[alto] draft-yang-alto-path-vector-03 and cost-map service

[Hans Seidel <[e-mail]>]

Hi Richard, all,

after the ALTO session in Berlin, we shortly talked with Ingmar about 
the impact of path-vector on the size of cost maps especially in 
large-scale networks.

I carried out some tests with path-vector cost maps based on our data. 
Our cost maps are already very large but path-vector maps are about 
three times larger (~50 MB vs. ~150 MB in uncompressed state). In 
average we have round about 4 hops between two PIDs which leads to an 
average path-vector of the same length. ECMP was not considered in the 
test but it will certainly further increase the size of the map.

Our idea to reduce cost map size is to provide topology information, 
e.g. with the property map presented in the unified-props draft, and let 
the client carry out the path determination. This means, the ALTO server 
provides the network, cost and property map to enable clients to get 
their desired level of detail for the path costs.

I also think this approach can coexist with path-vector cost maps. An 
ALTO server can provide both cost maps with and without path vector and 
a property map providing the topology. This way it is up to the client 
whether it wants to save bandwidth and invests some processing time to 
perform path determination by itself or it fetches the full path-vector 
cost map.

Any thoughts on this?

Cheers
Hans


On 01.08.2016 23:37, Vijay K. Gurbani wrote:
> Folks: As the (draft) minutes [1] of IETF 96 reflect, there was general
> consensus on adoption of path vector and routing state abstraction
> documents towards the charter deliverable of graph representation
> formats in ALTO.
>
> The chairs will like to start a call for adoption of the two documents
> --- https://tools.ietf.org/html/draft-yang-alto-path-vector-03 and
> https://tools.ietf.org/html/draft-gao-alto-routing-state-abstraction-03
> --- as deliverables towards the charter item.
>
> Note that there remains some ambiguity (in the chair's mind) on whether,
> once adopted, these will proceed as two drafts or whether they will be
> merged in one.  The authors of these drafts are urged to provide
> clarity on the evolution of these documents.
>
> The call for adoption runs for two weeks, from Mon Aug 1, 2016 to Mon
> Aug 15, 2016.  This will be a good time to comment on the list and
> inform the working group of any issues with adopting these items, or
> whether the working group was remiss in considering other documents.
> Please post to the list.  (Even a simple "I support these documents
> towards charter deliverable" is a good indication.)
>
> Thanks,
>
> [1] https://www.ietf.org/proceedings/96/minutes/minutes-96-alto
>
> - vijay