Line protocol is down

joe48184

R1 serial1- Interface is up protocol is down.
R2 serial0/1 - Interface and protocol are both up.

R1 serial1 - Interface and protocol are both up.
R3 serial0/1 - Interface and protocol are both up.

Hmm... Cable is secure, Encapsulation is a match, clock is set.

Scratch head... double check everything.. Go back to basics.
Try a diferent cable between R1 and R2. DOH!!!!!

bad cable, was a fun 45 minutes...lol

Had to share that.

laidbackfreak

joe48184 wrote: »

Scratch head... double check everything.. Go back to basics.
Try a diferent cable between R1 and R2. DOH!!!!!

bad cable, was a fun 45 minutes...lol

Always start with the basics
but tis all fun learning

mmartinez85

Wouldn't a line protocol being down indicate something wrong with the data-link layer? In this case, the interface is up which further signifies that the cable is good. Why would changing the cable in this case have fixed the issue?

Can we just attribute it to the fact that the errors that systems output don't always lead us in the right direction?

joe48184

mmartinez85 wrote: »

Wouldn't a line protocol being down indicate something wrong with the data-link layer? In this case, the interface is up which further signifies that the cable is good. Why would changing the cable in this case have fixed the issue?

Can we just attribute it to the fact that the errors that systems output don't always lead us in the right direction?

With my limited knowledge I ruled out the logical.. that just left physical. On a simple serial to serial connection, I had set R1 as the DCE on serial1 and serial0. Both R1 interfaces have identical settings other than IP address and R3 could talk to R1's serial0. R2's Serial0/1 and line protocol were both up, so the problem had to be with R1 - serial1. Other than clock rate and encapsulation on a simple serial connection I couldn't think of anything else to check, so I went back to basics. I had another DTE/DCE cable handy and when I plugged it in, R1 - serial1 line protocol came up.

I just hadn't expected a cable to be bad, the pin-outs look good with no visable marks on the outside of the cable.

ThunderPipe

I had one of my techs call me to check the switch for a particular port. She had a computer that had link lights, but no connection. Hmmm...the port shows up down....Lights??? How? Weird. I go over and checking a few things realize that the user has a VOIP phone with the line going to the phone and from the phone to the PC. BIG OL' LETTERS on the phone saying DISCONNECTED. The PC got LINK LIGHTS because it was connected through the phone just fine. The phone was disconnected from the wall.