[sclug] Bizarre IMAP problem

[David Kerrawn sclug]

> -----Original Message-----
> From: sclug-bounces at sclug.org.uk [mailto:sclug-bounces at sclug.org.uk]On
> Behalf Of Darren Davison
> Sent: 26 August 2005 08:57
> To: Roland Turner (SCLUG)
> Cc: sclug at sclug.org.uk
> Subject: Re: [sclug] Bizarre IMAP problem
> 
> 
> For completeness, here's the current ifconfig for the wired 
> interface.. note
> the number of dropped packets which looks suspicious to me (quite a high
> ratio)
> 
> laptop ~ # ifconfig eth0
> eth0      Link encap:Ethernet  HWaddr 00:0F:1F:**:**:**
>           inet addr:000.000.000.31  Bcast:000.000.000.255  
> Mask:255.255.255.0
>           UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1356  Metric:1
>           RX packets:3297 errors:0 dropped:41 overruns:0 frame:25150
>           TX packets:2655 errors:0 dropped:0 overruns:0 carrier:6
>           collisions:15 txqueuelen:1000
>           RX bytes:657239 (641.8 Kb)  TX bytes:303072 (295.9 Kb)
> 

Yikes. An example one from our system is:
eth0      Link encap:Ethernet  HWaddr 00:0E:0C:**:**:**
          inet addr:000.000.100.88  Bcast:000.000.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:343233689 errors:2 dropped:0 overruns:0 frame:1
          TX packets:372028791 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:4291134824 (3.9 GiB)  TX bytes:121069413 (115.4 MiB)
          Interrupt:10 Base address:0xc400 Memory:db000000-db020000

Your frame (alignment) errors look extremely high. 41 dropped isn't too good either.
Given you are plugged into a hub, it could be that one of the devices plugged into it has a dodgy network card, or cable.
Do you have any very long cables?
Are you using more than 3 hubs?

When we have excessive CRC/Alignment errors the HP switch recommends:
# If port x is 100Base-T, make sure the cable connectors, punch-down blocks, and patch panels connecting to that port are Category 5 or better. Verify the correctness of the installation using a Category 5 test device.
# Check the directly-connected device for mismatches in half/full duplex operation (half duplex on the switch and full duplex on the connected device, or the reverse).
# Update the NIC driver software.
# Verify that the network topology conforms to IEEE 802.3 standards.
# Replace or relocate the cable. Also check the wiring closet components, transceivers, and NICs for proper operation

Regards
Davek.