OSPF LSA start throttle

[Sherif Atef Ahmed Ismail]

Dears

Would like your assistance please in confirming my understadning regarding OSPF LSA generation delay

If OSPF is configured with default values, then first router/network LSA will be delayed by 500 ms (actually not shown in commands but mentioned in documents !), and subsequent same LSAs will be delayed by 5 seconds as shown below output

As with SPF computations, we can configure LSA start throttling with command "timers throttle lsa" and this will override previous behavior

Now If I am correct, why in command reference it mentions that default values for "timers throttle lsa" is as below when this command is not enabled by default

start-interval : 0 milliseconds

hold-interval:5000 milliseconds

max-interval: 5000 milliseconds

R2(config-router)#timers throttle lsa all ?

  <0-600000>  Delay to generate first occurrence of LSA in milliseconds

R2(config-router)#timers throttle lsa all 0 ?

  <1-600000>  Minimum delay between originating the same LSA in milliseconds

R2(config-router)#timers throttle lsa all 0 50 ?

  <1-600000>  Maximum delay between originating the same LSA in milliseconds

R2(config-router)#timers throttle lsa all 0 50 60

|||||||||||||||

R2#sh ip ospf  | i sec

Initial SPF schedule delay 5000 msecs

Minimum hold time between two consecutive SPFs 10000 msecs

Maximum wait time between two consecutive SPFs 10000 msecs

Minimum LSA interval 5 secs  <<-------

Minimum LSA arrival 1000 msecs

LSA group pacing timer 240 secs

Interface flood pacing timer 33 msecs

Retransmission pacing timer 66 msecs

Thanks

Regards

Sherif Ismail

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

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Posting

What you're reading, about the 1/2 second delay, might pertain to IOS before the OSPF LSA throttle option was added as a feature.

[Sherif Atef Ahmed Ismail]

Hi Joseph

Yes thinks so but wonder why even in latest IOS command reference 15.3S it is mentioning default values when feature is not configured by default

Thanks

[Joseph W. Doherty]

Could you provide a link to what you're reading?

[Sherif Atef Ahmed Ismail]

Hi Joseph

Please check below URL

http://www.cisco.com/en/US/docs/ios-xml/ios/iproute_ospf/configuration/15-s/iro-lsa-throt.html

Appreciate your assistance

Regards

Sherif Ismail

[Joseph W. Doherty]

Ok, unless I'm missing it, I didn't see a reference to holding the first LSA for 500 ms.  By default, the first LSA is sent immediately and next LSA is held for 5 seconds.

Is the issue the shown "Minimum LSA interval 5 secs"?  If so, consider the word "interval" as in time between LSAs, which would be 5 secs, by default.

[Sherif Atef Ahmed Ismail]

Hi Joseph

mmm could be .. please check below ospf o/p before and after configuring LSA throttling

7606-1#sh ip ospf 1 | i sec

Initial SPF schedule delay 50 msecs

Minimum hold time between two consecutive SPFs 1000 msecs

Maximum wait time between two consecutive SPFs 5000 msecs

Minimum LSA interval 5 secs

Minimum LSA arrival 1000 msecs

LSA group pacing timer 240 secs

Interface flood pacing timer 33 msecs

Retransmission pacing timer 66 msecs

    restart-interval limit: 120 sec

7606-1#

7606-1#conf t

7606-1(config)#router ospf 1

7606-1(config-router)#timers throttle lsa 0 1000 5000

7606-1#sh ip ospf 1 | i sec

Initial SPF schedule delay 50 msecs

Minimum hold time between two consecutive SPFs 1000 msecs

Maximum wait time between two consecutive SPFs 5000 msecs

Initial LSA throttle delay 0 msecs

Minimum hold time for LSA throttle 1000 msecs

Maximum wait time for LSA throttle 5000 msecs

Minimum LSA arrival 1000 msecs

LSA group pacing timer 240 secs

Interface flood pacing timer 33 msecs

Retransmission pacing timer 66 msecs

    restart-interval limit: 120 sec

7606-1#

Many Thanks

Sherif Ismail

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

Hmm, that's interesting.  It appears it accepted the timers throttle command's values.  But before you used that command, I now wonder if it is default to earlier Cisco defaults.  What IOS is this?

[Sherif Atef Ahmed Ismail]

Hi Joseph

I tried it on 124-25d at GNS3 and on a 7600 using IOS 15.3S1 and both were giving same result

Also you may find below post intresrting .. Now I am finding for an answer for both topics

https://supportforums.cisco.com/message/3917690

Thanks

Regards

Sherif Ismail