[c-nsp] EIGRP reality check

[Jeff Kell]

Actually, I would have entertained "equal cost" even without the unequal
"variance" options, but the latter would be even better.

To answer some other questions others have asked... back to the original
diagram...


+--A-\
|  |  \
|  B---D
|  |  /
+--C-/

These are "layer-2" paths.  We have a rather unusual network topology
that would take too long to explain without sounding like a raving
lunatic :)  Which still may be the case, but doesn't help :)  

There are three layer-3 backbone "rings" in play here...  A-B-C-D is on
one common /22 subnet.  B-D-others are on another.  And C-D-others are
on a third.  

>From the perspective of "D" there are three paths to "B", each one
layer-3 hop away (same /22 subnet).  

Each of the three somehow works out to equivalent EIGRP paths in
topology... despite A-D and B-D being 10G and D-C and C-A being gigabit
channels.  This I suspect is due to not using "wide" EIGRP metrics.

These are all Catalysts (6500 at A, various 3750 models at B-C-D) so
nothing new and bleeding edge here.

Jeff



On 11/26/2013 10:10 PM, Mark Tinka wrote:
> On Monday, November 25, 2013 04:55:08 AM Jeff Kell wrote:
>
>> We have been using EIGRP in the most recent generation of
>> our campus network, a choice that was largely made on
>> the fact that it could load-share across equal-cost
>> paths, and take the path of "least resistance" to the
>> target.
>
> I'm guessing you meant "unequal cost" :-).
>
> Have you seen this:
>
>
http://www.cisco.com/en/US/docs/routers/crs/software/crs_r4.3/routing/configuration/guide/b_routing_cg43xcrs_chapter_0101.html#concept_6F7168EEB2D343CCBA82BB223B311E7B
>
> I haven't tried it, so don't know if it actually does what
> it says on the tin.
>
> Anyone? Oli?
>
> Mark.