Re: [Idr] WG adoption call for draft-ymbk-idr-bgp-open-policy (5/20 to 6/3/2017).

[David Monosov <[e-mail]>]

On 6/4/17 1:59 PM, Job Snijders wrote:
> 
> On Fri, 2 Jun 2017 at 20:06, Ruediger Volk, Deutsche Telekom Technik - FMED-41..
> <[e-mail] <mailto:[e-mail]>> wrote:
> 
>       > This begins a 2 week WG Adoption call for draft-ymbk-idr-bgp-open-policy
>       > (5/20 to 6/3/2017)
>     I strongly support adoption,
>     and consider it a worthy candidate for the being progressed quickly.
> 
> 
> 
> Unfortunately, as it's currently specified, I still cannot see my affiliation
> deploying this technology in a meaningful way. 

Concur. Despite a laudable goal, in its current form this technology would
significantly constrain the flexibility afforded by community based policies,
which are widely deployed.

Attempting to "codify" the nature of relationships between autonomous systems
into 4 broad categories is an oversimplification that has limited overlap with
operational reality (as demonstrated by increasingly broad and expressive
selection of policy communities implemented by sophisticated networks).

Having to firmly constrain the nature of each relationship in advance, on a
session level rather than prefix level, requires the operators to make a choice
between two less than ideal alternatives:

- Correctly select a conservative definition of their current relationship,
reducing the operational agility if the nature changes in the future - as now
both operators must agree in advance and implement a change in the definition of
this relationship, flapping the session, prior to modifying policy.

- Err on the side of caution and tag all sessions as "complex" to maintain that
agility, eliminating the benefit of this technology.

Regardless of the alternative initially chosen, it seems plausible that an
autonomous system with an evolving set of roles and interconnects will find
itself over time drifting toward ever more of them marked "complex" as its
policy sophistication requirements evolve.

Perhaps a better direction for this initiative, in lieu of BGP extension, would
be toward a BCP outlining a checklist for defining the nature of each
relationship as part of the on-boarding process for new interconnects - and
providing some policy implementation examples for various cases.

--
Sincerely yours,

David Monosov