Re: [alto] General comment about draft-penno-alto-protocol-03.txt

["Y. Richard Yang" <[e-mail]>]

Hi Martin,

I really need to say that this is an excellent, fundamental comment!

Let me start with your second comment ("Second, I couldn't really find 
out what parts are from the various other incorporated protocols ..."). 
In this sense, we have succeeded in achieving seamless integration :-) 
 From the start,  it is clear to multiple authors of multiple proposals 
that there is not an inherent conflict of the many proposals. There is 
much synergy, in terms of service model, among many proposals already (I 
remember saying this at last IETF :-). The presentation slides listed 
key features of contributing proposals, and you can see large overlap. 
During our merge, we made an effort to *not* do a non-overlapping 
partition of ideas to different previous proposals.
As someone working on P4P, I would say that the current design has 
improved substantially over original P4P both in terms of service model 
and protocol. Designers of other contributing proposals sure can share 
how they think the current design improves over their previous 
proposals. Let me list some key *protocol/implementation* features that 
substantially improved over the very original P4P design and thus show 
the benefits. Of course, this list is my personal opinion and is by no 
means complete:

- A general, flexible protocol framework (e.g., server capability query 
as some kind of negotiation, generic endpoint property, reverse map) for 
extension
- XML protocol encoding for flexibility
- HTTP caching
- Possibility of batched distribution of ALTO info, for example, as a file

As a general rule, I feel that protocol design should be flexible, 
extensible, and consider implementation efficiency. Many good ideas of 
contributing proposals are reflected in the current, merged design, IMHO :-)

In terms of service model, you raised an excellent point as well. I see 
two basic service models in terms of providing path rating service:

- Network location map (clustering) to (implicitly) indicate 
coarse-grained proximity/preference (i.e., if same location, then it is 
preferred); preferred by some ISPs such as China Telecom as a starting 
point;

- Explicit rating of communication patterns: even here it can provide 
info in two ways (batched cost map or ranking list).

It is amazing to see that the preceding service models integrated quite 
cleanly in the current design without loss or substantial complexity. So 
I worry less about losing functionality, but more about providing 
guidelines to ISPs on how to use the ALTO service in their scenarios. 
Clearly a use-case document can be helpful.

Again, thank you so much for the excellent comment!

Richard

Martin Stiemerling wrote:
> Hi all,
>
> I have a general comment about draft-penno-alto-protocol-03.txt after reading it and some more  comments:
>
> The draft tries to incorporates now all other in parallel existing approaches (i.e., P4P, ALTO Info Export, Query/Response, ATTP, and Proxidor) but without any major discussion about the usefulness of this. All approaches have their pros and cons, and they are quite different ways of tackling with ALTO. The discussion about the various proposal just started and IMHO it was not clear which of the many does actually address the general challenges of ALTO. 
>
> This means (taking some as example):
> - P4P addresses the challenges out of the P4P project, which the specific mechanics of Comcast and Pando. I do see the value of P4P, but it is one case how you could do it, i.e., I'm not saying that this is bad. I like the approach very much. However, I do not (yet) see the evidence that P4P works for tracker-less P2P and in other deployments, even though most of the people believe this. 
>
> - Proxidor has a different view IMHO to ALTO, i.e., very operator driven. By solely integrating this, there might be a loss of functionality, e.g., Proxidor works also tracker-less p2p.
>
> - ATTP was a bit orthogonal to the other approaches and less to do with ALTO (even though it is related).
>
>
> Second, I couldn't really find out what parts are from the various other incorporated protocols, other than this looks as an evolved P4P proposal without explicitly saying what the benefits of the merger from the various protocols are.
>
> The protocol claims to "At the same time, it introduces additional techniques  to address potential scalability and privacy issues." (first paragraph, 2nd sentence of Section 2). However, I'm clueless after reading what these techniques are and why they're not discussed in the security section (privacy as term pops up in this sentence, and nowhere else).
>
> Thanks,
>
>   Martin
>
>
> [e-mail]
>
> NEC Laboratories Europe - Network Research Division
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