Diagnose co-location networking problem

[Stephan Wehner]

Ok, this is a little unfortunate: I can't run traceroute from the client PC (the service provider doesn't seem to like it). (Nor can I use ping)

The server FreeBSD kernel doesn't support tcpdump. I should recompile it then, but not now.

So I ran the netstat tests, seeing no other suggestion. Below is the output before and after "failed" accesses. If I understand, there seems no indication of lost packets.

At least the problem is rather reproducible: run 'lynx -dump http://stbgo.org > /dev/null' in a loop, 15 times and a failure occurs. I also thought maybe the ssh session might be interfering, rather than showing a live connection; but without it the same occurs.

Thanks a lot to all for now.

Stephan

# Both on client and server:
$ netstat -i > /tmp/before
$ netstat -s | grep -i ret >> /tmp/before
  ... run test .... recognize failure ...
$ netstat -i > /tmp/after
$ netstat -s | grep -i ret >> /tmp/after

Client first.

$ cat /tmp/before
Kernel Interface table
Iface   MTU Met   RX-OK RX-ERR RX-DRP RX-OVR   TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0   1500   012471498      0      0      0 8604916     36      0      1 BMRU
eth0:  1500   0     - no statistics available -                        BMRU
eth0:  1500   0     - no statistics available -                        BMRU
lo    16436   0  429696      0      0      0  429696      0      0      0 LRU
    66656 segments retransmited
    TCPLostRetransmit: 0
    TCPFastRetrans: 1233
    TCPForwardRetrans: 18
    TCPSlowStartRetrans: 476
$ cat /tmp/after
Kernel Interface table
Iface   MTU Met   RX-OK RX-ERR RX-DRP RX-OVR   TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0   1500   012471903      0      0      0 8605107     36      0      1 BMRU
eth0:  1500   0     - no statistics available -                        BMRU
eth0:  1500   0     - no statistics available -                        BMRU
lo    16436   0  429786      0      0      0  429786      0      0      0 LRU
    66665 segments retransmited
    TCPLostRetransmit: 0
    TCPFastRetrans: 1233
    TCPForwardRetrans: 18
    TCPSlowStartRetrans: 476

Now server
$ cat /tmp/before_server
Name    Mtu Network       Address              Ipkts Ierrs    Opkts Oerrs  Coll
bge0   1500 <Link#1>      00:0b:cd:4e:40:00   156342     3   146739     0   599 
bge0   1500 65.110.18.136 df1                 144448     -   145988     -     - 
bge1*  1500 <Link#2>      00:0b:cd:4e:41:11        0     0        0     0     0 
pflog 33208 <Link#3>                               0     0        0     0     0 
lo0   16384 <Link#4>                           34545     0    34545     0     0 
lo0   16384 your-net      localhost.stephan    34454     -    34454     -     - 
pfsyn  2020 <Link#5>                               0     0        0     0     0 
                565 data packets (372083 bytes) retransmitted
                38 data packets unnecessarily retransmitted
        540 retransmit timeouts
                156 retransmitted
        0 invalid return addresses
        0 no return routes
$ cat /tmp/after_server
Name    Mtu Network       Address              Ipkts Ierrs    Opkts Oerrs  Coll
bge0   1500 <Link#1>      00:0b:cd:4e:40:00   156579     3   146957     0   599 
bge0   1500 65.110.18.136 df1                 144671     -   146206     -     - 
bge1*  1500 <Link#2>      00:0b:cd:4e:41:11        0     0        0     0     0 
pflog 33208 <Link#3>                               0     0        0     0     0 
lo0   16384 <Link#4>                           34685     0    34685     0     0 
lo0   16384 your-net      localhost.stephan    34594     -    34594     -     - 
pfsyn  2020 <Link#5>                               0     0        0     0     0 
                565 data packets (372083 bytes) retransmitted
                38 data packets unnecessarily retransmitted
        540 retransmit timeouts
                156 retransmitted
        0 invalid return addresses
        0 no return routes