Re: [alto] Review of draft-lcsr-alto-service-functions

[LUIS MIGUEL CONTRERAS MURILLO <[e-mail]>]

Hi Qin,

Thanks for the comments and questions.

Please, see in-line

Best regards

Luis

De: Qin Wu <[e-mail]>
Enviado el: miércoles, 13 de julio de 2022 5:57
Para: LUIS MIGUEL CONTRERAS MURILLO <[e-mail]>
CC: [e-mail]; [e-mail]
Asunto: Review of draft-lcsr-alto-service-functions

Hi, Luis:
Thank for your proposed new draft on service function handling (https://datatracker.ietf.org/doc/draft-lcsr-alto-service-functions/), I believe it is related to service function invocation use case. Thanks for that.
ALTO Path vector seems a good basis for your requested protocol extension.
One thing I am not very clear is
1.who will be the client to consume ALTO information combining network topo info and service function information?
[Luis>>] We can consider two kind of use cases: (1) the need for determining path characteristics to an instance of a SF, or (2) the same but for a service chain.
In the case of (1), the client of ALTO information can be the entity in charge of determining the steering towards a function, then deciding between multiple instances what is the optimal one according to some metrics (less hops, a certain delay or BW -according to ALTO performance metrics-, etc). This can be done for a single SF instance, or recursively, to identify the optimal instances for composing a service chain.
In the case of (2) the client could essentially determine the more convenient chain (assuming it is already formed)
Clients of this could be either the SFC Classifier [RFC7665] or the SFC Controller [draft-ietf-sfc-control-plane-08], the controller/PCE that could set up a chain based on SR / SRv6 [draft-ietf-spring-sr-service-programming], the MANO and/or WIM in ETSI NFV architecture for interconnecting deployed VNFs [ETSI GR NFV-SOL 017], the 3GPP management system e.g. for selecting among distributed UPFs, etc.

Should it be cross domain service orchestration system, or ingress node or headend?
[Luis>>] What I have in mind is the client being an orchestrator or alike, either internal or external to IETF context. The consideration of ingress node is interesting to take, thanks for pointing this out. Food for thought.
2.How does such client consume these information?
[Luis>>] In my view, the consumption of the information will be similar as ALTO clients do today. That is, taking ALTO outcome as an informed raking of alternatives that can be further processed together with other information on the hands of the client, to perform the optimal selection from the client's perspective. Does it make sense?

-Qin

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