frame seen at switchport but not forwarded

[ycae]

Hi all,

We are facing a strange issue at the moment. We have some cables which are quite long around ~80m. on both sides we connect a patch cord of 3m. So we have a total length of 86m which is within specs. When I connect a device to that cable, I can see the dhcp request on the switchport but that frame is not forwarded to the server.

Is there a reason for this behaviour? I would suspect that if the cable would be too long, I wouldn't see the frame on the switch.

Many thanks for your input.

Best regards,

Yves

[smitesh kharecha]

Hi Yves,

What are your config of switches on both sides ??

Can you share some topology and configuration of switches, so that we can give some suggestion.

One thing to be sure of is, it is not definately due to the cable length...

HTH,

Smitesh

PS: Please rate helpful posts....

[ycae]

Hi Smitesh,

The switch itself has no extra config. The port is configured as follows:

interface GigabitEthernet1/2

switchport access vlan dynamic

switchport mode access

no snmp trap link-status

network-policy 30

spanning-tree portfast

The network policy is as follows:

network-policy profile 30
voice vlan 30
voice-signaling vlan 30

The device I try to connect is a phone. The strange thing is that we have already another phone model connected to this and everything works like a charm (Aastra DBC425). Now we want to connect a 7444ip phone and this one causes trouble. The easy assumption is that the phone has a problem but if I connect it to a shorter cable distance then it works.

By the way, the switches are 4500 chassis and OS used is IOS-XE 03.02.00.SG

Many thanks.

Yves

[ycae]

Hi all,

We asked the company who installed the cableing to verify if there are any errors. Apparently there was an error between the mass and one pair hence the signal was disturbed.

Hence there is no problem on the switch or the phone. However, I would still be interested to know why I could see the frame on the switch port but that frame never reached the server. Be aware that this situation is not present since we have fixed the cable issue. Hence it seems that the switch detected the faulty connection?

Thanks,

Yves