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Serial link CTS=down link UP

 

 

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ziliomarcelo at gmail

Dec 17, 2009, 10:04 AM

Post #1 of 6 (5190 views)
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Serial link CTS=down link UP

Hi,

Has anyone seen this in serial interfaces before?
Link is UP and traffic is going through, however router shows CTS=down
besides a lot CRCs/Input Errors.
It doesn't make sense to me the parameter which should advise that the link
is "ready to go" is DOWN while there is traffic on it.
Users are complaining some application are slow.

The router is a Cisco 2811 IOS 12.4(15)T10.

Router#sh int s0/1/0
Serial0/1/0 is up, line protocol is up
Hardware is GT96K Serial
MTU 1500 bytes, BW 256 Kbit/sec, DLY 20000 usec,
reliability 255/255, txload 40/255, rxload 42/255
Encapsulation FRAME-RELAY IETF, loopback not set
Keepalive set (10 sec)
CRC checking enabled
LMI enq sent 48, LMI stat recvd 48, LMI upd recvd 0, DTE LMI up
LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0
LMI DLCI 0 LMI type is ANSI Annex D frame relay DTE segmentation
inactive
FR SVC disabled, LAPF state down
Broadcast queue 0/64, broadcasts sent/dropped 7/0, interface broadcasts 0
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 00:07:55
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: dual fifo
Output queue: high size/max/dropped 0/256/0
Output queue: 0/128 (size/max)
30 second input rate 43000 bits/sec, 68 packets/sec
30 second output rate 41000 bits/sec, 78 packets/sec
34746 packets input, 2956769 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
602 input errors, 602 CRC, 433 frame, 107 overrun, 0 ignored, 323 abort
43237 packets output, 3308125 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=up DSR=up DTR=up RTS=up *CTS=down*

Thanks,
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mksmith at adhost

Dec 17, 2009, 10:18 AM

Post #2 of 6 (5105 views)
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Re: Serial link CTS=down link UP [In reply to]

> -----Original Message-----
> From: cisco-nsp-bounces [at] puck [mailto:cisco-nsp-
> bounces [at] puck] On Behalf Of Marcelo Zilio
> Sent: Thursday, December 17, 2009 10:04 AM
> To: cisco-nsp [at] puck
> Subject: [c-nsp] Serial link CTS=down link UP
>
> Hi,
>
> Has anyone seen this in serial interfaces before?
> Link is UP and traffic is going through, however router shows CTS=down
> besides a lot CRCs/Input Errors.
> It doesn't make sense to me the parameter which should advise that the
> link
> is "ready to go" is DOWN while there is traffic on it.
> Users are complaining some application are slow.
>
> The router is a Cisco 2811 IOS 12.4(15)T10.
>
> Router#sh int s0/1/0
> Serial0/1/0 is up, line protocol is up
> Hardware is GT96K Serial
> MTU 1500 bytes, BW 256 Kbit/sec, DLY 20000 usec,
> reliability 255/255, txload 40/255, rxload 42/255
> Encapsulation FRAME-RELAY IETF, loopback not set
> Keepalive set (10 sec)
> CRC checking enabled
> LMI enq sent 48, LMI stat recvd 48, LMI upd recvd 0, DTE LMI up
> LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0
> LMI DLCI 0 LMI type is ANSI Annex D frame relay DTE segmentation
> inactive
> FR SVC disabled, LAPF state down
> Broadcast queue 0/64, broadcasts sent/dropped 7/0, interface
> broadcasts 0
> Last input 00:00:00, output 00:00:00, output hang never
> Last clearing of "show interface" counters 00:07:55
> Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops:
0
> Queueing strategy: dual fifo
> Output queue: high size/max/dropped 0/256/0
> Output queue: 0/128 (size/max)
> 30 second input rate 43000 bits/sec, 68 packets/sec
> 30 second output rate 41000 bits/sec, 78 packets/sec
> 34746 packets input, 2956769 bytes, 0 no buffer
> Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
> 602 input errors, 602 CRC, 433 frame, 107 overrun, 0 ignored, 323
> abort
> 43237 packets output, 3308125 bytes, 0 underruns
> 0 output errors, 0 collisions, 0 interface resets
> 0 unknown protocol drops
> 0 output buffer failures, 0 output buffers swapped out
> 0 carrier transitions
> DCD=up DSR=up DTR=up RTS=up *CTS=down*
>
With all those errors I would say you have a physical layer problem or a
clocking issue. Perhaps the CTS is flapping between up and down and
you're catching it on the down. What happens if you debug the
interface?

