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serial link interface ( serial and protocol both up) but CTS= down


Hi all,

can any body help us regarding serial link problem

serial link detals are as follows

Serial0/0/1 is up, line protocol is up

Hardware is GT96K Serial

Description: **** NAGPUR AOB_DC TO MUMBAI COB RIL Link 6 ***

Internet address is

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, LCP Open

Listen: CDPCP

Open: IPCP, loopback not set

Keepalive set (10 sec)

Last input 00:32:20, output 00:00:00, output hang never

Last clearing of "show interface" counters 00:52:04

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/2/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 1158 kilobits/sec

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

1337 packets input, 1509392 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

1337 packets output, 1509392 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=down

here in last raw CTS is down === is their any problem with the CTS is showing down....

1 Reply 1


What kind of router is this?

Are you using an internal CSU/DSU or external?

Typically, the CTS (clear-to-send) signal is generated by the DCE (CSU/DSU, modem, etc) as a response to the DTE's RTS (request-to-send). After the DCE detects carrier and waits a few milliseconds for it to stabilize, it will send the CTS signal to the DTE.

Your CTS should be "up."

Is this interface passing traffic?

Whats on the distant end and can you ping it?


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