Sebastian Moeller <[email protected]> writes: > Honestly, I think the best thing to do is not so much assume ATM or > lack of ATM, but simply measure it :)
Right, doing the ping test with payload sizes from 16 to 113 packets gives me an almost completely flat ping time distribution ranging from 20.3 to 21.3 ms (see attached graphic). So probably I'm on PTM... > Easy to figure out empirically by hand, by finding the largest ping > packet size that still passes without fragmentation (see > http://www.debian.org/doc/manuals/debian-reference/ch05.en.html#_finding_optimal_mtu) $ ping -c 1 -s $((1500-28)) -M do www.debian.org PING www.debian.org (128.31.0.51) 1472(1500) bytes of data. 1480 bytes from senfl.debian.org (128.31.0.51): icmp_seq=1 ttl=45 time=114 ms --- www.debian.org ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 114.522/114.522/114.522/0.000 ms $ ping -c 1 -s $((1500-27)) -M do www.debian.org PING www.debian.org (128.31.0.51) 1473(1501) bytes of data. From 10.42.3.5 icmp_seq=1 Frag needed and DF set (mtu = 1500) --- www.debian.org ping statistics --- 0 packets transmitted, 0 received, +1 errors So the MTU seems to be 1500 bytes. Now, how do I figure out what the PTM overhead is and feed it to HTB? :) -Toke
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