TalkTalk and DSCP and 19 second latency: Difference between revisions

mNo edit summary
mNo edit summary
 
This page is about in interesting problem that was reported to us, by a customer, in December 2021. We have written this up so that this page can be found if other people are seeing a similar problem.
 
We've masked the IP we're pinging in this page as it doesn't matter what IP you ping - in our tests though we were mostly pinging the IP of our LNS, as that is the 'next hop' on the customer's route to the internet.
 
 
=TL;DR=
 
ping -i 0.02 -z 192 -s 1400 -c 100 81.187.81.18
PING 81x.187x.81x.187x (81x.187x.81x.187x): 1400 data bytes
1408 bytes from 81x.187x.81x.187x: icmp_seq=0 ttl=63 time=10.234 ms
Request timeout for icmp_seq 10
1408 bytes from 81x.187x.81x.187x: icmp_seq=10 ttl=63 time=37.160 ms
1408 bytes from 81x.187x.81x.187x: icmp_seq=11 ttl=63 time=16.935 ms
1408 bytes from 81x.187x.81x.187x: icmp_seq=20 ttl=63 time=278.065 ms
1408 bytes from 81x.187x.81x.187x: icmp_seq=30 ttl=63 time=386.798 ms
Request timeout for icmp_seq 70
1408 bytes from 81x.187x.81x.187x: icmp_seq=40 ttl=63 time=793.062 ms
Request timeout for icmp_seq 80
1408 bytes from 81x.187x.81x.187x: icmp_seq=50 ttl=63 time=836.497 ms
1408 bytes from 81x.187x.81x.187x: icmp_seq=60 ttl=63 time=1040.796 ms
1408 bytes from 81x.187x.81x.187x: icmp_seq=70 ttl=63 time=1453.866 ms
1408 bytes from 81x.187x.81x.187x: icmp_seq=80 ttl=63 time=1461.298 ms
1408 bytes from 81x.187x.81x.187x: icmp_seq=90 ttl=63 time=1935.554 ms
1408 bytes from 81x.187x.81x.187x: icmp_seq=99 ttl=63 time=1978.546 ms
100 packets transmitted, 100 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 9.734/929.728/2047.155/628.466 ms
 
This only goes up to just under 2 seconds, but if left, it will peak and continue to run at 19 seconds:
1408 bytes from 81x.187x.81x.187x: icmp_seq=986 ttl=63 time=19084.589 ms
 
Whilst latency is shown to traffic tagged with DSCP CS6, all other traffic is unaffected, everything else has normal (good) latency.
Retrieved from ‘http://support.aa.net.uk/TalkTalk_and_DSCP_and_19_second_latency’