From: Chuck Larrieu (chuck@xxxxxxxxxxxxx)
Date: Mon Jan 29 2001 - 04:33:50 GMT-3
This has been fun. Several practice labs have left me realizing I didn't
understand the distribute-list function all that well. Thanks to some of you
here for your posts on the subject. And let me follow up with a report on my
own experiments.
Igrp_domain-----redistribution_router---------rip_domain
Pretty simple lab. Played around with access-lists and redistribution and
distribute-list out. It is indeed as someone here pointed out. A better
command might have been "redistribute-list" It would appear that the
distribute-list works in conjunction with the redistribute command under the
routing protocol configuration. So now I believe I understand. The routing
protocol is redistributing routes from a different routing protocol, and the
distribute-list out command further determines which of those other routing
protocol 's routes get redistributed. Makes sense now.
OK. I'm a bright boy. So what is the purpose of the distribute-list out
options?
A not quite so quick and dirty lab helps clarify things.
Standard hub and spoke setup, with router_1 being the hub, and routers 2,3,
and 4 being the spokes. Router_2 is IGRP, router_3 is EIGRP ( different AS
number so we have to redistribute ), and router_4 is RIP. Router_1 has all
three protocols enabled, and redistributes among them.
Using loopbacks to simulate 6 subnets on each router, and configuring the
redistribution router appropriately, I can see all routes from all domains
in the routing tables of each domain. Life is good
Next, I want to verify that what I believe about the distribute-list out
options is true. I.e. in the situation I have created on the redistribution
router, distribute-list out options are the means of accomplishing complex
redistribution when several routing protocols are involved on the same
router.
So, in my case, I create several access-lists, each one permitting half of
the subnets for each routing protocol. And I tailor my distribute-list out
commands under each routing protocol configuration to accomplish my goal of
permitting only selected halves of a protocol's subnets to be redistributed
into other protocols.
I know this isn't making much sense, and unfortunately I am too tired to set
things up so that folks can visit my lab and see exactly what I am talking
about. I have included the relevant parts of the redistribution router's
configuration to help clarify things.
Let me just say that I did correctly predict which routes would show up
where prior to applying the distribute lists. So I am taking that as a sign
that this small thing is now making sense to me.
!
router eigrp 500
redistribute rip metric 5000 1000 255 1 1500
redistribute igrp 100 metric 10000 100 255 1 1500
network 192.168.30.0
distribute-list 44 out rip
distribute-list 22 out igrp 100
!
router rip
redistribute igrp 100 metric 10
redistribute eigrp 500 metric 5
network 192.168.40.0
distribute-list 2 out igrp 100
distribute-list 3 out eigrp 500
!
router igrp 100
redistribute rip metric 5000 1000 255 1 1500
redistribute eigrp 500 metric 10000 100 255 1 1500
network 192.168.20.0
distribute-list 4 out rip
distribute-list 33 out eigrp 500
!
access-list 2 permit 192.168.21.0 0.0.0.255
access-list 2 permit 192.168.22.0 0.0.0.255
access-list 2 permit 192.168.23.0 0.0.0.255
access-list 3 permit 192.168.31.0 0.0.0.255
access-list 3 permit 192.168.32.0 0.0.0.255
access-list 3 permit 192.168.33.0 0.0.0.255
access-list 4 permit 192.168.41.0 0.0.0.255
access-list 4 permit 192.168.42.0 0.0.0.255
access-list 4 permit 192.168.43.0 0.0.0.255
access-list 22 permit 192.168.24.0 0.0.0.255
access-list 22 permit 192.168.25.0 0.0.0.255
access-list 22 permit 192.168.26.0 0.0.0.255
access-list 33 permit 192.168.34.0 0.0.0.255
access-list 33 permit 192.168.35.0 0.0.0.255
access-list 33 permit 192.168.36.0 0.0.0.255
access-list 44 permit 192.168.44.0 0.0.0.255
access-list 44 permit 192.168.45.0 0.0.0.255
access-list 44 permit 192.168.46.0 0.0.0.255
!
Got a long day with bootcamp planned for tomorrow. See you all another time.
Chuck
A long shot at passing is better than no shot.
Right now that's all I got to get me through,
So I gotta believe!
( paraphrased from Kathy Baille / Baille and the Boys
a song from several years ago )
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