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02-08-2013 05:06 AM - edited 03-04-2019 06:58 PM
Hi,
Just a quick one...
Do deny statement in prefix-list / access-list works for advertise-map in BGP conditional advertisement ??
I tried a lot of combinations, but it is not working; so just need to confirm is there anything I'm missing.
PS: Talking about the deny statement in prefix-list / Access-list in route-map for Advertise-map and NOT non-exist-map or exist-map.
Regards,
Smitesh
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02-10-2013 11:15 PM
Hello Smitesh,
your test results show that a prefix matching a deny statement in a prefix-list invoked in the advertise-map is NOT processed by the BGP conditional advertisement feature, and so it is always advertised regardless of exist-map or non-exist-map.
This makes sense as the advertise-map should list the IP prefixes to be advertised conditionally depending on the state of the exist-map or non-exist-map.
All IP prefixes not matching the advertise-map are not considered for conditionally advertising including those matching a deny statement in the IP prefix-list invoked within the advertise-map.
Hope to help
Giuseppe
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02-08-2013 05:41 AM
Hi,
you need to permit the prefixes you want to conditionnaly advertise.
Regards
Alain
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02-08-2013 06:17 AM
Hello,
Are you specifying an condition for the advertised route?
Pleaser post you confg for this conditional route advertisement?
res
paul
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Paul
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02-08-2013 07:27 AM
Hi Cadet,
Thanks for your feedback; so shall I take that as deny statements in prefix-list /access-list are ignored irrespective of whether it is advertise-map or exist-map or non-exist-map.
Regards,
Smitesh
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02-08-2013 04:17 PM
Hello
I am not clear on what you are trying to achieve with your deny statements?
If you want to deny or permit a specific route in aggregation, then suppress-map can be used.
The suppress-map logic can use deny/permit acls, with the logic of :
Permit=suprress the route
Deny =not to suppress the route
Advertise-map are to determine what AS path information is retained when performing aggregation on the basis that only if a more specific route of the aggregate is in the bgp table and the as-set option applied.
This can be accomplished by acl or ip as-path acl using permit statements.
res
Paul.
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Paul
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02-08-2013 09:10 PM
Hi Paul,
Aggregation and suppress-map are not classified as conditional advertisement as far as Cisco DOC goes.
Secondly, Its was not something of production issue, but I was just playing around with BGP in dynnamips ( haven't saved configs ). So where I discovered that
neighbour X.X.X.X advrtise-map ABC exist-map/non-exist-map XYZ
It is documented in cisco DOCs even that deny statement in the prefix-list / access-list in route-map associated with exist-map or non-exist-map ( as per above XYZ )are ignored; however nothing has been said about advertise-map.
When I was playing with the same, I found that any deny statement in prefix-list/ access-list associated with route-map for advertise-map ( as per above ABC ) doesn't have any effect; whatsoever logic you try to implement.
Regards,
Smitesh
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02-09-2013 12:55 AM
Hello Smitesh -
I mis-understood your use of the advertise-map, I thought it had to do with you performing aggregation, going by your first query -PS: Talking about the deny statement in prefix-list / Access-list in route-map for Advertise-map and NOT non-exist-map or exist-map
So i took this as you didn't want the conditional part of the exist-map or not exist maps to be included, so that's why I wrongly steered you towards to aggregation and using the suppress-map option.
res
Paul
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Paul
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02-09-2013 02:28 AM
Hi,
the prefixes to advertise have to be permitted in the prefix-list matched in the advertised-map
Regards
Alain
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02-09-2013 05:31 AM
Hi Alain,
Thanks again, so deny statements in prefix-list matched in the advertise-map are ignored ??
Thats what my question is.
Regards,
Smitesh
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02-09-2013 05:53 AM
Hi,
they are not advertised, doe that answer your question ?
Regards
Alain
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02-09-2013 09:49 PM
Alain,
Unfortunately, whether the condition ( exist-map or non-exist-map ) is true or false; what I have observered is that prefixes which are denied are always advertised.
Regards,
Smitesh
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02-10-2013 11:15 PM
Hello Smitesh,
your test results show that a prefix matching a deny statement in a prefix-list invoked in the advertise-map is NOT processed by the BGP conditional advertisement feature, and so it is always advertised regardless of exist-map or non-exist-map.
This makes sense as the advertise-map should list the IP prefixes to be advertised conditionally depending on the state of the exist-map or non-exist-map.
All IP prefixes not matching the advertise-map are not considered for conditionally advertising including those matching a deny statement in the IP prefix-list invoked within the advertise-map.
Hope to help
Giuseppe
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02-09-2013 02:43 AM
Hi Smithesh,
If u r using deny statement in prefixlist go for exist map nd if u r using permit prefixlist the go for non exist map
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02-09-2013 05:34 AM
Hi Bibin,
You talking about deny statement in prefix-list matched for exist-map / non-exist-map ??
If thats the case, then deny statement matched in exist-map / non-exist-map are ignored.
And if you talking about deny statements in prefix-list matched in advertise-map, do you have any working solution you can present ? Asking as I have tried every possible logics for route-map.
Regards,
Smitesh
