From: Patrick Bikar (pbikar@xxxxxxxxx)
Date: Thu Jan 18 2001 - 15:07:40 GMT-3
Don't think so. All will depend of the kn values as :
BWeigrp = k1*BW + k2/delay + function of (k3,k4,k5,load,rel)
by default, k3,k4,k5==0, so you won't use rel and load. You may want to change
the kn values to take load and rel into account.
hth,
cheers, patrick.
At 10:27 18/01/2001 -0600, Alan Basinger wrote:
>I think if I am not mistaken I read that bandwidth and delay are the 2
>primary values used in calculating path selection but in the event of a tie
>in those values the remaining values are considered?
>
>Alan Basinger
>Systems Engineer
>SBC DataComm
>Houston Texas
>abasinge@swbell.net
>
> | |
> ||| |||
> .|||||. .|||||.
>.:|||||||||:.:|||||||||:.
> C i s c o S y s t e m s
> Certified Gold Partner
>
>
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
>Chuck Larrieu
>Sent: Thursday, January 18, 2001 10:14 AM
>To: Schmitt, Greg; 'CCIE newsgroup (E-mail)'
>Subject: RE: Metrics when redistributing.
>
>
>I believe the experiment I detail below indicates that in effect it does
>not matter. (E)IGRP metric is bandwidth and delay, unless you physically go
>in and change them. My experiment indicates that even though the
>redistribution command requires numbers, the default calculation ignores
>those values.
>
>Chuck
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Schmitt, Greg
>Sent: Thursday, January 18, 2001 5:30 AM
>To: 'Chuck Larrieu'; 'Alan Basinger'; 'Virnoche, Phil'; 'CCIE newsgroup
>(E-mail)'
>Subject: RE: Metrics when redistributing.
>
>Greetings,
>
>Just watching this thread, and Alan is correct, you have the load and
>reliability switched here. It's probably a typo, but I
>wouldn't want any newbies to get confused here.
>
>I can't imagine you would ever want to have your load setting maxed out
>(255) and your reliability set to the min. Here is
>the explaination of the igrp metric settings from the ios:
>
>r5(config-router)#router ig 10
>r5(config-router)#redis os 10 met ?
> <1-4294967295> Bandwidth metric in Kbits per second
>
>r5(config-router)#redis os 10 met 10000 ?
> <0-4294967295> IGRP delay metric, in 10 microsecond units
>
>r5(config-router)#redis os 10 met 10000 10 ?
> <0-255> IGRP reliability metric where 255 is 100% reliable
>
>r5(config-router)#redis os 10 met 10000 10 255 ?
> <1-255> IGRP Effective bandwidth metric (Loading) where 255 is 100%
>loaded
>
>r5(config-router)#redis os 10 met 10000 10 255 1 ?
> <1-4294967295> IGRP MTU of the path
>
>r5(config-router)#redis os 10 met 10000 10 255 1 1500 ?
> match Redistribution of OSPF routes
> metric Metric for redistributed routes
> route-map Route map reference
> <cr>
>
>So, the normal setting for an ethernet port would be someting like:
>
>redis os 10 met 10000 10 255 1 1500
>
>Cheers,
>
>Greg Schmitt
>
>Internetwork Solutions Engineer
>ThruPoint, Inc. (formerly Total Network Solutions)
>Voice: 410-349-9772
>Cell: 443-822-5183
>Pager: 888-773-0423 or pager.gschmitt@thrupoint.net
>e-mail: GSchmitt@thrupoint.net
>
>
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
>Chuck Larrieu
>Sent: Wednesday, January 17, 2001 10:17 PM
>To: Alan Basinger; Virnoche, Phil; CCIE newsgroup (E-mail)
>Subject: RE: Metrics when redistributing.
>
>
>Ya got me. Some things I think it better to just be a monkey. The command
>calls for numbers. Use standard easy to remember numbers.
>
>Slattery seems to prefer the load = 255 and the reliability = 1
>
>Just before Thanksgiving I posted the following results of an experiment I
>did ( posted to the regular groupstudy list ) I dug it out and here is what
>I found at that time:
>
>---------------------
>begin the previous post
>
>Bandwidth Delay Load Reliability MTU resulting route metric
>1000 100 255 255 1500 12,100
>1000 50,000 255 255 1500 62,000
>1000 100 255 1 1500 12,100
>1000 100 1 255 1500 12,100
>1000 100 1 255 1 12,100
>2000 100 1 255 1 8,576
>
>it would appear, then, that ( as we have been told by Cisco ) that only
>bandwidth and delay are the driving force in determining the route metric.
