From: Jensen, Brian D. (bdjensen@eschelon.com)
Date: Thu Jul 08 2004 - 12:32:18 GMT-3
Hi Tim,
Here they are:
R2
Serial0/0 is up, line protocol is up
Hardware is DSCC4 Serial
Internet address is 10.100.1.2/30
MTU 1500 bytes, BW 2000 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Serial0/1 is up, line protocol is up
Hardware is DSCC4 Serial
Internet address is 10.200.1.2/30
MTU 1500 bytes, BW 1000 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Serial1/1 is up, line protocol is up
Hardware is DSCC4 with integrated T1 CSU/DSU
Internet address is 10.11.0.2/30
MTU 1500 bytes, BW 56 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
R3
Serial0/0 is up, line protocol is up
Hardware is PowerQUICC Serial
Internet address is 10.100.1.1/30
MTU 1500 bytes, BW 2000 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Serial0/1 is up, line protocol is up
Hardware is PowerQUICC Serial
Internet address is 10.200.1.1/30
MTU 1500 bytes, BW 1000 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
R1
Serial1/1 is up, line protocol is up
Hardware is QUICC with integrated T1 CSU/DSU
Internet address is 10.11.0.1/30
MTU 1500 bytes, BW 56 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
I am thinking that there should be no difference between the type of
interface, like ethernet vs. serial for this problem, as the calcs should
only be on bw and delay.
Thanks,
Brian
-----Original Message-----
From: Tim Fletcher [mailto:groupstudy@fletchmail.net]
Sent: Thursday, July 08, 2004 10:08 AM
To: Jensen, Brian D.; ccie2be; Sergio Jimenez Arguedas;
ccielab@groupstudy.com
Subject: RE: Eigrp unequal load balancing problem
Brian,
Can you post the bandwidth and delay parameters from a "sh int" for each of
the interfaces involved.
-Tim Fletcher
At 11:52 PM 7/7/2004, Jensen, Brian D. wrote:
>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/ios122/122cgcr/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
> > >> > >
> > >> > >
> > >_______________________________________________________________________
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> > >>
> > >>
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