From: Alan Basinger (abasinge@xxxxxxxxxx)
Date: Wed Jan 17 2001 - 23:27:57 GMT-3
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."
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:27:33 GMT-3