutes:
> 18%
> PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
> 52 1249300 18854523 66 0.23% 0.13% 0.11% 0 IP Input
>
> 154 642284 3472359 184 0.15% 0.05% 0.05% 0 BGP Router
>
> 157 11663628 84936 137322 27.43% 3.39% 2.36% 0 BGP Scanner
>
> 159 900 234 3846 0.39% 0.06% 0.09% 3 Virtual Exec
>
> router>
>
> This router is running a full table;
>
> Sean
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