From: Ty (tycampbell@comcast.net)
Date: Wed Jun 16 2004 - 20:09:45 GMT-3
better now. I now understand that the metric does not necessairily have to
be equal, which I was under the impression that it had to be. Over analyzing
I guess.
I had forgotten that I had that book, I will take a look at it this evening
:-)
Thank you!!!
----- Original Message -----
From: "ccie2be" <ccie2be@nyc.rr.com>
To: <tycampbell@comcast.net>; "John Matijevic" <matijevi@bellsouth.net>
Cc: "Marvin Greenlee" <marvingreenlee@yahoo.com>; <ccielab@groupstudy.com>
Sent: Wednesday, June 16, 2004 3:48 PM
Subject: Re: eigrp variance
> Ty,
>
> Your question prompted me to double check my understanding of this topic.
> Fortunately, I happen to have an old copy of Routing TCP/IP by Jeff Doyle.
> His explanation and examples are excellent.
>
> To summerize:
>
> -The traffic-share min command causes the Cisco IOS software to divide
> traffic only among the routes with the best metric. Other routes will
remain
> in the routing table, but will receive no traffic. Configuring this
command
> with the across-interfaces keyword allows you to configure multi-interface
> load splitting on different interfaces with equal cost paths.
>
> -Use the variance # command to configure unequal load-balancing. Any
routes
> where the metric < metric of lowest cost route x variance will be added to
> the route table and will be used to the extent of it's inversely
proportion
> metric e.g. if the metric is 3 times that of the lowest cost route, it
will
> get 1/3 of the traffic. That's because, by default, the unseen command
> traffic-share balanced is configured.
>
> -If multiple routes s/b in the route table but only the best route should
be
> used, use the both variance # command and traffic-share min commands.
> Without the variance command, only the best route will be in the route
> table.
>
>
> HTH
> ----- Original Message -----
> From: <tycampbell@comcast.net>
> To: "John Matijevic" <matijevi@bellsouth.net>
> Cc: "Marvin Greenlee" <marvingreenlee@yahoo.com>; <ccielab@groupstudy.com>
> Sent: Wednesday, June 16, 2004 4:28 PM
> Subject: Re: eigrp variance
>
>
> > Thanks John...sometimes the frustration of the day gets to me..as I sure
> it does to all of us, when you have to follow behind and clean some messes
> up...if you know what I mean.....arrggh...hahahah...but I still love my
> job...just a bad day...glad it doesn't happen very often...if you know
what
> I mean...and I apologize...
> >
> > I did find the article helpful, but I am still having an issue fully
> understanding the concept...it looks very simple...and I am most likely
not
> thinking on those terms
> >
> > ok...
> >
> > here's what I am having a hard time grasping..
> > going on the example of the article....
> >
> > router with metric of 20
> > router with metric of 30
> >
> > variance is set to 40.... 2*20 = 40 ok...I'm good so far...
> >
> > then the variance is 2....shouldn't it be 3, as 2*20 = 60, which is also
> divisible by 30 ?
> >
> > now that the metric of the 20 is set to 40...wouldn't the one with the
> metric of 30 be preferred...I guess I am looking at this from a
perspective
> of the metrics need to match for each route in order to be balance
> properly...I though asking for a formula may help me understand this
better,
> but I still don't see the metrics being the same for each route...that is
> what is confusing me...any insight into this would be greatly
appreciated...
> >
> >
> > > Hello Ty,
> > > I apologize if I offended you. I wasnt saying that you didnt do any
> > > research, I was just making a general observation.
> > > Again, my sincere apologies, this is a great forum, with very good
> > > engineers, we can all try and make this a better place. I hope you
find
> the
> > > article I provided you as well to be helpful.
> > > Sincerely,
> > > Matijevic
> > > ----- Original Message -----
> > > From: <tycampbell@comcast.net>
> > > To: "John Matijevic" <matijevi@bellsouth.net>
> > > Cc: "Marvin Greenlee" <marvingreenlee@yahoo.com>;
> <ccielab@groupstudy.com>
> > > Sent: Wednesday, June 16, 2004 8:37 AM
> > > Subject: Re: eigrp variance
> > >
> > >
> > > > John,
> > > >
> > > > I wasn't trying to be lazy or anything, I do searches for everything
> > > before posting a question, when I don't fully understand something
from
> the
> > > documentation. I did research, before I posted the question. We all
> learn
> > > from asking questions. If the purpose of the forum is to not ask
> questions
> > > and learn about something we don't understand, then I will refrain
from
> > > doing so. However, as I stated before, I am fully aware of doing a
> search,
> > > which I have already done. That is why the question was posted. My
very
> > > first search was actually done on the DOC CD under eigrp. I did not
> fiind
> > > anything on the DOC CD that under eigrp that even stated anything
about
> > > variance. It wasn't my last search however. By your response, you are
> > > stating that I did not do that, without even asking me first. Once
> again,
> > > the only reason I posted the question was to try to get more
> understanding
> > > about it. I didn't post the question looking for an easy way out. aA
> few
> > > people responded...it gave me bet!
