BGP

[benolyndav]

HI

If I have dual connections to the same ISP, and im my route maps I say set community 28 for one connection and set community 29 for the other connection, what is this telling the ISP side and how does it influence any routing desicions please .

Thanks

[marce1000]

 - A BGP community number is a 32-bit value used as a tag attached to BGP routes exchanged between routers.
    It provides a method for adding extra information to BGP routes.
    I would strongly recommend that you synchronized the desired settings with the ISP (and ask for it) ; taking the opportunity to get an explanation too ,

 M.

[MHM Cisco World]

still looking for answer ?

If you want I can run lab and show you some point about using community in control traffic 

MHM

[AshSe]

A BGP community is an optional transitive BGP attribute that can traverse from AS to AS. The BGP communities can be set, removed, or modified selectively (e.g., you can add additional communities). BGP communities can be used to tag routes with the purpose of enforcing routing policies. To give an example, when a route received has a specific BGP community attached to it, the router can perform various operations on other BGP attributes of that route.

There are four well known BGP communities:

• Internet: Prefix can be advertised to all BGP neighbors.
• No-Advertise: Prefix should not be advertised to any BGP neighbors.
• No-Export: Prefix should not be advertised to any External BGP neighbors.
• Local-AS: Prefix should not be advertised outside of the sub-AS.

While a BGP community is not a BGP attribute that is evaluated in order to select the best route, it allows the operator to influence the result of the BGP best path selection algorithm.

Please share your Topology and Configuration to support you better.