From: Brian McGahan (brian@cyscoexpert.com)
Date: Thu Jan 09 2003 - 22:39:32 GMT-3
Desmond,
Modify distance only when you are trying to manipulate the
choice of one protocol over another. If you have multiple routes within
that protocol, use metric to modify the path.
Remember that for EIGRP, the bandwidth used in the metric
calculation is the lowest bandwidth along the path, on a per route
basis. This means that it is a big headache to try to influence path
using bandwidth. If you want to manipulate the metric calculation in
EIGRP, use delay. Delay is cumulative throughout the domain.
For EIGRP, the metric calculation is as follows:
metric = [k1 * bandwidth + (k2 * bandwidth)/(256 - load) + k3 * delay]
If k5 does not equal zero, an additional operation is done:
metric = metric * [k5 / (reliability + k4)]
For more info on EIGRP metric calculation:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/
ip_r/iprprt2/1rdeigrp.htm#1018140
HTH
Brian McGahan, CCIE #8593
Director of Design and Implementation
brian@cyscoexpert.com
CyscoExpert Corporation
Internetwork Consulting & Training
Voice: 847.674.3392
Fax: 847.674.2625
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Desmond
> Sent: Thursday, January 09, 2003 4:08 PM
> To: Brian McGahan; 'Aidan Marks'
> Cc: 'Joe Chang'; ccielab@groupstudy.com
> Subject: Re: changing AD for EIGRP External Route (D EX)
>
> Thanks Brian
>
> I got this one from Hellocomputer scenario.
> R1, R2 and R3 on EIGRP domain. R3 have to go through R1 to reach R4
> which
> is on OSPF. I treated EIGRP as OSPF to change the AD from source R1. I
> found
> out it didn't work with "D EX".
> I guess we have to use metric on R3 to make R1 be more preferable.
e.g.
> bandwidth, cost and ..
>
> ---
> |
> R4 OSPF
> --------------------------
> | | EIGRP
> R1 R2
> \ /
> R3
>
>
> ----- Original Message -----
> From: "Brian McGahan" <brian@cyscoexpert.com>
> To: "'Aidan Marks'" <amarks@cisco.com>; "'Desmond'"
> <cciestudy@sympatico.ca>
> Cc: "'Joe Chang'" <changjoe@earthlink.net>; <ccielab@groupstudy.com>
> Sent: Thursday, January 09, 2003 4:58 PM
> Subject: RE: changing AD for EIGRP External Route (D EX)
>
>
> > Instead of changing the distance of the external EIGRP route,
> > just change the distance of the competing route. For example, if
you
> > have a prefix in OSPF with a distance of 110, and a matching
external
> > EIGRP prefix, just change the OSPF distance to 171.
> >
> > When changing distances to influence routing, I usually
> > recommend lowering the distance of the protocol that is higher. The
> > reason for this is so that when you look at the routing table, you
can
> > see that this prefix has a lower distance for a reason. For
example, if
> > you have a RIP prefix competing with an OSPF prefix, and you want to
> > route through RIP, change the distance of this prefix to 109. When
you
> > look in the routing table, you will remember that you lowered the
RIP
> > prefix to win over the OSPF route. Since OSPF is 110, the 109 would
be
> > the indicator that OSPF is the competing protocol. With external
EIGRP,
> > you do not have this option. Therefore you should raise the prefix
in
> > protocol with the lower distance to 171 or above.
> >
> > HTH
> >
> > Brian McGahan, CCIE #8593
> > Director of Design and Implementation
> > brian@cyscoexpert.com
> >
> > CyscoExpert Corporation
> > Internetwork Consulting & Training
> > Voice: 847.674.3392
> > Fax: 847.674.2625
> >
> >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
Behalf
> > Of
> > > Aidan Marks
> > > Sent: Thursday, January 09, 2003 2:33 PM
> > > To: Desmond
> > > Cc: Joe Chang; ccielab@groupstudy.com
> > > Subject: Re: changing AD for EIGRP External Route (D EX)
> > >
> > > This is correct, there is no way right now to change the AD of
> > selected
> > > eigrp external routes, it's all or nothing with the distance eigrp
x x
> > > command.
> > >
> > > Therefore doing something like "distance 170 10.20.30.40 0.0.0.0
100"
> > > won't
> > > work for externals as it applies only to internal routes.
> > >
> > > Aidan
> > >
> > > At 06:14 AM 10/01/2003, Desmond wrote:
> > >
> > > >The distance command only work for routes "D", not "D EX".
> > > >
> > > >----- Original Message -----
> > > >From: "Joe Chang" <changjoe@earthlink.net>
> > > >To: <ccielab@groupstudy.com>
> > > >Sent: Thursday, January 09, 2003 11:59 AM
> > > >Subject: Re: changing AD for EIGRP External Route (D EX)
> > > >
> > > >
> > > > > Hmm, route tagging wouldn't work, the "distance" command
doesn't
> > allow
> > > for
> > > > > matching tags, and policy routing doesn't allow for setting
AD.
> > > > >
> > > > > Your'e best bet is to set the distance command for the
specific
> > > routes.
> > > > >
> > > > > ----- Original Message -----
> > > > > From: "Desmond" <cciestudy@sympatico.ca>
> > > > > To: <ccielab@groupstudy.com>
> > > > > Sent: Thursday, January 09, 2003 12:45 PM
> > > > > Subject: Re: changing AD for EIGRP External Route (D EX)
> > > > >
> > > > >
> > > > > > Sorry, I missed something.
> > > > > >
> > > > > > I meant from particular source.
> > > > > >
> > > > > > ----- Original Message -----
> > > > > > From: "Desmond" <cciestudy@sympatico.ca>
> > > > > > To: <ccielab@groupstudy.com>
> > > > > > Sent: Thursday, January 09, 2003 11:37 AM
> > > > > > Subject: changing AD for EIGRP External Route (D EX)
> > > > > >
> > > > > >
> > > > > > > Is there any way to change the admin distance for EIGRP D
EX
> > > routes ?
> > > > > > >
> > > > > > >
> > > > > > > Thanks
> > > > > > >
> > > > > > > Desmond
> > > > > > > .
> > > > > > .
> > > > > .
> > > >.
> > > .
> .
.
This archive was generated by hypermail 2.1.4 : Sat Feb 01 2003 - 07:33:46 GMT-3