Destination Preference Attribute for BGP

Fri Aug 18 07:38:07 UTC 2023

Jakob,

With AS-PATH prepend you have no control on the choice of which ASN should
do what action on your advertisements.

However, the practice of publishing communities by (some) ASNs along with
their remote actions could be treated as an alternative to the DPA
attribute. It could result in remote PREPEND action too.

If only those communities would not be deleted by some transit networks
....

Thx,
R.

On Thu, Aug 17, 2023 at 9:46 PM Jakob Heitz (jheitz) via NANOG <
nanog at nanog.org> wrote:

> "prepend as-path" has taken its place.
>
>
>
> Kind Regards,
>
> Jakob
>
>
>
>
>
> Date: Wed, 16 Aug 2023 21:42:22 +0200
> From: Mark Tinka <mark at tinka.africa>
>
> On 8/16/23 16:16, michael brooks - ESC wrote:
>
> > Perhaps (probably) naively, it seems to me that DPA would have been a
> > useful BGP attribute. Can anyone shed light on why this RFC never
> > moved beyond draft status? I cannot find much information on this
> > other than IETF's data tracker
> > (https://datatracker.ietf.org/doc/draft-ietf-idr-bgp-dpa/) and RFC6938
> > (which implies DPA was in use,?but then was deprecated).
>
> I've never heard of this draft until now, but reading it, I can see why
> it would likely not be adopted today (not sure what the consensus would
> have been back in the '90's).
>
> DPA looks like MED on drugs.
>
> Not sure operators want remote downstream ISP's arbitrarily choosing
> which of their peering interconnects (and backbone links) carry traffic
> from source to them. BGP is a poor communicator of bandwidth and
> shilling cost, in general. Those kinds of decisions tend to be locally
> made, and permitting outside influence could be a rather hard sell.
>
> It reminds me of how router vendors implemented GMPLS in the hopes that
> optical operators would allow their customers to build and control
> circuits in the optical domain in some fantastic fashion.
>
> Or how router vendors built Sync-E and PTP into their routers hoping
> that they could sell timing as a service to mobile network operators as
> part of a RAN backhaul service.
>
> Some things just tend to be sacred.
>
> Mark.
>
>
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