2811 Router fa port won't negotiate at 100mb full duplex

Here's an odd one for you.

We've just moved our routing from a layer 3 switch to a 2811. A WAN link from our provider is served via ethernet termination from the demarcation equipment.

On the old setup (using the L3 switch) the port was configured to operate at 100mb/full. However applying the same settings to the 2811 leads to it not going into the 'up' state, in fact the port refuses to acknowledge there is any connectivity.

The only way I can get the 2811 to 'see' the WAN is to run it via a basic old switch which is less than ideal.

I have applied the relevant commands to manually set the speed and duplexing on the 2811 fa port.

Any ideas?

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Comments

tech-airman

hommedepoire wrote:

Here's an odd one for you.

We've just moved our routing from a layer 3 switch to a 2811. A WAN link from our provider is served via ethernet termination from the demarcation equipment.

On the old setup (using the L3 switch) the port was configured to operate at 100mb/full. However applying the same settings to the 2811 leads to it not going into the 'up' state, in fact the port refuses to acknowledge there is any connectivity.

The only way I can get the 2811 to 'see' the WAN is to run it via a basic old switch which is less than ideal.

I have applied the relevant commands to manually set the speed and duplexing on the 2811 fa port.

Any ideas?

hommedepoire,

Questions:

What make and model was the Layer 3 Switch?
Was the physical port on the Layer 3 switch that lead to the WAN Ethernet cable configured as a switch port or a router port?
What type of customer premises equipment is the demarcation equipment?
What kind of cable are you using to connect the "Service Provider WAN Link Ethernet" to your 2811 router?
Which physical port on the 2811 are you plugging in the ethernet cable between the "WAN Link Ethernet device" from the Service Provider?
Does the 2811 have a VLAN capable built in switch?

dtlokee

If you're using the same cable you had before between the Demarc and the switch you most likely need to change it to the other type (if it was a cross over it needs to be straight through or vice versa). The L3 switch port acts like any old regular switchport with regards to MDI-X. The router acts like a host port and depending on the demarc interface type (I'm guessing MDI and the router is MDI) most likely needs a cross over cable to get an active link

HTH