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New Member

OSPF Convergence time

Hi

 

How to measure the time in ms when the fail over occur in ospf , time to converge from the primary to the secandery

 

 

 

thanks

5 REPLIES
Super Bronze

DisclaimerThe Author of this

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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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

Well, it depends on multiple factors.  Are you asking about convergence on just a single router or the whole network?  Are the primary and secondary on the same router or different routers, etc.?

New Member

HiI Have both scenarioLink on

Hi

I Have both scenario

Link on the Primary router and Link on the Secondary router

 

Link primary and Link secondary on the same router

 

thanks

Super Bronze

DisclaimerThe Author of this

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

Ok, well on the router that the link failed, if it actually goes down, there's link debounce time, which varies, before the interface down is reported to the routing.  If the local interface doesn't go down, there's the OSPF dead time delay.

Then with Cisco's OSPF, and the IOS version, there's a configurable delay before an LSA is broadcast, there's a configurable delay before the receiving router will process the LSA, there's the time it takes to run SPF (which varies based on complexity of topology, speed of control plane processor, and options like iSPF), then there's the time for multiple routers to converge.  (NB: on some of Cisco timer's, there's additional configurable delay if there are multiple LSA within a certain amount of time.)

All of the above, together, might be under 100 ms to over 40 seconds.

PS:

With timer tuning, and fast detection of link outages, you might be able to achieve subsecond convergence.

Also if you have multiple equal cost paths, fail over can be in SONET time ranges.

New Member

Hi Joseph thanks for your

Hi Joseph

 

thanks for your reply

 

Pls can you post me a docs related to the Below input from your end

 

With timer tuning, and fast detection of link outages, you might be able to achieve subsecond convergence.

 

 

thanks

Super Bronze

DisclaimerThe Author of this

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

Search Cisco's main site for OSPF timers, specifically:

timers throttle spf

timers lsa arrival

timers throttle lsa

Also search for fast OSPF hellos and/or BFD.

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