On Fri, Aug 03, 2012 at 09:45:57PM +1000, Allan Duncan wrote:
I suggest you read this first: http://www.internode.on.net/support/faq/tech_space/mpls_traceroute/
It won't help you with your download problem, but it helps explain strange numbers when MPLS gets invovled.
well spotted. Mark might also want to try mtr rather than traceroute. It can display MPLS labels (press "u" in the curses interface or use "-e" on the command line) i usually use the --curses mode but the --report mode is more like traditional traceroute (and IMO more readable) e.g. $ mtr -e --report --report-wide download.linuxjournal.com HOST: ganesh Loss% Snt Last Avg Best Wrst StDev 1.|-- nexthop.vic.iinet.net.au 0.0% 10 14.6 14.2 13.8 14.6 0.3 2.|-- te7-2.mel-pipe-bdr1.iinet.net.au 0.0% 10 14.5 14.2 13.9 14.8 0.3 3.|-- xe-0-1-0-0.syd-ult-core1.iinet.net.au 0.0% 10 24.7 24.4 23.9 25.0 0.3 4.|-- te3-1-0.bdr1.syd7.internode.on.net 0.0% 10 23.7 23.5 22.7 24.7 0.5 5.|-- po3-0-0.bdr1.sjc2.internode.on.net 0.0% 10 205.9 205.9 205.4 206.3 0.3 6.|-- te1-7.bbr01.eq01.sjc01.networklayer.com 0.0% 10 204.8 204.2 203.7 204.8 0.4 7.|-- ae7.bbr02.eq01.sjc02.networklayer.com 0.0% 10 205.5 205.7 205.3 206.2 0.3 | +-- [MPLS: Lbl 356132 Exp 0 S 1 TTL 1] 8.|-- ae0.bbr02.cs01.lax01.networklayer.com 0.0% 10 212.5 212.8 212.4 213.2 0.3 | +-- [MPLS: Lbl 308816 Exp 0 S 1 TTL 1] 9.|-- ae7.bbr01.cs01.lax01.networklayer.com 0.0% 10 213.7 213.9 212.4 220.7 2.5 | +-- [MPLS: Lbl 567317 Exp 0 S 1 TTL 1] 10.|-- ae19.bbr01.eq01.dal03.networklayer.com 20.0% 10 241.7 241.6 241.3 242.0 0.3 11.|-- po31.dsr01.dllstx3.networklayer.com 0.0% 10 243.3 243.8 243.2 246.8 1.1 12.|-- te4-1.dsr01.dllstx2.networklayer.com 10.0% 10 241.7 243.3 241.2 254.0 4.1 | +-- [MPLS: Lbl 13666 Exp 0 S 1 TTL 1] 13.|-- te3-1.car16.dllstx6.networklayer.com 10.0% 10 244.6 244.6 244.3 245.2 0.3 14.|-- saratoga.site5.com 10.0% 10 239.8 239.9 239.6 240.5 0.3 I think Mark has mentioned problems downloading the Linux Journal before. Makes me wonder what the MTU and MRU on his PPP interface is and whether he (or Telstra) is blocking ICMP packets (in particular ICMP Fragmentation Required msgs). Mark, try setting the MTU and MRU to some fairly low value (the default of 1500 is too big for a 56K modem connection anyway). something like 600 or 900 each perhaps. and then see if the download works. IF this works, there'll be a bit more throughput loss to packet overhead (more and smaller packets) but a slightly slower download that works is better than one that doesn't :) it's been far too long since i had a modem connection, i can't remember what I used to set mine at. 600 is a good test value - if that doesn't help then MRU and MTU issues are not the source of the problem and there's no point wasting time trying to find the highest value that works reliably (just set them back to default values). If it does help then gradually increase them (in increments of 50 or 100) until the download stops working again - you have now discovered a good value for MTU and MRU for your connection. craig -- craig sanders <cas@taz.net.au>