> > > > ter insight to this, and I understand it better now, and I
appreciate
> > > their response.
> > > >
> > > > Ty
> > > >
> > > >
> > > > > Ty,
> > > > > The answer to your question can be done by doing a simple search.
> Let me
> > > > > explain how to do this. First you go to www.cisco.com/support, or
an
> > > archive
> > > > > or google, etc., Next, in the search box type variance, next you
> will
> > > see
> > > > > seeveral articles or messages pop up, if there are too many you
can
> try
> > > and
> > > > > use a more descriptive search or try to be more specific in your
> search.
> > > If
> > > > > there are not as many articles or messages, then you maybe too
> specific
> > > and
> > > > > have to be general in your search. Sometimes you have to use more
> than
> > > one
> > > > > resource, sometimes you have to experiment with different words,
> etc.
> > > For
> > > > > the question you had I simply went to www.cisco.com/support, then
I
> > > typed in
> > > > > variance in the search box. Then I read the following article
which
> > > > > describes the function of the command. Finally, I am not trying
to
> > > insult
> > > > > intelegence here but merely pointing out a method that has worked
> for
> > > me. I
> > > > > have observed many times that people do not search the archives or
> do
> > > proper
> > > > > research before posting. Sure its easier to post the question
then
> to
> > > do
> > > > > the research yourself. But you will become a better engineer by
> finding
> > > the
> > > > > answer yourself. At least try to make an effort. Maybe I have so
> much
> > > time
> > > > > now that I am not working that I can support this forum, and try
and
> > > make
> > > > > this a better place for everyone. I hope nobody takes offense to
> this
> > > post,
> > > > > but uses this as constructive feedback.
> > > > > Here is the article:
> > > > >
> > >
>
http://www.cisco.com/en/US/tech/tk365/tk207/technologies_tech_note09186a0080
> > > > > 09437d.shtml
> > > > >
> > > > > Sincerely,
> > > > > Matijevic
> > > > > ----- Original Message -----
> > > > > From: "Ty" <tycampbell@comcast.net>
> > > > > To: "Marvin Greenlee" <marvingreenlee@yahoo.com>
> > > > > Cc: <ccielab@groupstudy.com>
> > > > > Sent: Wednesday, June 16, 2004 3:26 AM
> > > > > Subject: Re: eigrp variance
> > > > >
> > > > >
> > > > > > Thanks Marvin!
> > > > > > ----- Original Message -----
> > > > > > From: "Marvin Greenlee" <marvingreenlee@yahoo.com>
> > > > > > To: "Ty" <tycampbell@comcast.net>
> > > > > > Cc: <ccielab@groupstudy.com>
> > > > > > Sent: Tuesday, June 15, 2004 9:58 PM
> > > > > > Subject: Re: eigrp variance
> > > > > >
> > > > > >
> > > > > > > Divide the larger metric path by the smaller metric
> > > > > > > path.
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > The variance command is related to the eigrp metric
> > > > > > > calculation.
> > > > > > >
> > > > > > > "...If k5 equals 0, the composite IGRP or EIGRP metric
> > > > > > > is computed according to the following formula:
> > > > > > >
> > > > > > > metric = [k1 * bandwidth + (k2 * bandwidth)/(256 -
> > > > > > > load) + k3 * delay]
> > > > > > >
> > > > > > > If k5 does not equal zero, an additional operation is
> > > > > > > performed:
> > > > > > >
> > > > > > > metric = metric * [k5/(reliability + k4)]
> > > > > > >
> > > > > > > Bandwidth is inverse minimum bandwidth of the path in
> > > > > > > BPS scaled by a factor of 2.56*1012. The range is from
> > > > > > > a 1200-bps line to 10 terabits per second. ..."
> > > > > > >
> > > > > > > The variance command is a multiplier for what you
> > > > > > > consider a valid path for load balancing. If your
> > > > > > > metric were 3, you would be saying that the router can
> > > > > > > load balance any paths with a metric that is up to 3
> > > > > > > times the metric of the path with the lowest metric.
> > > > > > >
> > > > > > >
> > > > > > > Marvin Greenlee
> > > > > > > Network Learning, Inc.
> > > > > > > marvin@ccbootcamp.com
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > --- Ty <tycampbell@comcast.net> wrote:
> > > > > > > > what is the formula for configuring variance for
> > > > > > > > eigrp ?
> > > > > > > >
> > > > > > > > Thanks!
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > __________________________________
> > > > > > > Do you Yahoo!?
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> > > > > >
> > > > > >
> > >
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