Zyndarius |
06-13-2010 09:58 AM |
Why RTTs of unicast are different to the RTTs of broadcast?
Greetings.
I was recently "playing" with ping in order to measure some RTT both in unicast and broadcast cases but ran into something that left me like O.o wtf!
Here is the output of a ping to a private host in my LAN, a normal unicast case:
Code:
64 bytes from 192.168.2.3: icmp_seq=1 ttl=64 time=0.617 ms
64 bytes from 192.168.2.3: icmp_seq=2 ttl=64 time=1.27 ms
64 bytes from 192.168.2.3: icmp_seq=3 ttl=64 time=0.595 ms
64 bytes from 192.168.2.3: icmp_seq=4 ttl=64 time=2.22 ms
64 bytes from 192.168.2.3: icmp_seq=5 ttl=64 time=0.654 ms
64 bytes from 192.168.2.3: icmp_seq=6 ttl=64 time=0.630 ms
And here is the sudo ping -b 255.255.255.255 with the answers of the same host as in the unicast case:
Code:
64 bytes from 192.168.2.3: icmp_seq=1 ttl=64 time=1.87 ms
64 bytes from 192.168.2.3: icmp_seq=2 ttl=64 time=66.5 ms
64 bytes from 192.168.2.3: icmp_seq=3 ttl=64 time=88.9 ms
64 bytes from 192.168.2.3: icmp_seq=4 ttl=64 time=1.88 ms
64 bytes from 192.168.2.3: icmp_seq=5 ttl=64 time=1.89 ms
64 bytes from 192.168.2.3: icmp_seq=6 ttl=64 time=53.5 ms
Can somebody explain me why do those ugly numbers appear? Is there a different process that ping uses to calculate RTTs in the case of a broadcast. As far as i know the RTTs to a host should be more or less equal either in unicast or broadcast case.
Is something I am forgetting here?
Thanks in advance for your help. =)
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