Posted on December 15, 2020 7:44 am
 |  Asked by Brooks Swinnerton
 |  561 views
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Hi there,

I was wondering how to best scrub large BGP communities that match a certain regex. I’ve tried the following:

ip large-community-list regexp INFORMATIONAL permit 65000:101:.+
!
route-map SCRUB-COMMUNITIES permit 10
set large-community large-community-list INFORMATIONAL delete

But it appears that when running `config-sanity`, it hints the route-map is incorrect:

router(config)#show route-map config-sanity
route-map SCRUB-COMMUNITIES permit 10

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Answered on December 15, 2020 7:54 am

Hi Brooks,

Thanks for reaching out.

The above configuration works only in ArBGP(Multi-agent) Mode.So we need to have this command "service routing-protocols model multi-agent"enabled on the device.

Could you please provide the below outputs from the concerned device so that I can replicate in the lab:

1)What is the EOS version running on the device?

2)"show run sec router bgp"

3)"show run sec route-map"

4)"show run sec community-list"

 

Thanks,

Bhavana.

 

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Posted by Brooks Swinnerton
Answered on December 15, 2020 5:31 pm

Hi Bhavana,

Here's a config that should reproduce the config-sanity problem:

service routing-protocols model multi-agent
!
service routing configuration route-map set-operations sequential
!
ip large-community-list regexp INFORMATIONAL permit 21700:101:[0-9]+
!
route-map PEER-IN permit 10
   set large-community large-community-list INFORMATIONAL delete
!
router bgp 65000
   router-id 1.1.1.1
   neighbor 2.2.2.2 route-map PEER-IN in
   neighbor 2.2.2.2 send-community
   neighbor 2.2.2.2 remote-as 65001
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Posted by Brooks Swinnerton
Answered on December 17, 2020 2:14 pm

I forgot to mention, this can be seen on 4.25.1F.

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Posted by Brooks Swinnerton
Answered on December 17, 2020 2:14 pm

I forgot to mention, this can be seen on 4.25.1F.

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Posted by Brooks Swinnerton
Answered on December 29, 2020 10:07 pm

After testing this in a lab environment, it appears as though config-sanity is incorrect.

ip large-community-list regexp INFORMATIONAL permit 65000:101:.+
!
route-map SCRUB-COMMUNITIES permit 10
set large-community large-community-list INFORMATIONAL delete

Will result in properly removing the large communities that begin with 65000:101:*

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