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Reliability facts of IGRP

By mdl3 ·
hello, me again!
could some body give me a detail explanation on the following 3 fetures of IGRP.
What do they do and how?
1)Split Horizon
2)Poison Control
3)Hold-Down Timers
thanks guys!

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Reliability facts of IGRP

by Shanghai Sam In reply to Reliability facts of IGRP

1. Split horizon is used to prevent Loops in the Network by doing the following:

Routing Protocol RIP-1
Distance Vector Ruting Yes, Support Split Horizon,Holddown timers. Version RIP-1 does not send subnet masks.

Routing Protocol RIP-2
Distance Vector Routing Yes, support Holddown timers, split horizon and send also subnet masks.

Split Horizon:
The routing protocol advertises routes out an interface only if they where NOT learned from updates entering that interface.

Split Horizon with Poison reverse:
The routing protocol advertises all routes an interface BUT those learned earlier updates coming in that inteface are marked with Infinite distance metrics.

Holddown timers:
after knowing a route to a subnet has failed, a router waits a certain time before beliving any information coming from that subnet. The Holddown timer starts after 3 missing updates.

Trigger Updates: An update is sent immediatly rather than waiting on the update timer to expire which will thenstart the holddown timer. RIP holddown timer 180 sec or in other words 3min.

Update time for RIP versus EIGRP

RIP upate 30 sec EIGRP 60 sec.

Holddown timer 180 sec (RIP) EIGRP 280 sec

Flash (Triggered updates works for both prptocols).
Infinity metrics RIP (16) EIGRP 4.294.967.295

Hope it is valuable to you


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Reliability facts of IGRP

by mdl3 In reply to Reliability facts of IGRP

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Reliability facts of IGRP

by mdl3 In reply to Reliability facts of IGRP

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