Re: eigrp variance and traffic-share

From: wing_lam@jossynergy.com
Date: Thu Jan 20 2005 - 22:23:52 GMT-3

Hi, group;

If I want to share traffic evenly without regarding the metric, even the
metric not the same, can it be done?

i.e. I have three routes to 192.168.7.0/24, with EIGRP Metric 128000,
256000 &384000, the variance is large enough that all the route is entered
the route table. But I don't want the path with least metric sends majority
of traffic. Can I distribute evenly in these three paths? (i.e. round
robin)

Thanks,
BBD

                                                                                                                                       
                      "Mark Lasarko"
                      <mlasarko@co.ba.m To: <ccielab@groupstudy.com>, <hashng@yahoo.com>
                      d.us> cc:
                      Sent by: Subject: Re: eigrp variance and traffic-share
                      nobody@groupstudy
                      .com
                                                                                                                                       
                                                                                                                                       
                      01/21/2005 04:20
                      AM
                      Please respond to
                      "Mark Lasarko"
                                                                                                                                       
                                                                                                                                       

Greetings Hashiru,

Variance will help control what routes to include by use of a
multiplier.
Including routes with "A metric less than "n" times the minimum metric
route for that destination."
The variable "n", of course, is what follows the 'variance' command.

Whereas 'traffic-share' will control how traffic is distributed among
known routes when multiple routes to a destination exist, meaning they
are already present in the routing table.

I like to remember 'variance' as kind of internal/before... influencing
what routes we might use.

Whereas 'traffic-share' is more external/after... once we know about
routes, having determined we may use them, how we distribute traffic
among those paths if more than one exists.

That said, they can certainly be used together.

For example:

router eigrp 100
 variance 3
 traffic-share (balanced | min)
 ...

Take a few minutes to check out the options on the traffic-share
command.

Rack1R1(config-router)#variance ?
  <1-128> Metric variance multiplier

Rack1R1(config-router)#traffic-share ?
  balanced Share inversely proportional to metric
  min All traffic shared among min metric paths

Here's a link with a diagram that explains the variance calculation:
http://www.cisco.com/warp/public/103/19.html

HTH,
~M

ontrol how traffic is distributed among routes when there are multiple
routes for the same destination network that have different costs,

he variance command to instruct the router to include routes with a
metric less than n times the minimum metric route for that destination,
where n is the number specified by the variance command

>>> "Idris, Hashiru Aminu" <hashng@yahoo.com> 1/20/2005 2:19:36 PM >>>

i just couldn't get the real difference between the two commands with
regards to EIGRP below
Variance X
traffic-share .......
can one be used instead of the other? do they work Collaboratively?
because they all seem to be for load ballacing.
please can someone shade some light on this in an illustrative manner
TIA
Hashiru Idris

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