Regards,

Mike
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ewitkop at gmail

Dec 17, 2009, 10:22 AM

Post #3 of 6 (5088 views)
Permalink
Re: Serial link CTS=down link UP [In reply to]

Cts is clear to send. It sounds like you have a physical problem with the
line.

On Dec 17, 2009 1:09 PM, "Marcelo Zilio" <ziliomarcelo [at] gmail> wrote:

Hi,

Has anyone seen this in serial interfaces before?
Link is UP and traffic is going through, however router shows CTS=down
besides a lot CRCs/Input Errors.
It doesn't make sense to me the parameter which should advise that the link
is "ready to go" is DOWN while there is traffic on it.
Users are complaining some application are slow.

The router is a Cisco 2811 IOS 12.4(15)T10.

Router#sh int s0/1/0
Serial0/1/0 is up, line protocol is up
Hardware is GT96K Serial
MTU 1500 bytes, BW 256 Kbit/sec, DLY 20000 usec,
reliability 255/255, txload 40/255, rxload 42/255
Encapsulation FRAME-RELAY IETF, loopback not set
Keepalive set (10 sec)
CRC checking enabled
LMI enq sent 48, LMI stat recvd 48, LMI upd recvd 0, DTE LMI up
LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0
LMI DLCI 0 LMI type is ANSI Annex D frame relay DTE segmentation
inactive
FR SVC disabled, LAPF state down
Broadcast queue 0/64, broadcasts sent/dropped 7/0, interface broadcasts 0
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 00:07:55
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: dual fifo
Output queue: high size/max/dropped 0/256/0
Output queue: 0/128 (size/max)
30 second input rate 43000 bits/sec, 68 packets/sec
30 second output rate 41000 bits/sec, 78 packets/sec
34746 packets input, 2956769 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
602 input errors, 602 CRC, 433 frame, 107 overrun, 0 ignored, 323 abort
43237 packets output, 3308125 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=up DSR=up DTR=up RTS=up *CTS=down*

Thanks,
_______________________________________________
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https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/
_______________________________________________
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emccaleb at gmail

Dec 17, 2009, 2:56 PM

Post #4 of 6 (5105 views)
Permalink
Re: Serial link CTS=down link UP [In reply to]

CTS isn't needed for synchronous serial so i thought? The only time you
would need clear to send is if you are asynchronous...or so i thought. My
impression was that those pins were not tied to anything typically. And the
wires would be tied back to DCD.

Not sure i'm correct, but logically I dont see any reason for CTS on a
synchronous interface. But by all means correct me if I'm wrong.

Ernest

On Thu, Dec 17, 2009 at 1:04 PM, Marcelo Zilio <ziliomarcelo [at] gmail>wrote:

