I have connected a 4000 series router and a 2500 series routers serially using a back-to-back serial cable.The problem is that the line protocol never comes up.I am attaching the outputs here.Please help.
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2500 series router outputs
2500#show interfaces serial 1
Serial1 is down, line protocol is down
Hardware is HD64570
Internet address is 10.0.0.1/8
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input never, output never, output hang never
Last clearing of "show interface" counters never
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 0/0/256 (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
0 packets input, 0 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
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 39 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=down DSR=down DTR=up RTS=up CTS=up
2500#debug serial interface
Serial network interface debugging is on
2500(config)#int s 1
2500(config-if)#shut
2500(config-if)#no shut
2500(config-if)#
%LINK-3-UPDOWN: Interface Serial1, changed state to down
%LINK-3-UPDOWN: Interface Serial1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to up
2500#
Serial1: attempting to restart
HD(1): Deasserting DTR and RTS
HD(1): Reset from 0x3087208
HD(1): Asserting DTR
HD(1): Deasserting LTST
HD(1): Asserting DTR and RTS
HD(0): New serial state = 0x0600
HD(0): Cable is unplugged.
HD(1): got an interrupt state = 0x815A
HD(1): New serial state = 0x015A
HD(1): DCD is down.
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to down
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4000 series router outputs.
4000#show interfaces serial 1
Serial1 is up, line protocol is down
Hardware is HD64570
Internet address is 10.0.0.2 255.0.0.0
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input never, output 0:00:00, output hang never
Last clearing of "show interface" counters never
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
88 packets output, 3188 bytes, 0 underruns
0 output errors, 0 collisions, 27 interface resets, 0 restarts
0 output buffer failures, 0 output buffers swapped out
54 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
4000#debug serial interface
4000#
Serial1: HDLC myseq 12, mineseen 0, yourseen 0, line down
Serial1: attempting to restart
HD(1): Reset from 0x2F080
HD(1): New serial modem register = 0x019F
HD(1): DTR is up.
Serial1: HDLC myseq 13, mineseen 0, yourseen 0, line down
Serial1: HDLC myseq 14, mineseen 0, yourseen 0, line down
HD(1): New serial modem register = 0x019D
HD(1): DTR is up.
HD(1): New serial modem register = 0x0198
HD(1): DTR is down.
HD(1): New serial modem register = 0x019D
HD(1): DTR is up.
HD(1): New serial modem register = 0x019F
HD(1): DTR is up.
Serial1: HDLC myseq 15, mineseen 0, yourseen 0, line down
