Line/protocol status on switch/router

errorken

How does the line/protocol status of a router and switch change when:

- A cable on the other end is disconnected (ethernet port)
- The interface on the other end is administratively shutdown (ethernet port)

According to odom, the interface will be in down/down for both cases, on routers and switches.
Is this correct?
When I simulate the second case, in GNS between two routers, the status remains up/up.

Also, when no IP address is configured, the status remains up/up.
I assume this is normal since line/protocol is giving information about layer1/layer2 respectively?

scheistermeister

errorken wrote:

How does the line/protocol status of a router and switch change when:

- A cable on the other end is disconnected (ethernet port)
- The interface on the other end is administratively shutdown (ethernet port)

According to odom, the interface will be in down/down for both cases, on routers and switches.
Is this correct?
When I simulate the second case, in GNS between two routers, the status remains up/up.

Should be down/down

errorken wrote:

Also, when no IP address is configured, the status remains up/up.
I assume this is normal since line/protocol is giving information about layer1/layer2 respectively?

Correct.

kryolla

it will be down if it looses connectivity to the switch for ethernet. For frame relay for the main interface it will down if it looses lmi with the frame relay switch. For sub interface point to point it will be down if the DLCI in the other end is down for multipoint it will be down if ALL DLCI on the other end is down. Having connectivity with the local switch is different than having end to end keep alive and what causes the line protocol to go down thus removing the appropriate routes from the RIB.

HTH

billyr

I have always been led to believe that if you remove an ethernet cable from an active Router to Switch connection that the status would change to:

Down and Down. Down at layer 1 and 2, which of course makes sense. The same when the switch port is shutdown.

However if you lab it up you will find that as long as you have the no shut command applied to the Ethernet Router interface it will actually appear as UP Down whether a cable is connected or not.