From: Salahaddin Elshekeil (salah.elshekeil@gmail.com)
Date: Sun Feb 15 2009 - 16:23:46 ARST
EIGRP Neighbor ProblemCause: Mismatched K Values
For EIGRP to establish its neighbors, the K constant value to manipulate the
EIGRP metric must be the same. In EIGRP's metric calculation, the default
for the K value is set so that only the bandwidth and the delay of the
interface are used to calculate the EIGRP metric. Many times, the network
administrator might want other interface factors, such as load and
reliability, to determine the EIGRP metric. Therefore, the K values are
changed. Because only bandwidth and delay are used in calculations, the
remaining K values are set to a value of 0 by default. However, the K values
must be the same for all the routers, or EIGRP won't establish a neighbor
relationship.
example: K1 is bandwidth and K3 is delay. when you change the K values
of Router B to all 1s from K1 to K4, while Router A retains the default
value of K1 and K3 to be 1. In this example, Router A and Router B will not
form EIGRP neighbor relationship because the K values don't match
Router A------------------ Router B
to change the K values
use this command under the eigrp process "*metric weights* *tos k1 k2 k3 k4
k5 * "
Default values:
*tos**: *0
*k1**:** *1
*k2**:* 0
*k3**:* 1
*k4**:* 0
*k5**:* 0
the metrics between the two routers should be matched so they can form
neighbor relationship
On Sun, Feb 15, 2009 at 8:52 PM, Hussam EL Kebbi
<hussamkibbi@hotmail.com>wrote:
> Actually I was working on real network environment that I don't have access
> now anymore.
>
>
>
> I am only surprised that nothing worked when neighbors were flapping unless
> when I put MTU equal to each others!!!
>
>
>
> Does it have to do with LMI can't be fragmented or something? any idea?
>
>
>
> The output error was (K-values mismtach).
>
>
>
> > Date: Sun, 15 Feb 2009 10:44:12 -0500
> > Subject: Re: EIGRP Neighbors Flapping b/c of mismatch MTU ?
> > From: all.from.nj@gmail.com
> > To: hussamkibbi@hotmail.com
> > CC: ccielab@groupstudy.com
> >
> > A quick lab test:
> >
> > %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 1.1.1.1 (Serial0/0.1) is
> down:
> > Insufficient MTU
> >
> > R3(config-if)#do sho debug
> > IP routing:
> > IP-EIGRP Neighbor Target Events debugging is on
> > IP-EIGRP Route Events debugging is on
> >
> > I get this message when I tune the MTU to a very low value, but I was not
> > able to get it when the MTU were only slightly different.
> >
> > Have you progressed through the lab to a point where other configs have
> > caused problems? For EIGRP, slightly different MTU sizes should not
> matter
> > much in the lab type environment.
> >
> > Any additional insight to what your configs look like might help / be fun
> > for those of us wanting to lab test this along with you. I will be out
> for
> > most of the day ... going snowboarding! ;-)
> >
> > andrew>
> > andrew>en
> > andrew#
> > andrew# config brain
> > andrew(wacky brain)# go snowboarding today
> >
> > Andrew Lee Lissitz
> >
> >
> >
> > On Sun, Feb 15, 2009 at 5:17 AM, Hussam EL Kebbi
> <hussamkibbi@hotmail.com>wrote:
> >
> > > Hi Experts,
> > >
> > >
> > >
> > > I was working on a lab (EIGRP over Frame Relay) and I noticed that when
> MTU
> > > is
> > > different between neighbors
> > >
> > > it starts flapping, but when I changed MTU to same on both neighbor
> > > interfaces, it works just fine.
> > >
> > >
> > >
> > > Any idea why?
> > >
> > >
> > >
> > >
> > >
> > > Thank You,
> > >
> > > Hussam
> > >
> > >
> > >
> > >
> > >
> > > _________________________________________________________________
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> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> > --
> > Andrew Lee Lissitz
> > all.from.nj@gmail.com
> >
> >
> > Blogs and organic groups at http://www.ccie.net
> >
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> >
> >
> >
> >
> >
>
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