Debug

Unanswered Question
Oct 29th, 2004
User Badges:
  • Bronze, 100 points or more

I am having a 2600 seires router.When i telnet to this router and do some debug like Debug isdn q921 after issuing terminal monitor command, after few minutes the output vanishes and i have to telnet againg to see the output.


Help needed


Ephraim Mani


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 3.3 (3 ratings)
Loading.
Kevin Dorrell Fri, 10/29/2004 - 02:57
User Badges:
  • Green, 3000 points or more


Is the exec timeout timing out? The debug output traffic is not enough in its own to keep the telnet open. Whenever I am doing serious debugging, I do:


conf t

line vty 0 4

no exec-timeout


If you have a session timeout configured as well, you should kill that too.


Don't forget to put them back again when you have finished debugging.


Kevin Dorrell

Luxembourg


EPHRAIM MANI Fri, 10/29/2004 - 03:40
User Badges:
  • Bronze, 100 points or more

No its not configured, but i cant see the debug output after few minutes and if I close the telnet window and telnet again then i can see the output.


Ephraim

Kevin Dorrell Fri, 10/29/2004 - 04:02
User Badges:
  • Green, 3000 points or more


Ephraim,


The debug settings are global, i.e. they are not specific to that particular telnet session. That is why you can quit the telnet, start a new one, issue term mon, and re-connect to the debug. You would see the debug on the console too if that was connected.


If you cannot see anything for exec-timeout under the vty lines, then the exec-timeout is the default, which is 4 minutes if I remember right. You need to specify no exec-timeout explicitly - it will then appear in the show run.


However, there is a doubt forming in my mind .... are you saying that the debug output disappears but you still have exec control on the telnet session? If so, what if you then do show debug? Could someone else be logging in and disabling your debug?


Kevin Dorrell

Luxembourg


EPHRAIM MANI Sat, 10/30/2004 - 01:48
User Badges:
  • Bronze, 100 points or more

Yes the debug output disappears but i have the control on telnet sessionn if do show debug it shows debugging is on moreover nobody is logged in at the point of time


Ephraim

Kevin Dorrell Sat, 10/30/2004 - 05:26
User Badges:
  • Green, 3000 points or more


So when you do show debug, it lists isdn q921, but you don't see any debug lines? That seems very strange. Could it be that there is simply nothing going on with q921 at the time?


Kevin Dorrell

Luxembourg


Kevin Dorrell Sat, 10/30/2004 - 05:36
User Badges:
  • Green, 3000 points or more

Found something! I suspect it is similar to bug CSCds85771. This bug was reported on AS5300, but maybe it applies to other platforms. Which version of IOS are you running? Here is the description:


Customer does term mon, and enables some debug. For a while the debug output shows on his screen (also in the log), but after a random while for some reason the debug output does not show on the terminal anymore (still shows in the system log).


This problem can happen with any debug command.



The reference is:


http://www.cisco.com/cgi-bin/Support/Bugtool/onebug.pl?bugid=CSCds85771


So, if you log the debug to a syslog, does the syslog still show the debug?


Kevin Dorrell

Luxembourg


EPHRAIM MANI Sat, 10/30/2004 - 06:33
User Badges:
  • Bronze, 100 points or more

no i am not using syslog server for logging, i just login to the router for some testing, but the debug output disappears after 10 minutes.


Ephraim

EPHRAIM MANI Sat, 10/30/2004 - 06:11
User Badges:
  • Bronze, 100 points or more

no basically i debug Modem and debug ppp authen and i dial at the same time c can see the output of modem and ppp authencation but after some time i disconnect and connect again i can't see the output then i have to close the telnet window and relogin to the router the issue the ter moni and can see the output again


Ephraim

a.awan Sat, 10/30/2004 - 07:04
User Badges:
  • Silver, 250 points or more

It might very well be a bug like Kevin suggested. Try enabling buffered logging if you do not have a syslog server. This can be done using the logging buffered command in the global configuration mode. See if the logs show up there and not on the terminal. If that is the case then it could be an instance of the bug Kevin has mentioned.

Actions

This Discussion