From: Larry Roberts (groupstudy@american-hero.com)
Date: Thu Jul 08 2004 - 01:21:56 GMT-3
Maybe Im missing something here as Im no EIGRP expert but..
Why does R3 see the metric as the same for R1's Lo as the same over both
links ?
Shouldn't the metrics be different over each of the links ?
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Jensen, Brian D.
Sent: Wednesday, July 07, 2004 10:52 PM
To: 'Tim Fletcher'; ccie2be; Sergio Jimenez Arguedas; ccielab@groupstudy.com
Subject: RE: Eigrp unequal load balancing problem
Hi Tim,
My curiosity was piqued, so I set this up in the lab:
R1 Lo = 10.1.1.1
R3 Lo = 10.3.3.3
R2 Lo = 10.2.2.2
Topology is same as original diagram, R1----R2===R3. Between R2 and R3,
band on s0/0 is set to 2mb, and s0/1 is set to 1mb on both sides.
Here are the routes from R3's perspective:
D 10.2.2.0/24 [90/7519] via 10.100.1.1, 00:00:02, Serial0/0
[90/12539] via 10.200.1.1, 00:00:02, Serial0/1
D 10.1.1.0/24 [90/183771] via 10.200.1.1, 00:00:02, Serial0/1
[90/183771] via 10.100.1.1, 00:00:02, Serial0/0
Here are the routes from R2's perspective:
D 10.1.1.0/24 [90/181771] via 10.11.0.1, 00:00:02, Serial1/1
D 10.3.3.0/24 [90/7029] via 10.100.1.2, 00:00:02, Serial0/0
[90/12049] via 10.200.1.2, 00:00:02, Serial0/1
Its the strangest thing, I get load balancing between R2 and R3 in the ratio
of 2:1, but if the traffic goes from R1 to R3, then there is no load
balancing. I have tried using the variance, and even "traffic bal" under
eigrp on both sides, and the traffic still prefers the hi bw link, or s0/0.
These results are not what I expected to see. Now I too am asking, why is
this so?
Thanks,
Brian
> -----Original Message-----
> From: nobody@groupstudy.com [SMTP:nobody@groupstudy.com] On Behalf Of Tim
> Fletcher
> Sent: Wednesday, July 07, 2004 10:01 PM
> To: ccie2be; Sergio Jimenez Arguedas; ccielab@groupstudy.com
> Subject: Re: Eigrp unequal load balancing problem
>
> At 08:33 PM 7/6/2004, ccie2be wrote:
> >OK, guys. You're not getting it, so I'll give you a hint.
> >
> >The problem is that from R3's point of view, the 2 paths to R1 are
> >equal cost. This is because when Eigrp figures out the cost to a
> >destination,
> it
> >using the lowest bandwidth link anywhere along the path to the
> destination.
> >Since the path to R1's lo0 includes a single 64k link between R2 and
> >R1, from R3's point of view both paths to R1 are equal.
>
> That's not entirely true. EIGRP does use the lowest bandwidth link in
> the path, but it also uses the cumulative delay. So you will see a
> larger difference in the metrics to reach R2 than the metrics to reach R1.
>
> From R3's perspective, the two paths to R2 are going to have
> different bandwidth and delay values, but the two paths to R1 are only
> going to have a difference in the delay value. The difference will
> also be smaller because both paths will include the 64K link which
> will have a higher delay than either of the other links. So you should
> see a difference in the metrics to R1, but it will be much smaller.
>
>
> >That, unfortunately, is as much as I know. What I don't know is how
> >to overcome this problem such that R3 unequal load balances traffic
> >to R1
> just
> >llike it does with traffic to R2.
>
> How about changing the EIGRP k values to achieve what you're after.
> One possibility is to set them to only use delay, then set the delay
> very low on the 64K link from R2 to R1. This should give you pretty
> close to the same distribution.
