Strange serial port operation

I have a 2514 router that has serial port S0 to be acting up. If I configure it to be the DCE end, the port remains in a down/down state and the other router shows the port bouncing up and down. If I make the other router the DCE end (switch cable and clock rate), both ports move to an up/up state and stay solid.

Not a big deal, because I can leave it in the configuration that works, but I'm just curious if anyone has any ideas on why one of the routers is being finicky.

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Comments

veritas_libertas

Could you paste the "sho run" ?

mgates67

Sure, nothing spectacular though. If I move the clock rate to the other router and switch the cable, all is good.

2514_bottom#sh run
00:12:15: %SYS-5-CONFIG_I: Configured from console by consoleun
Building configuration...

Current configuration : 506 bytes
!
version 12.1
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname 2514_bottom
!
!
!
!
!
!
ip subnet-zero
!
!
!
!
interface Ethernet0
no ip address
shutdown
!
interface Ethernet1
no ip address
shutdown
!
interface Serial0
ip address 10.10.1.1 255.255.255.0
no fair-queue
clockrate 1000000
!
interface Serial1
no ip address
shutdown
!
ip classless
ip http server
!
!
line con 0
line aux 0
line vty 0 4
!
end

2514_top#sh run
Building configuration...

Current configuration : 484 bytes
!
version 12.1
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname 2514_top
!
!
!
!
!
!
ip subnet-zero
!
!
!
!
interface Ethernet0
no ip address
shutdown
!
interface Ethernet1
no ip address
shutdown
!
interface Serial0
ip address 10.10.1.2 255.255.255.0
no fair-queue
!
interface Serial1
no ip address
shutdown
!
ip classless
ip http server
!
!
line con 0
line aux 0
line vty 0 4
!
end

jdballinger

Double check your cables. I had ordered a serial cable from CablesAndKits, and even though one end was labeled DCE it was actually the DTE end of the cable. I found that out after trying EVERYTHING ELSE POSSIBLE, including swapping out the WIC-2T I was using. It wasn't a big deal once I figured it out, I just corrected the labeling with a black Sharpie.

mgates67

The cable is fine, it works on the other serial port in the same router and on other routers. I'm guessing it is just a bad serial port on the router. No way to fix it either, as far as I can tell.