Q: How can I determine these Serial interface errors?

Hi, Is it a bad interface (the cable tests OK)? I have tested this interface with other routers and I get similar results. Where can I get some info on the interpretation of the debugs?

Thanks in advance, V

Some output below:

******************************** SanJose1#sh ip int brief Interface IP-Address OK? Method Status Protocol BRI0 unassigned YES not set administratively down down Ethernet0 10.0.0.12 YES NVRAM up up Loopback0 10.0.0.16 YES NVRAM up up Serial0 192.168.0.2 YES NVRAM up up Serial1 192.168.1.2 YES NVRAM administratively down down SanJose1# 0:00:37: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to down

SanJose1#debug serial int Serial network interface debugging is on SanJose1#

2:25:06: Serial0: HDLC myseq 11, mineseen 0, yourseen 12, line down 2:25:16: Serial0: HDLC myseq 12, mineseen 0, yourseen 13, line down 2:25:17: HD(0): got an interrupt state = 0x814A 2:25:17: HD(0): New serial state = 0x014A

2:25:17: HD(0): DCD is down.

2:25:17: HD(1): New serial state = 0x0600

2:25:17: HD(1): Cable is unplugged.

2:25:17: HD(0): got an interrupt state = 0x815A 2:25:17: HD(0): New serial state = 0x015F

2:25:17: HD(0): DCD is up.

2:25:17: HD(1): New serial state = 0x0600

2:25:17: HD(1): Cable is unplugged.

2:25:17: Serial0: attempting to restart 2:25:17: HD(0): Reset from 0x3023FD8 2:25:26: Serial0: HDLC myseq 13, mineseen 0, yourseen 14, line down 2:25:36: Serial0: HDLC myseq 14, mineseen 0, yourseen 15, line down 2:25:46: Serial0: HDLC myseq 15, mineseen 0, yourseen 16, line down 2:25:47: HD(0): got an interrupt state = 0x814F 2:25:47: HD(0): New serial state = 0x014A

2:25:47: HD(0): DCD is down.

2:25:47: HD(1): New serial state = 0x0600

2:25:47: HD(1): Cable is unplugged.

2:25:47: HD(0): got an interrupt state = 0x815A 2:25:47: HD(0): New serial state = 0x015F

2:25:47: HD(0): DCD is up.

2:25:47: HD(1): New serial state = 0x0600

2:25:47: HD(1): Cable is unplugged.

2:25:47: Serial0: attempting to restart 2:25:47: HD(0): Reset from 0x3023FD8 2:25:56: Serial0: HDLC myseq 16, mineseen 0, yourseen 17, line down 2:26:06: Serial0: HDLC myseq 17, mineseen 0, yourseen 18, line down 2:26:16: Serial0: HDLC myseq 18, mineseen 0, yourseen 19, line down 2:26:17: HD(0): got an interrupt state = 0x814A 2:26:17: HD(0): New serial state = 0x014A

2:26:17: HD(0): DCD is down.

2:26:17: HD(1): New serial state = 0x0600

2:26:17: HD(1): Cable is unplugged.

2:26:17: HD(0): got an interrupt state = 0x815A 2:26:17: HD(0): New serial state = 0x015F

2:26:17: HD(0): DCD is up.

2:26:17: HD(1): New serial state = 0x0600

2:26:17: HD(1): Cable is unplugged.

2:26:17: Serial0: attempting to restart 2:26:17: HD(0): Reset from 0x3023FD8 2:26:26: Serial0: HDLC myseq 19, mineseen 0, yourseen 20, line down 2:26:36: Serial0: HDLC myseq 20, mineseen 0, yourseen 21, line down 2:26:46: Serial0: HDLC myseq 21, mineseen 0, yourseen 22, line down 2:26:47: HD(0): got an interrupt state = 0x814F 2:26:47: HD(0): New serial state = 0x014A

2:26:47: HD(0): DCD is down.

2:26:47: HD(1): New serial state = 0x0600

2:26:47: HD(1): Cable is unplugged.

