thanks very much for your advice Bob, my 'sh int' entry below is showing 'link status = up', as far as I'm aware our switches didn't have any special port configuration but its something I'll need to look into (they are SRW2024s).
# sh int
Interface Statistics
Total Packets Received = 92794247
Total Bytes Received = 114114975872
Missed Packet Percentage = 0
Current Bypass Mode = Auto_off
MAC statistics from interface GigabitEthernet0/0
Interface function = Command-control interface
Description =
Media Type = TX
Default Vlan = 0
Link Status = Up
Link Speed = Auto_1000
Link Duplex = Auto_Full
Total Packets Received = 522437
Total Bytes Received = 57817209
Total Multicast Packets Received = 25448
Total Receive Errors = 0
Total Receive FIFO Overruns = 0
Total Packets Transmitted = 36
Total Bytes Transmitted = 2304
Total Transmit Errors = 0
Total Transmit FIFO Overruns = 0
MAC statistics from interface GigabitEthernet0/1
Interface function = Sensing interface
Description =
Media Type = backplane
Default Vlan = 0
Inline Mode = Unpaired
Pair Status = N/A
Hardware Bypass Capable = No
Hardware Bypass Paired = N/A
Link Status = Up
Admin Enabled Status = Enabled
Link Speed = Auto_1000
Link Duplex = Auto_Full
Missed Packet Percentage = 0
Total Packets Received = 92794255
Total Bytes Received = 114114976809
Total Multicast Packets Received = 0
Total Broadcast Packets Received = 0
Total Jumbo Packets Received = 0
Total Undersize Packets Received = 0
Total Receive Errors = 0
Total Receive FIFO Overruns = 0
Total Packets Transmitted = 92794255
Total Bytes Transmitted = 114115165919
Total Multicast Packets Transmitted = 0
Total Broadcast Packets Transmitted = 0
Total Jumbo Packets Transmitted = 0
Total Undersize Packets Transmitted = 0
Total Transmit Errors = 0
Total Transmit FIFO Overruns = 0
