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Quick question on BGP Community approach

Folks, imagine that Corporate border routers will be setup with a BPG community. I will establish BGP session from my side.

Is it usually recommended that I use or process somehow the community value and take advantage of that?
Or if I can make my traffic flow already on my border routers (by using prefix-lists to identify traffic pattern)  without use of the community attribute it is no big deal if I use such community information sent to me?


I just would like to get a thought on best practices on this.

------------------------------------------

Example:

From Corporate_Border_Router4

!

router bgp 200

no synchronization

bgp log-neighbor-changes

network 4.4.4.4 mask 255.255.255.255

neighbor 10.2.47.204 remote-as 100

neighbor 10.2.47.204 password cisco

neighbor 10.2.47.204 send-community

neighbor 10.2.47.204 route-map RM_TO_R2_IN in

neighbor 10.2.47.204 route-map RM_TO_R2_OUT out

no auto-summary

!

ip as-path access-list 1 permit 100

ip as-path access-list 1 permit ^100$

!

ip prefix-list LIST_ENG seq 5 permit 10.1.0.0/16

!

route-map RM_TO_R2_IN permit 10

match ip address prefix-list LIST_ENG

match as-path 2

set community 23127298 23128100

!

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Bronze

Re: Quick question on BGP Community approach

Whatever makes it easier for you. Communities provides a concept of tagging where you can perform traffic engineering based on that tag instead of classifying traffic against an ACL or prefix-list.

With BGP, you have the advantage of using AS_PATH as another form of traffic identification and perform traffic engineering based on this BGP attribute.

Again, there is no best practice as to when to use community or not.

With that said, plenty of ISPs use community for ingress traffic on their backbone and will perform traffic engineering in behalf of their customer if a specified community is sent to them. Consult your ISP for their communities and make use of them if necessary.

1 REPLY
Hall of Fame Super Bronze

Re: Quick question on BGP Community approach

Whatever makes it easier for you. Communities provides a concept of tagging where you can perform traffic engineering based on that tag instead of classifying traffic against an ACL or prefix-list.

With BGP, you have the advantage of using AS_PATH as another form of traffic identification and perform traffic engineering based on this BGP attribute.

Again, there is no best practice as to when to use community or not.

With that said, plenty of ISPs use community for ingress traffic on their backbone and will perform traffic engineering in behalf of their customer if a specified community is sent to them. Consult your ISP for their communities and make use of them if necessary.

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