From: Herbert Maosa (asawilunda@googlemail.com)
Date: Wed Oct 24 2007 - 19:56:45 ART
Jo,
that would qualify for my bullet point number 1. The protocol is already
carrying external routes.
Herbert.
On 10/24/07, Joseph Brunner <joe@affirmedsystems.com> wrote:
>
> Yes, but Herbert, what if all ospf routes are external that we are
> getting feedback from
>
>
>
> (i.e. the task wanted redistributed connected to ospf)
>
>
>
> Then we can't filter that way
>
>
> ------------------------------
>
> *From:* Herbert Maosa [mailto:asawilunda@googlemail.com]
> *Sent:* Wednesday, October 24, 2007 6:37 PM
> *To:* Joseph Brunner
> *Cc:* Jeffrey Biggs; ccielab@groupstudy.com
> *Subject:* Re: Redistribution with route tags are KILLING ME!!!`
>
>
>
> Actually, I use route-tags in two cases
>
> - one of the protocols is already carrying external routes from
> elsewhere
> - one of the protocols is RIP, which has no concept of External
> routes
>
> Except for these two cases, so far I successfullly implement loop free
> redistribution by matching internal routes ( in the case of OSPF ) or
> matching route-type Internal ( for the case of EIGRP ).
>
> I think the use of route-tags is generally overused, perhaps overtrained,
> so much so that you end up using it on every redistribution scenario
without
> understanding what you are trying to accomplish. Could waste quite a lot of
> time at the best, and you could get it all wrong at the worst !
>
> .
> Herbert.
>
> On 10/24/07, *Joseph Brunner* <joe@affirmedsystems.com> wrote:
>
> Wait slow down...
>
> You only NEED to use redistribution with route-tags when you have more
> than
> 1 router doing mutual route re-distribution. We use the tags to block
> route
> feedback. That is, if a route has been redistributed already at either
> router it wont be re-redistributed back to the source protocol at the
> other
> router.
>
> Here is an example... R3 and R4 are redistributing between EIGRP & OSPF.
> To
> prevent a loop we don't allow route feedback from a protocol back into a
> protocol. Anything going from OSPF to EIGRP, and EIGRP to OSPF is tagged
> and
> the redistribution at other router denies routes with that tag before
> redistribution. The tags allow us to know WHERE that route originally came
>
> from.
>
> Here is the topology
>
> R1---OSPF--- R3--- EIGRP-AS-10--- R5
> | |
> R2---OSPF--- R4--- EIGRP-AS-10--- R6
>
>
> R3&R4
>
> Router ospf 1
> Redis eigrp 10 subnets route-map watch-tag
>
> Router eigrp 10
> Redistribute ospf 1 route-map watch-tag metric 1500 100 255 1 1500
>
> Route-map watch-tag deny 5
> Match tag 5
> Route-map watch-tag permit 10
> Set tag 5
>
>
> Try it with my topology in your dynamips...
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Jeffrey Biggs
> Sent: Wednesday, October 24, 2007 4:48 PM
> To: ccielab@groupstudy.com
> Subject: Redistribution with route tags are KILLING ME!!!`
>
> I have been trying to grasp the use of redistribution using only route
> tags,
> but I just keep getting killed by it. I can redistribute using
> prefix-lists
> and ACL's all day long, but I know I am going to see something where I
> need
> to "make sure all IP's are fully reachable without the use of
> ACL's/Prefix-lists" and I am going go down in flames..Is there someone out
> there that has a solution that can help me??????? I have used NMC and
> IPEXPERT (BOTH VERY GOOD TOOLS, NOT KNOCKING ANY OTHERS) but my brain is
> just not grasping the concept.
>
>
>
> HELP!!!!!!!
>
>
>
> Thanks
> JB
>
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