[ovs-discuss] Reason Behind different ping latency and way to calculate End to End delay

MA Moyeen mz207303 at dal.ca
Wed Jun 20 13:30:21 UTC 2018


Hi,
I'm getting different ping latency while I ping from one mininet host to another. I'm using Mininet 2.3.0d1, OVS 2.9.90. For single switch topology created with sudo mn I'm also getting the same thing. What could be the reason behind it?
What is the proper way to measure end to end delay from mininet?

Here is the sample ping results
mininet at mininet-vm:~$ sudo mn
*** Creating network
*** Adding controller
*** Adding hosts:
h1 h2
*** Adding switches:
s1
*** Adding links:
(h1, s1) (h2, s1)
*** Configuring hosts
h1 h2
*** Starting controller
c0
*** Starting 1 switches
s1 ...
*** Starting CLI:
mininet> h1 ping -c10 h2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=1 ttl=64 time=22.7 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=2 ttl=64 time=0.199 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=3 ttl=64 time=0.050 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=4 ttl=64 time=0.051 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=5 ttl=64 time=0.046 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=6 ttl=64 time=0.051 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=7 ttl=64 time=0.051 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=8 ttl=64 time=0.071 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=9 ttl=64 time=0.052 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=10 ttl=64 time=0.050 ms

--- 10.0.0.2 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9044ms
rtt min/avg/max/mdev = 0.046/2.339/22.775/6.812 ms
mininet> h1 ping -c10 h2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=1 ttl=64 time=0.046 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=2 ttl=64 time=0.040 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=3 ttl=64 time=0.046 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=4 ttl=64 time=0.051 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=5 ttl=64 time=0.051 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=6 ttl=64 time=0.051 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=7 ttl=64 time=0.051 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=8 ttl=64 time=0.050 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=9 ttl=64 time=0.052 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=10 ttl=64 time=0.052 ms

--- 10.0.0.2 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 8997ms
rtt min/avg/max/mdev = 0.040/0.049/0.052/0.003 ms
mininet> h1 ping -c10 h2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=1 ttl=64 time=5.88 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=2 ttl=64 time=3.36 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=3 ttl=64 time=0.159 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=4 ttl=64 time=0.051 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=5 ttl=64 time=0.050 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=6 ttl=64 time=0.047 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=7 ttl=64 time=0.050 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=8 ttl=64 time=0.040 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=9 ttl=64 time=0.040 ms
64 bytes from 10.0.0.2<http://10.0.0.2/>: icmp_seq=10 ttl=64 time=0.050 ms

--- 10.0.0.2 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9036ms
rtt min/avg/max/mdev = 0.040/0.974/5.887/1.912 ms

Thanks in advance for your kind help. Not sure whether its an issue with OS paging or other thing that through out the process and reload it to the RAM.

With Best Regards
M A MOYEEN

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