BGP Community - AS0 is de-facto "no-export-to" marker - Any ASN reserved to "export-only-to"?'

Mark Tinka mark.tinka at
Wed Sep 9 15:19:30 UTC 2020

On 9/Sep/20 15:25, Robert Raszuk wrote:

> That's not quite true. 
> See the entire idea behind defining a common mechanism for signalling
> policy in communities in a flexible way for both intra and
> inter-domain use is to help you to use the same encoding acros policy
> engines of many vendors. 
> I would actually risk to say that it could be even more applicable
> intra-domain then inter-domain. 
> See the crux of the thing is that this is not just about putting bunch
> of type-codes into IANA reg. It is much more about uniform encoding
> for your actions with optional parameters across vendors. 
> In fact the uphill on the implementation side is not
> because signalling new value in BGP is difficult to encode ... it is
> much more about taking those values and translating those to the run
> time policies in a flexible way. 

But how does that scale for vendors? Let me speak up for them on this
one :-).

We are now giving them extra work to write code to standardize
communities for internal purposes. What extra benefit does that provide
in lieu of the current method where Juniper send 1234:9876 to Cisco, and
Cisco sees 1234:9876?

Should a vendor be concerned about what purpose an internal community
serves, as long as it does what the Autonomous System wants it to do?

Unless I am totally misunderstanding your goal.

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