>
>
>
> >----- Original Message -----
> >From: "Sergio Jimenez Arguedas" <sejimenez@its.co.cr>
> >To: <ccielab@groupstudy.com>
> >Sent: Thursday, July 22, 2004 8:14 PM
> >Subject: RV: Eigrp unequal load balancing problem
> >
> >
> >> Hi,
> >>
> >> I think traffic shara balanced is the option!!!
> >>
> >>
> >http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cg
> >cr/f
> ipr
> >> rp_r/1rfeigrp.htm#wp1024898
> >>
> >>
> >> Rgds,
> >>
> >>
> >> Sergio
> >>
> >>
> >> -----Mensaje original-----
> >> De: nobody@groupstudy.com [mailto:nobody@groupstudy.com]En nombre
> >> de ccie2be Enviado el: martes, 06 de julio de 2004 17:44
> >> Para: tycampbell@comcast.net; Group Study
> >> Asunto: Re: Eigrp unequal load balancing problem
> >>
> >>
> >> Nope, not the answer.
> >>
> >> Variance is already configured and unequal load balancing already
> >> works between R2 and R3.
> >>
> >> The problem is that while unequal load balancing works between R2 &
> >> R3, unequal load balancing *doesn't* work between
> >>
> >> R1 and R3.
> >>
> >> Why?
> >>
> >> And, what is the solution?
> >>
> >>
> >> ----- Original Message -----
> >> From: <tycampbell@comcast.net>
> >> To: "ccie2be" <ccie2be@nyc.rr.com>; "Group Study"
> <ccielab@groupstudy.com>
> >> Sent: Tuesday, July 06, 2004 7:06 PM
> >> Subject: Re: Eigrp unequal load balancing problem
> >>
> >>
> >> > I think variance may be the answer you are looking for
> >> >
> >> > variance of 2 should do it for this scenario
> >> >
> >> >
> >> > > Hi guys,
> >> > >
> >> > > Here's the scenario:
> >> > >
> >> > >
> >> > > 2 mbps
> >> > > R1 -----64k ----- R2 ========= R3
> >> > > 1 mbps
> >> > >
> >> > >
> >> > > All routers are running Eigrp. R2 and R3 have unequal load
> balancing
> >> > > configured.
> >> > >
> >> > > Traffic between R2's lo0 and R3's lo0 unequal load balances
> perfectly.
> >> > > However, traffic between R1's lo0 and R3's lo0 don't unequal
> >> > > load balance. In this case, traffic is balanced equally
> across
> >> the 2
> >> > > links between R2 and R3.
> >> > >
> >> > > What the best way to have twice as much traffic going over the
> >> > > 2
> mbps
> >> link
> >> > > from R3 to R2 as the 1 mbps link between those 2 routers?
> >> > >
> >> > >
> >> > > TIA, Tim
> >> > >
> >> > >
> >_____________________________________________________________________
> >__
> >> > > Please help support GroupStudy by purchasing your study
> >> > > materials
> >from:
> >> > > http://shop.groupstudy.com
> >> > >
> >> > > Subscription information may be found at:
> >> > > http://www.groupstudy.com/list/CCIELab.html
> >>
> >> ___________________________________________________________________
> >> ____ Please help support GroupStudy by purchasing your study
> >> materials from:
> >> http://shop.groupstudy.com
> >>
> >> Subscription information may be found at:
> >> http://www.groupstudy.com/list/CCIELab.html
> >>
> >> ___________________________________________________________________
> >> ____ Please help support GroupStudy by purchasing your study
> >> materials from:
> >> http://shop.groupstudy.com
> >>
> >> Subscription information may be found at:
> >> http://www.groupstudy.com/list/CCIELab.html
> >
> >_____________________________________________________________________
> >__ Please help support GroupStudy by purchasing your study materials
> >from:
> >http://shop.groupstudy.com
> >
> >Subscription information may be found at:
> >http://www.groupstudy.com/list/CCIELab.html
>
> ______________________________________________________________________
> _ Please help support GroupStudy by purchasing your study materials
> from:
> http://shop.groupstudy.com
>
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Sun Aug 01 2004 - 10:11:49 GMT-3