Re: [alto] ALTO recharter: proposed item - General ALTO protocol extensions

["Randriamasy, Sabine (Nokia - FR/Paris-Saclay)" <[e-mail]>]

Dear all,

The paragraph below is proposed to define the WG item on "general protocol extensions".
As the purpose of this work item is also to support other WG items that may need these extensions, your feedback again is more than welcome.
Thanks,
Sabine

General protocol extensions to convey a richer set of cost attributes allowing to determine not only "where" and "when" to connect but also under which conditions. Such additional information will be related both to entities (e.g. conveying time-averaged (cache storage capacities and)  server load in data center supported applications) and to ALTO path costs (e.g. ALTO path cost value depending on conditions such as real-time network indications or SLA or policy or access-type or indicator type).

The working group will specify such extension in coordination with both other ALTO working group items and IETF working groups that have a focus on the related use cases.  The scope of extensions is not limited to those identified by the WIs and WGs, but is limited by the criteria set out below.
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From: alto <[e-mail]> On Behalf Of Randriamasy, Sabine (Nokia - FR/Paris-Saclay)
Sent: Tuesday, November 10, 2020 7:24 PM
To: IETF ALTO <[e-mail]>
Subject: [alto] ALTO recharter: proposed item - General ALTO protocol extensions

Dear all,

Please find below a WG item proposal for "general ALTO protocol extensions", on which your feedback and suggestions will be more than welcome.
Thanks,
Sabine

---------- Context: the current ALTO charter
o Extends the path cost values in several directions:
              - single to array of several cost metrics => allows apps to decide upon several metrics and make decision compromise
              - single cost value to array if time dependent cost values => allow apps to determine when to connect
o Extends endpoints to entities on which properties are defined

---------- Basic Issues
+++  Issue 1: Some path cost values may depend on "contextual parameters" such as access type, SLA, policy or other indicators provided by network. In particular:
              - There may be different possible paths between source and destination, where some paths may or may not meet Application QoE or policy constraints. The Applications would like to see which path is most suitable.
              - Contextual parameters may be available at frequencies that are different from ALTO information frequency. For example, Cost on PID-Cell1 may differ, depending on some real-time network parameter value.

+++ Issue 2: Some entities may have properties whose values change over time. For instance, ANEs may have time-varying properties on cloud or networking resources

---------- Potential solution(s)
+++  To address issue 1 and related : extend cost attributes towards conditional values and parameters allowing a better interpretation of the received values
- Extension from single cost value to array of values dependent on context parameters:
allowing applications to make context-dependent decisions,
allowing also to combine information generated with different time dynamics, (freshness)
See examples on https://datatracker.ietf.org/doc/slides-98-alto-alto-cost-context/

+++  To address issue 2:
- ALTO Property Calendars to extend a single property value to an array of time-dependent property values

---------- Remaining issues to be addressed
- How to define cost value attributes?
- How to achieve a light and flexible design?
- How to moderate additional Server workload and ALTO traffic increase?

---------- Who will work on it, rough planning
+++  Extensions may go in standalone documents and/or extend existing ones, eg ALTO performance metrics
+++ Contributors: Sabine and any other interested people
+++ Plans for IETF 110:
              -  Reactivation and update of related existing ALTO drafts
              -  First draft for ALTO Property Calendars