2:26:47: HD(0): got an interrupt state = 0x815A 2:26:47: HD(0): New serial state = 0x015F

2:26:47: HD(0): DCD is up.

2:26:47: HD(1): New serial state = 0x0600

2:26:47: HD(1): Cable is unplugged.

2:26:47: Serial0: attempting to restart 2:26:47: HD(0): Reset from 0x3023FD8 2:26:56: Serial0: HDLC myseq 22, mineseen 0, yourseen 23, line down 2:27:06: Serial0: HDLC myseq 23, mineseen 0, yourseen 24, line down 2:27:16: Serial0: HDLC myseq 24, mineseen 0, yourseen 25, line down 2:27:17: HD(0): got an interrupt state = 0x814F 2:27:17: HD(0): New serial state = 0x014A

2:27:17: HD(0): DCD is down.

2:27:17: HD(1): New serial state = 0x0600

2:27:17: HD(1): Cable is unplugged.

2:27:17: HD(0): got an interrupt state = 0x815A 2:27:17: HD(0): New serial state = 0x015F

2:27:17: HD(0): DCD is up.

2:27:17: HD(1): New serial state = 0x0600

2:27:17: HD(1): Cable is unplugged.

2:27:17: Serial0: attempting to restart 2:27:17: HD(0): Reset from 0x3023FD8 2:27:26: Serial0: HDLC myseq 25, mineseen 0, yourseen 26, line down 2:27:36: Serial0: HDLC myseq 26, mineseen 0, yourseen 27, line down 2:27:46: Serial0: HDLC myseq 27, mineseen 0, yourseen 28, line down 2:27:47: HD(0): got an interrupt state = 0x814A 2:27:47: HD(0): New serial state = 0x014A

2:27:47: HD(0): DCD is down.

2:27:47: HD(1): New serial state = 0x0600

2:27:47: HD(1): Cable is unplugged.

2:27:47: HD(0): got an interrupt state = 0x815A 2:27:47: HD(0): New serial state = 0x015F

2:27:47: HD(0): DCD is up.

2:27:47: HD(1): New serial state = 0x0600

2:27:47: HD(1): Cable is unplugged.

2:27:47: Serial0: attempting to restart 2:27:47: HD(0): Reset from 0x3023FD8 2:27:56: Serial0: HDLC myseq 28, mineseen 0, yourseen 29, line down 2:28:06: Serial0: HDLC myseq 29, mineseen 0, yourseen 30, line down 2:28:16: Serial0: HDLC myseq 30, mineseen 0, yourseen 31, line down 2:28:17: HD(0): got an interrupt state = 0x814F 2:28:17: HD(0): New serial state = 0x014A

2:28:17: HD(0): DCD is down.

2:28:17: HD(1): New serial state = 0x0600

2:28:17: HD(1): Cable is unplugged.

2:28:17: HD(0): got an interrupt state = 0x815A 2:28:17: HD(0): New serial state = 0x015F

2:28:17: HD(0): DCD is up.

2:28:17: HD(1): New serial state = 0x0600

2:28:17: HD(1): Cable is unplugged.

2:28:17: Serial0: attempting to restart 2:28:17: HD(0): Reset from 0x3023FD8 2:28:26: Serial0: HDLC myseq 31, mineseen 0, yourseen 32, line down 2:28:36: Serial0: HDLC myseq 32, mineseen 0, yourseen 33, line down 2:28:46: Serial0: HDLC myseq 33, mineseen 0, yourseen 34, line down 2:28:47: HD(0): got an interrupt state = 0x814F 2:28:47: HD(0): New serial state = 0x014A

2:28:47: HD(0): DCD is down.

2:28:47: HD(1): New serial state = 0x0600

2:28:47: HD(1): Cable is unplugged.

2:28:47: HD(0): got an interrupt state = 0x815A 2:28:47: HD(0): New serial state = 0x015F

2:28:47: HD(0): DCD is up.

2:28:47: HD(1): New serial state = 0x0600

2:28:47: HD(1): Cable is unplugged.

