Re: EIGRP Basic DUAL rule

Hi Steve Lyons,

  Got it and thank you very much. Also do you have comments on why only
delay is send with infinity metric and not b/w or other parameters in
the poison update.

Thanks

Regards
Anantha Subramanian Natarajan

On Sat, Aug 22, 2009 at 8:40 PM, Steve Lyons <charter21p5_at_gmail.com> wrote:

> To answer your questions. With a multi-access interface like frame relay or
> ethernet we can have multiple neighbors on a single interface. With the
> interface command ip eigrp split-horizon (the default) enabled and if we
> are receive an update from a neighbor on this interface we will not send out
> an update to other neighbors on this interface. EIGRP split horizon is a
> routing loop prevention mechanism. If we disable EIGRP split horizon then we
> allow updates received on the interface to be sent back out the interface to
> other neighbors. This is the reason why the poison reverse packet is sent
> out to all neighbors if EIGRP split horizon is disabled. The reason for the
> poison reverse to be sent when a new successor is chosen is to let the other
> routers know to not use this router as a next hop for best path.
>
> If you type the command show ip int "interface-name" you will see either
> Split horizon is enabled or disabled. This is not for EIGRP this is for RIP.
> To check if EIGRP split horizon is enable type show run interface
> "interface-name".
>
> Steve Lyons
>
> On Sat, Aug 22, 2009 at 8:04 PM, Anantha Subramanian Natarajan <
> anantha.natarajan_at_gravitant.com> wrote:
>
>> Hi All,
>>
>> I am able to understand the delay infinity value.It seems that vector
>> metric value of set to -1(minus 1) is infinity.Kinldy clarify the other
>> part of the questions.
>>
>> Thank You
>>
>> Regards
>> Anantha Subramanian Natarajan
>>
>> On Sat, Aug 22, 2009 at 6:45 PM, Anantha Subramanian Natarajan <
>> anantha.natarajan_at_gravitant.com> wrote:
>>
>> > Hi All,
>> >
>> > I was going though the "EIGRP Network Design solutions" and have
>> couple
>> > of questions based on the below lines.Kindly help me to understand the
>> same.
>> >
>> >
>> > *Basic DUAL Rules*
>> > *
>> >
>> > 1) Whenever a router chooses a new successor,it informs all its other
>> > neighbors about the new reported distance
>> >
>> > 2) Every time a router selects a successor,it sends a poison update
>> to
>> > its successor(poison reverse)
>> >
>> > 3) A poison update is sent to all neighbors on the interface through
>> > which the successor is reachable unless split-horizon is turned off,in
>> which
>> > case,it's sent to only the successor
>> >
>> > I am understanding that a posion update is a regular update with delay
>> set
>> > to infinity.What is that infinity value,is it the maximum delay value
>> which
>> > can be set on an interface (16777215 tens of microseconds)? .If that is
>> the
>> > case,why not the other parameters like bandwith is not set to maximum
>> value
>> > in the posion update.
>> >
>> > Also I am trying to undertstand,point 3 above,is the posion update
>> depends
>> > on the split-horizon enabled on the interface.
>> >
>> > Kindly clarify the above.Thanks for the assistance.
>> >
>> >
>> >
>> > Regards
>> >
>> > Anantha Subramanian Natarajan
>> >
>> >
>> >
>> >
>> > *
>> >
>> > **
>>
>>
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Received on Sat Aug 22 2009 - 22:25:24 ART