From: Richard Dumoulin (richard.dumoulin@vanco.es)
Date: Mon May 31 2004 - 00:56:22 GMT-3
Sometimes I am involved in so complicated labs that I tend to forget basic
stuff. This is why I suggest you to do less complicated scenarios from time
to time like Tom Larus e-book at IPExpert. He will soon release volumeII I
believe. You will practice speed and you will refresh forgotten concepts
like split-horizon etc... Also the first 18 labs of IPExpert book are good
for this. You'll have the opportunity to focus on one technology at a time
;)
--Richard
Note: To be honest, yersteday I did one of Tom's labs that was precisely
talking about auto-summary !!
http://www.cisco.com/en/US/tech/tk365/tk80/technologies_q_and_a_item09186a00
800949e8.shtml#five
Go back to basics !!
-----Original Message-----
From: Richard Dumoulin
Sent: lunes, 31 de mayo de 2004 5:38
To: Ahmed Mustafa
Cc: ccielab@groupstudy.com
Subject: RE: summary route
Ahmed, auto-summary is not only used when redistributing igp into bgp.
Suppose you have the subnet 156.1.2.0/24 in your local routing table. If you
enable auto-summary and configure network 156.1.0.0 under BGP, you will
advertise this route as a classful network.
Attaching a prefix-list is only policing traffic. This is not a way to
advertise a network. There 4 ways to advertise:
redistribute
network
aggregate
bgp inject-map
So you solution should come from one of these four ways,
HTH,
--Richard
-----Original Message-----
From: Ahmed Mustafa [mailto:ahmed.mustafa@sbcglobal.net]
Sent: lunes, 31 de mayo de 2004 4:58
To: Richard Dumoulin
Subject: Re: summary route
Richard,
I am confused. Under BGP process, the auto-summary keyword is only used if
I redistribute the route. CCIE labs don't allow to create a static route,
so that option is no permittable.
2nd option to use aggregate address with the summary-only keyword. That is
also restricted by the task I am currently doing
3rd option, I thought I could use prefix-list of 156.1.0.0/16 and attach it
with the neighbor command under the BGP process, but you are saying it won't
work.
Is it because that I have to have a same route 156.1.0.0/16 in my routing
table, and then prefix-list can allow only this route to be advertiseable to
the backbone, and then implicit deny will deny all the subnets of 156.1.0.0
network.
Now the question is how to do that.
May be I could just advertise the network 156.1.0.0 under bgp process, that
will create a 156.1.0.0 route in a BGP table though, not routing table.
I am lost.
Any clue.
Ahmed
----- Original Message -----
From: Richard Dumoulin <mailto:richard.dumoulin@vanco.es>
To: Ahmed Mustafa <mailto:ahmed.mustafa@sbcglobal.net> ;
ccielab@groupstudy.com <mailto:ccielab@groupstudy.com>
Sent: Sunday, May 30, 2004 7:04 PM
Subject: RE: summary route
I don't see how you would end up advertising the route. With the prefix-list
you are just allowing it.
I can see three options:
--Aggregate command
--"auto-summary" + "network 156.1.0.0" under the bgp process.
--you summarise in igp and redistribute it into bgp ,
As the first two options use bgp summary features I would do the last one,
HTH,
--Richard
-----Original Message-----
From: Ahmed Mustafa [mailto:ahmed.mustafa@sbcglobal.net
<mailto:ahmed.mustafa@sbcglobal.net> ]
Sent: lunes, 31 de mayo de 2004 3:44
To: ccielab@groupstudy.com
Subject: summary route
If I want to announce a summary route of my internal network towards the
Backbone router, and not allowed to use the route-summary in BGP.
Will the following solution work:
ip prefix-list TOBB permit 156.1.0.0/16 -------------------> Assuming my
internal network is comprise of 156.1.0.0/16 network, and scattered
throughout the netowork with /24 bit mask.
router bgp 100
neighbor 1.1.1.1 remote-as 230
neighbor 1.1.1.1 prefix-list TOBB out
I didn't use the command aggregate-address. I am assuming by saying not use
route-summary means I can't use aggregation.
The implicit deny at the end should block all the longer routes.
Please advise
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