2:28:47: Serial0: attempting to restart 2:28:47: HD(0): Reset from 0x3023FD8 2:28:56: Serial0: HDLC myseq 34, mineseen 0, yourseen 35, line down 2:29:06: Serial0: HDLC myseq 35, mineseen 0, yourseen 36, line down u all All possible debugging has been turned off SanJose1#sh int s0 Serial0 is up, line protocol is down Hardware is HD64570 Internet address is 192.168.0.2 255.255.255.0 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 0:00:01, output 0:00:01, 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 39 packets input, 1113 bytes, 0 no buffer Received 39 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 40 packets output, 1400 bytes, 0 underruns 0 output errors, 0 collisions, 14 interface resets, 0 restarts 0 output buffer failures, 0 output buffers swapped out 24 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up

SanJose1#sh cont s 0 HD unit 0, idb = 0xABC14, driver structure at 0xB00E0 buffer size 1524 HD unit 0, V.35 DTE cable cpb = 0xE2, eda = 0x4014, cda = 0x4028 RX ring with 16 entries at 0xE24000

00 bd_ptr=0x4000 pak=0x0B1DE0 ds=0xE2BC60 status=80 pak_size=22 01 bd_ptr=0x4014 pak=0x0B02C8 ds=0xE249E4 status=80 pak_size=22 02 bd_ptr=0x4028 pak=0x0B0928 ds=0xE264D4 status=80 pak_size=0 03 bd_ptr=0x403C pak=0x0B0460 ds=0xE250A0 status=80 pak_size=0 04 bd_ptr=0x4050 pak=0x0B0790 ds=0xE25E18 status=80 pak_size=0 05 bd_ptr=0x4064 pak=0x0B0AC0 ds=0xE26B90 status=80 pak_size=0 06 bd_ptr=0x4078 pak=0x0B0C58 ds=0xE2724C status=80 pak_size=0 07 bd_ptr=0x408C pak=0x0B0DF0 ds=0xE27908 status=80 pak_size=0 08 bd_ptr=0x40A0 pak=0x0B0F88 ds=0xE27FC4 status=80 pak_size=0 09 bd_ptr=0x40B4 pak=0x0B1120 ds=0xE28680 status=80 pak_size=0 10 bd_ptr=0x40C8 pak=0x0B12B8 ds=0xE28D3C status=80 pak_size=0 11 bd_ptr=0x40DC pak=0x0B1450 ds=0xE293F8 status=80 pak_size=0 12 bd_ptr=0x40F0 pak=0x0B15E8 ds=0xE29AB4 status=80 pak_size=0 13 bd_ptr=0x4104 pak=0x0B1780 ds=0xE2A170 status=80 pak_size=0 14 bd_ptr=0x4118 pak=0x0B1918 ds=0xE2A82C status=80 pak_size=0 15 bd_ptr=0x412C pak=0x0B1AB0 ds=0xE2AEE8 status=80 pak_size=0 16 bd_ptr=0x4140 pak=0x0B1C48 ds=0xE2B5A4 status=80 pak_size=0 cpb = 0xE2, eda = 0x4828, cda = 0x4828 TX ring with 4 entries at 0xE24800 00 bd_ptr=0x4800 pak=0x000000 ds=0xE0007C status=80 pak_size=22 01 bd_ptr=0x4814 pak=0x000000 ds=0xE0007C status=80 pak_size=22 02 bd_ptr=0x4828 pak=0x000000 ds=0x000000 status=80 pak_size=0 03 bd_ptr=0x483C pak=0x000000 ds=0x000000 status=80 pak_size=0 04 bd_ptr=0x4850 pak=0x000000 ds=0x000000 status=80 pak_size=0 0 missed datagrams, 0 overruns 0 bad datagram encapsulations, 0 memory errors 0 transmitter underruns

SanJose1#

The other router details:

****************** Router#sh int s0 Serial0 is up, line protocol is down Hardware is HD64570 Internet address is 192.168.0.1 255.255.255.0 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 0:00:08, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Output queue: 0/64/0 (size/threshold/drops) Conversations 0/1 (active/max active) Reserved Conversations 0/0 (allocated/max allocated) 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 51 packets output, 1377 bytes, 0 underruns 0 output errors, 0 collisions, 19 interface resets, 0 restarts 0 output buffer failures, 0 output buffers swapped out 33 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up Router#

