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Re: barak-online.net icmp performance vs. traceroute/tcptraceroute, ssh, ipsec

  • From: Joe Maimon
  • Date: Mon May 07 21:42:25 2007



Lincoln Dale wrote:

Lower than 1500 mtu always requires some kind of hack in real life.

That would be the adjust-mss which is the hack-of-choice 


note that using 'adjust-mss' only adjusts the MSS for TCP.
it won't do much good for already-encapsulated IPSec traffic with protocol 47
or tunneled over UDP...

Which is why its configured on the ipsec tunnel. And if there isnt one, on the the ingress interface. Which brings forth the observation that adjust mss should rather be used in route-map pbr style.

I know we had that whole discussion right here, back when I was younger and dumber, such as here:

http://www.merit.edu/mailinglist/mailarchives/old_archive/2003-12/msg00088.html

Anyways, initial reports are that as per my advice, customer calls vendor says "voip not working" vendor says "i changed something, wont tell you what, reboot everything in 30" and now things seem to work perfectly, strangely enough EVEN the traceroutes.

This is obviously not best effort. Best guess would be "managed bandwidth" differentiated by ip ranges and that the "change" was a different pool assignment.

I suspect the stellar icmp echo performance is also intentional.

Compare:

tcptraceroute lsvomonline.dnsalias.com -q 5 -w 1 80 -f 7
Selected device eth0, address 192.168.0.3, port 33204 for outgoing packets
Tracing the path to lsvomonline.dnsalias.com (82.166.56.247) on TCP port 80 (www), 30 hops max
7 kar2-so-7-0-0.newyork.savvis.net (204.70.150.253) 45.008 ms 52.978 ms 32.404 ms 50.676 ms 33.657 ms
8 dcr3-ge-0-2-1.newyork.savvis.net (204.70.193.98) 49.037 ms 33.145 ms 48.029 ms 34.355 ms 48.453 ms
9 208.173.129.14 32.841 ms 32.669 ms 33.274 ms 31.861 ms 32.570 ms
10 barak-01814-nyk-b2.c.telia.net (213.248.83.2) 37.181 ms 32.600 ms 33.442 ms 32.696 ms 32.882 ms
11 po1-3.bk3-bb.013bk.net (212.150.232.214) 177.165 ms 175.852 ms 178.104 ms 179.217 ms 175.214 ms
12 gi2-1.bk6-gw.013bk.net (212.150.234.94) 180.923 ms 182.761 ms 179.170 ms 203.878 ms 178.905 ms
13 gi8-1.bk6-acc3.013bk.net (212.29.206.41) 174.266 ms 177.854 ms 177.198 ms 177.439 ms 176.400 ms
14 bk6-lns-3.013bk.net (212.29.206.55) 181.717 ms 176.460 ms 228.843 ms 174.942 ms 176.706 ms
15 82-166-56-247.barak-online.net (82.166.56.247) [open] 190.395 ms 188.043 ms 189.961 ms 200.064 ms 192.943 ms