Re: [Idr] WG Adoption call draft-ymbk-idr-bgp-open-policy - (6/6 to 6/20/2016)

[Job Snijders <[e-mail]>]

Hi Randy,

On Thu, Jun 09, 2016 at 12:37:10PM -0700, Randy Bush wrote:
> > Secondly (and more importantly), the roles are not necessarily a BGP
> > session-specific characteristic, but rather a prefix-specific
> > property.  The proposed OPEN method does not provide for this level
> > granularity if I am reading it correctly. The method would affect all
> > prefixes exchange over a BGP session, without exception.
> 
> i can not be sure, as you lack example. but the example i commonly use
> is when A gives B local peering and also sells B global transit.
> today, this is two separate sessions. do you use another approach; not
> can think of, but actualy use?

Yes, using two separate sesssions to deliver the two separate products
is a common (and valid) approach. 

> are there other real-world examples?  just trying to understand.

I won't share the company names involved, but on multiple occasions, my
employer has engaged in providing transit between two peering partners.
This was either done unilaterally (when my employer has a desire to keep
the internet together), or part of a bilateral commerical agreement. In
other words I cannot assume the BGP peer will cooperate with its role
assignment.

In all those cases, under the "OPEN" approach, we'd flag all involved
parties as 'peer', and the peer would have assigned us the role 'peer'
too, except that they weren't in some specific contexts.

There are at least two use-cases:

    - some prefixes are 'peering', others are 'transit': this has
      happened for instance when redistributing root-server prefixes
      that were behind a peer to other peers.
    - all prefixes are peering, except they should be redistributed to
      peer X too (can be decided unilaterally or bilaterally).

Reflecting on the two examples, the common theme is that if you are a
stub network (e.g. one does NOT provide IP Transit using BGP to your
customers) the "OPEN"-approach may be a reasonable approach, but for a
transit network the approach feels too restrictive.

Kind regards,

Job