Re: [babel] Babel filtering: routing policies

[Mahesh Jethanandani <[e-mail]>]

> On Aug 23, 2019, at 3:27 PM, Juliusz Chroboczek <[e-mail]> wrote:
> 
>> In order to make sure we are talking the same language, would you say a given
>> chain is equivalent of a “defined set” as defined by
>> draft-ietf-rtgwg-policy-model?
> 
> No.  A chain would correspond to a sequence of policy statements, if
> I read this document right.

According to the routing policy draft.

   Policy statements in turn consist of simple condition-action tuples.

but what you seem to be defining by “install”, “redistribute” and “out” are ...

   The models provides a set of generic sets that can be used for
   matching in policy conditions.  These sets are applicable for route
   selection across multiple routing protocols.  They may be further
   augmented by protocol-specific models which have their own defined
   sets. 

If not, how would you define your sets?
 
> 
>> I understand that these are babel specific,
> 
> I think that only matching on router-id is Babel-specific, all the others
> are fairly generic.
> 
>> will extend the policy model to add these chains as “defined sets".
> 
> I don't think you need to extend anything.  Matching on router-id is not
> essential.
> 
> On the other hand, it looks to me like it's more expressive than anything
> that any implementation of Babel known to me has ever implemented.  Since
> I'm still not sure what's the purpose of the YANG model, I don't know if
> that's a problem or not.

If any particular implementation does not support the more expressive policy statement, they can choose to deviate (not support) these policies. It can choose to support only the policies it defines.

Thanks.

> 
>>    There exist other actions, more specialised -- see the manual page for
>>    details.
> 
>> I see two more, src-prefix and table. Is there more?
> 
> Not in babeld.  I haven't checked BIRD.
> 
> -- Juliusz