Forum - Slow routing to some servers for subnet :: SixXS

Slow routing to some servers for subnet

Shadow Hawkins on Monday, 25 October 2004 20:12:13

I have a FreeBSD 5.2 router with a tunnel to Scarlet and a subnet with other FreeBSD machines on it, and this used to work perfectly, but lately I have had some problems with routing from machines on the subnet to some networks, for example Heanet and wikipedia. Here I get very slow transfers and lots of packet loss. Other servers, like noc.sixxs.net or www.kame.net work perfectly. On the router this problem does not appear, not even when using an address in my subnet. Pinging one of the networks I have problem communicating with usually results in loss of the first few packets, and then normal pingin, until I make a connection to the server, when the replies become intermittent. Since the problem doesn't affect connections from my router this is probably a problem with the router itself, but I am at a loss as to what it could be. I have a hard time reading tcpdumps, but I have included the start of a connection to www.heanet.ie in case it should provide some clues:

20:01:11.767967 rakka.akurossu.dk.53589 > 2001:770:18:2::c101:db4f.http: S 4264408952:4264408952(0) win 65535 <mss 1440,nop,nop,sackOK,nop,wscale 1,nop,nop,timestamp 322206 0> [flowlabel 0xc276] 20:01:11.981608 2001:770:18:2::c101:db4f.http > rakka.akurossu.dk.53589: S 227843550:227843550(0) ack 4264408953 win 5712 <mss 1440,sackOK,timestamp 3400535019 322206,nop,wscale 7> 20:01:11.982118 rakka.akurossu.dk.53589 > 2001:770:18:2::c101:db4f.http: . ack 1 win 32844 <nop,nop,timestamp 322227 3400535019> [flowlabel 0xc276] 20:01:11.982491 rakka.akurossu.dk.53589 > 2001:770:18:2::c101:db4f.http: P 1:394(393) ack 1 win 32844 <nop,nop,timestamp 322227 3400535019> [flowlabel 0xc276] 20:01:12.167951 2001:770:18:2::c101:db4f.http > rakka.akurossu.dk.53589: . ack 394 win 53 <nop,nop,timestamp 3400535210 322227> 20:01:20.816636 2001:770:18:2::c101:db4f.http > rakka.akurossu.dk.53589: . 1:1209(1208) ack 394 win 53 <nop,nop,timestamp 3400543856 322227> 20:01:20.914840 rakka.akurossu.dk.53589 > 2001:770:18:2::c101:db4f.http: . ack 1209 win 32844 <nop,nop,timestamp 323121 3400543856> [flowlabel 0xc276] 20:01:21.157820 2001:770:18:2::c101:db4f.http > rakka.akurossu.dk.53589: . 1209:1429(220) ack 394 win 53 <nop,nop,timestamp 3400544203 323121> 20:01:21.254823 rakka.akurossu.dk.53589 > 2001:770:18:2::c101:db4f.http: . ack 1429 win 32844 <nop,nop,timestamp 323155 3400544203> [flowlabel 0xc276]

Relevant part of the routing table:

Destination Gateway Flags Netif Expire :: localhost UGRS lo0 => default gw-517.ams-04.nl.s UGS gif0 localhost localhost UH lo0 ::ffff:0.0.0.0 localhost UGRS lo0 gw-517.ams-04.nl.s cl-517.ams-04.nl.s UH gif0 cl-517.ams-04.nl.s link#5 UHL lo0 2001:960:6a8:: link#2 UC vr0 rakka.akurossu.dk 00:0c:6e:86:a1:b3 UHLW vr0

Any ideas?

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