Re: Shared Locator Address Pool (SLAP) protocol proposal

["Spencer Dawkins" <spencer@mcsr-labs.org>]

Dave,

If this proposal can be made to work, that would be lovely. The part
that scares me is having a number of different entities maintaining
this pool (if we had TCP, SCTP, RTP/RTCP, and DCCP on one node, that's
not a small amount of software) - just figuring out why something was
added or deleted seems daunting.

But I'll let others chime in here, one way or the other.

Spencer

----- Original Message ----- 
From: "Dave Crocker" <dhc@dcrocker.net>
To: <multi6@ops.ietf.org>
Sent: Saturday, November 15, 2003 10:45 AM
Subject: Shared Locator Address Pool (SLAP) protocol proposal


> Folks,
>
> A fundamental advantage that transport-based locator-pool schemes
> (SCTP, DCCP, TCP-MH) have over wedge-layer approaches (HIP, LIN6,
> MAST, MIP) is that they can multiplex the control exchange in with
> data traffic, potentially saving on number of packets. Wedge-layer
> approaches are forced to have an explicit, separate exchange. MAST
> makes this asynchronous from the data exchange that uses the locator
> pool; this avoid startup delay. However the basic cost of the
exchange
> remains. If a host must do this exchange with every other host it
> talks to, the aggregate overhead is high.
>
> Deferring use of the mechanism, as Pekka S. described, is one way to
> reduce such traffic.
>
> Wouldn't it be nice if it were possible to have the "enhanced"
> transport services share their lower-cost largesse with the
> wedge-layer schemes?
>
> So, here's the thought:
>
> 1. An endpoint runs Locator Pools (LP) as a resource shared among
different
> consumer services at the endpoint -- eg, a wedge layer service and
an enhanced
> transport service -- potentially with multiple maintainers. (Yes,
the latter
> raises a concern about synchronization, but let's ignore that minor
detail,
> for now.) LPs might vary in their granularity.  Bigger grains makes
it
> more likely that the pool will be shared.  A pool that is the finest
> grain (Connection) can't be shared, of course.
>
> 2. A common Shared Locator Address Pool (SLAP) protocol is used by
the
> different maintenance services, over different communication
channels
> (eg, multiplexed on the transport channel, versus over an
independent
> control channel). The maintenance services also might use different
> "configurations", such as peer-to-peer exchange, versus third-party
> agent mediation.
>
> 3. Enhanced transport services access the pool directly. Legacy
> transport services access the pool via the much-vaunted IP wedge
layer
> service. If an enhanced transport is one of the participants, then
> there really is no need for a wedge-layer service to conduct an
> exchange. This saves packets.
>
> The obvious direction this idea leads is towards an effort to
produce
> a common protocol.  Clearly it should include the locator
> "characterization" attribute-signalling capability that Erik
suggested.
>
> Anyone from the various camps interested in discussing such an
effort?
>
> d/
> --
>  Dave Crocker <dcrocker-at-brandenburg-dot-com>
>  Brandenburg InternetWorking <www.brandenburg.com>
>  Sunnyvale, CA  USA <tel:+1.408.246.8253>
>
>