Router#sh cont s 0 HD unit 0, idb = 0xAD928, driver structure at 0xB1DF0 buffer size 1524 HD unit 0, V.35 DCE cable, clockrate 56000 cpb = 0x44, eda = 0xD940, cda = 0xD800 RX ring with 16 entries at 0x44D800

00 bd_ptr=0xD800 pak=0x0B1FDC ds=0x44E1E4 status=80 pak_size=0 01 bd_ptr=0xD814 pak=0x0B2174 ds=0x44E8A0 status=80 pak_size=0 02 bd_ptr=0xD828 pak=0x0B230C ds=0x44EF5C status=80 pak_size=0 03 bd_ptr=0xD83C pak=0x0B24A4 ds=0x44F618 status=80 pak_size=0 04 bd_ptr=0xD850 pak=0x0B263C ds=0x44FCD4 status=80 pak_size=0 05 bd_ptr=0xD864 pak=0x0B27D4 ds=0x450390 status=80 pak_size=0 06 bd_ptr=0xD878 pak=0x0B296C ds=0x450A4C status=80 pak_size=0 07 bd_ptr=0xD88C pak=0x0B2B04 ds=0x451108 status=80 pak_size=0 08 bd_ptr=0xD8A0 pak=0x0B2C9C ds=0x4517C4 status=80 pak_size=0 09 bd_ptr=0xD8B4 pak=0x0B2E34 ds=0x451E80 status=80 pak_size=0 10 bd_ptr=0xD8C8 pak=0x0B2FCC ds=0x45253C status=80 pak_size=0 11 bd_ptr=0xD8DC pak=0x0B3164 ds=0x452BF8 status=80 pak_size=0 12 bd_ptr=0xD8F0 pak=0x0B32FC ds=0x4532B4 status=80 pak_size=0 13 bd_ptr=0xD904 pak=0x0B3494 ds=0x453970 status=80 pak_size=0 14 bd_ptr=0xD918 pak=0x0B362C ds=0x45402C status=80 pak_size=0 15 bd_ptr=0xD92C pak=0x0B37C4 ds=0x4546E8 status=80 pak_size=0 16 bd_ptr=0xD940 pak=0x0B395C ds=0x454DA4 status=80 pak_size=0 cpb = 0x44, eda = 0xE028, cda = 0xE028 TX ring with 2 entries at 0x44E000 00 bd_ptr=0xE000 pak=0x000000 ds=0x40007C status=80 pak_size=22 01 bd_ptr=0xE014 pak=0x000000 ds=0x40007C status=80 pak_size=22 02 bd_ptr=0xE028 pak=0x000000 ds=0x000000 status=80 pak_size=0 0 missed datagrams, 0 overruns 0 bad datagram encapsulations, 0 memory errors 0 transmitter underruns

Router#

Here's some output when I swapped the cable around. Why did the interface go up/up for a short time and then up/down?

**************************************************************************** ************** 0:00:09: %SYS-5-RESTART: System restarted -- Cisco Internetwork Operating System Software IOS (tm) 3000 Software (IGS-I-L), Version 11.0(22a), RELEASE SOFTWARE (fc1) Copyright (c) 1986-2001 by cisco Systems, Inc. Compiled Wed 07-Mar-01 18:02 by pnicosia 0:00:10: %LINK-5-CHANGED: Interface TokenRing0, changed state to administrativel y down 0:00:37: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to down 0:01:23: %LINK-3-UPDOWN: Interface Serial0, changed state to down 0:02:10: %LINK-3-UPDOWN: Interface Serial0, changed state to up 0:02:10: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to up Router>en Router#sh ip int brief Interface IP-Address OK? Method Status Protocol BRI0 unassigned YES not set administratively down down Serial0 192.168.0.1 YES NVRAM up up Serial1 192.168.2.4 YES NVRAM down down TokenRing0 unassigned YES not set administratively down down Router# 0:02:47: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to down