> Hi,
>
> Has anyone seen this in serial interfaces before?
> Link is UP and traffic is going through, however router shows CTS=down
> besides a lot CRCs/Input Errors.
> It doesn't make sense to me the parameter which should advise that the link
> is "ready to go" is DOWN while there is traffic on it.
> Users are complaining some application are slow.
>
> The router is a Cisco 2811 IOS 12.4(15)T10.
>
> Router#sh int s0/1/0
> Serial0/1/0 is up, line protocol is up
> Hardware is GT96K Serial
> MTU 1500 bytes, BW 256 Kbit/sec, DLY 20000 usec,
> reliability 255/255, txload 40/255, rxload 42/255
> Encapsulation FRAME-RELAY IETF, loopback not set
> Keepalive set (10 sec)
> CRC checking enabled
> LMI enq sent 48, LMI stat recvd 48, LMI upd recvd 0, DTE LMI up
> LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0
> LMI DLCI 0 LMI type is ANSI Annex D frame relay DTE segmentation
> inactive
> FR SVC disabled, LAPF state down
> Broadcast queue 0/64, broadcasts sent/dropped 7/0, interface broadcasts 0
> Last input 00:00:00, output 00:00:00, output hang never
> Last clearing of "show interface" counters 00:07:55
> Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
> Queueing strategy: dual fifo
> Output queue: high size/max/dropped 0/256/0
> Output queue: 0/128 (size/max)
> 30 second input rate 43000 bits/sec, 68 packets/sec
> 30 second output rate 41000 bits/sec, 78 packets/sec
> 34746 packets input, 2956769 bytes, 0 no buffer
> Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
> 602 input errors, 602 CRC, 433 frame, 107 overrun, 0 ignored, 323 abort
> 43237 packets output, 3308125 bytes, 0 underruns
> 0 output errors, 0 collisions, 0 interface resets
> 0 unknown protocol drops
> 0 output buffer failures, 0 output buffers swapped out
> 0 carrier transitions
> DCD=up DSR=up DTR=up RTS=up *CTS=down*
>
> Thanks,
> _______________________________________________
> cisco-nsp mailing list cisco-nsp [at] puck
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>



--
Ernest McCaleb
_______________________________________________
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ziliomarcelo at gmail

Dec 18, 2009, 3:02 AM

Post #5 of 6 (5096 views)
Permalink
Re: Serial link CTS=down link UP [In reply to]

Hi,

Debug keeps showing the following messages. I don't think is much helpfull.

Router#debug serial interface
Router#
000083: Dec 18 08:53:17.521 BST: Serial0/1/0(out): StEnq, myseq 61, yourseen
60, DTE up
000084: Dec 18 08:53:17.533 BST: Serial0/1/0(in): Status, myseq 61, pak size
19
Router#
000085: Dec 18 08:53:27.521 BST: Serial0/1/0(out): StEnq, myseq 62, yourseen
61, DTE up
000086: Dec 18 08:53:27.537 BST: Serial0/1/0(in): Status, myseq 62, pak size
14
Router#
000087: Dec 18 08:53:37.521 BST: Serial0/1/0(out): StEnq, myseq 63, yourseen
62, DTE up
000088: Dec 18 08:53:37.537 BST: Serial0/1/0(in): Status, myseq 63, pak size
14
As far as I could see CTS is always down. It is not flapping.

I'm talking to the Service Provider guys. I'll let you know the results.
Thanks for all responses!
On Thu, Dec 17, 2009 at 4:18 PM, Michael K. Smith - Adhost <
mksmith [at] adhost> wrote:

> > -----Original Message-----
> > From: cisco-nsp-bounces [at] puck [mailto:cisco-nsp-
> > bounces [at] puck] On Behalf Of Marcelo Zilio
> > Sent: Thursday, December 17, 2009 10:04 AM
> > To: cisco-nsp [at] puck
> > Subject: [c-nsp] Serial link CTS=down link UP
> >
> > Hi,
> >
> > Has anyone seen this in serial interfaces before?
> > Link is UP and traffic is going through, however router shows CTS=down
> > besides a lot CRCs/Input Errors.
> > It doesn't make sense to me the parameter which should advise that the
> > link
> > is "ready to go" is DOWN while there is traffic on it.
> > Users are complaining some application are slow.
> >
> > The router is a Cisco 2811 IOS 12.4(15)T10.
> >
> > Router#sh int s0/1/0
> > Serial0/1/0 is up, line protocol is up
> > Hardware is GT96K Serial
> > MTU 1500 bytes, BW 256 Kbit/sec, DLY 20000 usec,
> > reliability 255/255, txload 40/255, rxload 42/255
> > Encapsulation FRAME-RELAY IETF, loopback not set
> > Keepalive set (10 sec)
> > CRC checking enabled
> > LMI enq sent 48, LMI stat recvd 48, LMI upd recvd 0, DTE LMI up
> > LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0
> > LMI DLCI 0 LMI type is ANSI Annex D frame relay DTE segmentation
> > inactive
> > FR SVC disabled, LAPF state down
> > Broadcast queue 0/64, broadcasts sent/dropped 7/0, interface
> > broadcasts 0
> > Last input 00:00:00, output 00:00:00, output hang never
> > Last clearing of "show interface" counters 00:07:55
> > Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops:
> 0
> > Queueing strategy: dual fifo
> > Output queue: high size/max/dropped 0/256/0
> > Output queue: 0/128 (size/max)
> > 30 second input rate 43000 bits/sec, 68 packets/sec
> > 30 second output rate 41000 bits/sec, 78 packets/sec
> > 34746 packets input, 2956769 bytes, 0 no buffer
> > Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
> > 602 input errors, 602 CRC, 433 frame, 107 overrun, 0 ignored, 323
> > abort
> > 43237 packets output, 3308125 bytes, 0 underruns
> > 0 output errors, 0 collisions, 0 interface resets
> > 0 unknown protocol drops
> > 0 output buffer failures, 0 output buffers swapped out
> > 0 carrier transitions
> > DCD=up DSR=up DTR=up RTS=up *CTS=down*
> >
> With all those errors I would say you have a physical layer problem or a
> clocking issue. Perhaps the CTS is flapping between up and down and
> you're catching it on the down. What happens if you debug the
> interface?
>
> Regards,
>
> Mike
>
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omar.parihuana at gmail

Dec 20, 2009, 8:06 AM

Post #6 of 6 (5076 views)
Permalink
Re: Serial link CTS=down link UP [In reply to]

I'll suggest that Provider change the CSU/DSU.... since that all signals
are not open a syncronization problem can be there...

Rgds.

On Thu, Dec 17, 2009 at 1:04 PM, Marcelo Zilio <ziliomarcelo [at] gmail>wrote:

> Hi,
>
> Has anyone seen this in serial interfaces before?
> Link is UP and traffic is going through, however router shows CTS=down
> besides a lot CRCs/Input Errors.
> It doesn't make sense to me the parameter which should advise that the link
> is "ready to go" is DOWN while there is traffic on it.
> Users are complaining some application are slow.
>
> The router is a Cisco 2811 IOS 12.4(15)T10.
>
> Router#sh int s0/1/0
> Serial0/1/0 is up, line protocol is up
> Hardware is GT96K Serial
> MTU 1500 bytes, BW 256 Kbit/sec, DLY 20000 usec,
> reliability 255/255, txload 40/255, rxload 42/255
> Encapsulation FRAME-RELAY IETF, loopback not set
> Keepalive set (10 sec)
> CRC checking enabled
> LMI enq sent 48, LMI stat recvd 48, LMI upd recvd 0, DTE LMI up
> LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0
> LMI DLCI 0 LMI type is ANSI Annex D frame relay DTE segmentation
> inactive
> FR SVC disabled, LAPF state down
> Broadcast queue 0/64, broadcasts sent/dropped 7/0, interface broadcasts 0
> Last input 00:00:00, output 00:00:00, output hang never
> Last clearing of "show interface" counters 00:07:55
> Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
> Queueing strategy: dual fifo
> Output queue: high size/max/dropped 0/256/0
> Output queue: 0/128 (size/max)
> 30 second input rate 43000 bits/sec, 68 packets/sec
> 30 second output rate 41000 bits/sec, 78 packets/sec
> 34746 packets input, 2956769 bytes, 0 no buffer
> Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
> 602 input errors, 602 CRC, 433 frame, 107 overrun, 0 ignored, 323 abort
> 43237 packets output, 3308125 bytes, 0 underruns
> 0 output errors, 0 collisions, 0 interface resets
> 0 unknown protocol drops
> 0 output buffer failures, 0 output buffers swapped out
> 0 carrier transitions
> DCD=up DSR=up DTR=up RTS=up *CTS=down*
>
> Thanks,
> _______________________________________________
> cisco-nsp mailing list cisco-nsp [at] puck
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>



--
Omar E.P.T
-----------------
Certified Networking Professionals make better Connections!
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