Hold down concept

closetgeek

Can anyone break down the holddown concept.....

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networker050184

Can anyone read a book

davidspirovalentine

The Hold down time is what keeps new routing information from being used for a certain period of time. I think.

Morty3

Yeah hold-down timers is a route-loop prevention mechanism.

It works by keeping a network that has been stated as down in that very state for a time, I think that the defualt in RIP is 90 secs, no matter what it hears about that network.

Look at this picture.

172.16.3.0/25 goes down. All the surrounding routers consider the network unreachable by that link, but R1 does not get this update in time from R4, so it tells R4 and R2 that it can reach that network via R4. I think you can see where this is going (use link state protocols :P).

Hold-down timers stop this routing failures by saying that when they get the update that states 172.16.3.0 as down, they will not care for any other update for 90 seconds, so that the network get some time to converge.

I really hope i got it right!

mikej412

closetgeek wrote: »

Can anyone break down the holddown concept.....

What are you using to study for the CCNA?