>Slattery's book contains a formula for calculating the metric, but I can't
>get the numbers to match up. There seems to be a constant of 11,000 that I
>can't account for. And while it is intuitively clear that higher bandwidth,
>as configured in the last line of the table, should lead to a lower metric,
>I would expect that twice the bandwidth would result in half the metric, not
>2/3's of it.
>
>EIGRP works in a similar manner, so I presume that the calculations are
>roughly the same, and that the load, reliability, and MTU factors are of no
>import, unless one has manually changed the K values using the metric
>weights command.
>
>Hmmmm..... now that's interesting. I thought these values had to match on al
>routers in the AS. Just changed the defaults on one router, and all routes
>are still appearing, even after multiple clear ip route * commands.
>--------------------
>end of previous post
>
>
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Alan
>Basinger
>Sent: Wednesday, January 17, 2001 6:28 PM
>To: Chuck Larrieu; Virnoche, Phil; CCIE newsgroup (E-mail)
>Subject: RE: Metrics when redistributing.
>
>Chuck isn't it 1 load (min) and 255 reliability (max). That usually is the
>case in most scenarios and in most of the information I have read including
>EIGRP network design. I would assume you would need to know the metrics of
>the protocol your distributing from and to? Also it depends on if you want
>to manipulate which routes or paths are preferred in that particular routing
>protocol. For example. In rip you inject a route that is 10 hops away but
>adjust the metrics to make it appear 2 hops away to RIP so RIP will use the
>T3 instead of the 56k link. (This is probably not something one would want
>to do without understanding the consequences of an adjustment like this but
>you get the idea). I know in BGP you use these to manipulate path selection
>and can do the same in IGP's. But then I could be completely wrong :) Hope
>this helps.
>
>
>I have pulled my hair out many a night trying to memorize and understand the
>metrics and how they effects path selection for all the routing protocols
>and decided screw it I'd rather just look them up haha. Now if I could only
>find them all in one place on the doc CD life would be grand. Can any of you
>out there help on that one??
>
>Alan Basinger
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
>Chuck Larrieu
>Sent: Wednesday, January 17, 2001 4:51 PM
>To: Virnoche, Phil; CCIE newsgroup (E-mail)
>Subject: RE: Metrics when redistributing.
>
>
>The Slattery / Burton book Advanced IP Routing in Cisco Networks is a bit
>better in explaining things. While both Slattery and Caslow, in many
>instances, assume far more background than does Doyle, in some cases
>Slattery offers some very good examples and discussion.
>
>A couple of comments below:
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Virnoche, Phil
>Sent: Wednesday, January 17, 2001 11:19 AM
>To: CCIE newsgroup (E-mail)
>Subject: Metrics when redistributing.
>
>
>Question: When redistributing routes into OSPF and EIGRP, how does one
>determine the metrics to use? Is there any good documention that exists that
>eplains this?
>
>CL: in terms of good practice, one should probably not be too fancy, but
>should stick with accurately representing the network topology However,
>experienced engineers do use metrics to manipulate or otherwise influence
>routing policy.
>
>Caslow's book only says that it is necessary to provide metrics but is very
>lacking on how these are determined.
>
>FOR EXAMPLE:
>
>router eigrp 1
> redistribute static metric 10000 100 255 1 1500
>
>CL: this places static routes into the EIGRP routing process, and attributes
>to them an EIGRP metric based on 10 megabits bandwidth, 100 microsecond
>delay, a load of 255 ( max ) a reliability of 1 ( minimum ), and an MTU of
>1500 bytes If you are in to self inflicted pain, you can use these numbers
>to calculate what shows up in the routing table in the metric column.
>
>router ospf 1
> redistribute eigrp 96 metric 20 metric-type 1 subnets
>
>CL: this places EIGRP originated routes into the OSPF process as external
>type 1 routes ( as the route passes through the OSPF domain, OSPF metrics
>are added to the redistribution assigned metric of 20 ) and all subnets are
>passed into the OSPF domain as well. ( as opposed to a summary, or not at
>all if you omit the "subnets" keyword. ) In OSPF the metric is cost, which
>in turn is 10^8 / bandwidth. The metric of 20 means the administrator is
>telling OSPF to consider the EIGRP originated routes as the equivalent of a
>5 megabit line, or a bit more than three T1's.
>
>
>Danka !
>
>Philip G. Virnoche CCNA
>Network Engineer - AT&T Wireless
>phone: 425.580.5239
>cell: 206.601.3134
>
>"HAM AND EGGS - A day's work for a chicken; A lifetime commitment for a
>pig."
>
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