[c-nsp] Latency Spike

[Darren O'Connor]

An ICMP echo-request requires the CPU on the other side to respond with an ICMP echo-reply. It's quite low priority on the CPU so if it's busy doing something else that reply will be delayed. ICMP is not a great test for latency through a router.



Thanks
Darren
http://www.mellowd.co.uk/ccie



> From: molasian at gmail.com
> Date: Thu, 31 Jul 2014 12:10:55 +0700
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Latency Spike
> 
> Hi All,
> 
> Just experienced spike when doing the continuous ping as the result below:
> 
> 64 bytes from x.x.152.3: icmp_seq=421 ttl=255 time=3.53 ms
> 
> 64 bytes from x.x.152.3: icmp_seq=422 ttl=255 time=2.40 ms
> 
> 64 bytes from x.x.160.152.3: icmp_seq=423 ttl=255 time=1.49 ms
> 
> 64 bytes from x.x.152.3: icmp_seq=424 ttl=255 time=3.15 ms
> 
> 64 bytes from x.x.152.3: icmp_seq=425 ttl=255 time=2.05 ms
> 
> *64 bytes from x.x.152.3: icmp_seq=426 ttl=255 time=107 ms*
> 
> 64 bytes from x.x.152.3: icmp_seq=427 ttl=255 time=47.4 ms
> 
> 64 bytes from x.x.152.3: icmp_seq=428 ttl=255 time=3.77 ms
> 
> 64 bytes from x.x.152.3: icmp_seq=429 ttl=255 time=1.12 ms
> 
> 64 bytes from x.x.152.3: icmp_seq=430 ttl=255 time=1.35 ms
> 
> --- x.x.152.3.152.3 ping statistics ---
> 
> 500 packets transmitted, 500 received, 0% packet loss, time 25285ms
> 
> *rtt min/avg/max/mdev = 0.634/4.021/107.242/9.067 ms, pipe 2*
> 
> 
> I tested this segment by segment (point to point) between the two devices,
> and I still see this latency spike. I assume this is normal in the network
> as router/switch needs time to calculate and send back to source.
> 
> 
> Is There anyone experienced this or anything can cause this ?
> 
> 
> Regards,
> 
> -- 
> Samol Khoeurn
> (855) 077 55 64 02 / (855) 067 41 88 66
> Network Engineer
> Cisco: CCNA/CCNP SP/CCIP/
> Juniper: JNCIA/JNCIS-ENT,SP,SEC/JNCIP-ENT
> www.linkedin.com/in/samolkhoeurn
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/