Re: [alto] ALTO Extension: Defining a Cost Metrics document?

[Qin Wu <[e-mail]>]

From: [e-mail] [mailto:[e-mail]] On Behalf Of Y. Richard Yang
Sent: Monday, October 14, 2013 7:20 AM
To: IETF ALTO
Cc: [e-mail]; Qin Wu
Subject: [alto] ALTO Extension: Defining a Cost Metrics document?

Dear all,

I am reading up on the documents that define cost metrics.

The motivation is that the base ALTO protocol (http://www.ietf.org/id/draft-ietf-alto-protocol-20.txt) has defined only one Cost Metric: 'routingcost':

- Defined the semantics at Sec. 6.1.1.1 of , and then listed it at Table 3.

- Used "hopcount" in examples of Sec. 9.2.3 and 9.2.4, but the semantics of not formally defined.

Given the aforementioned state of the base protocol, I see good value in that the WG produces a WG document that defines a relatively complete set of Cost Metrics.

I particular, I read the following:

- http://tools.ietf.org/html/draft-lee-alto-app-net-info-exchange-02
  (Sec. 3.4 introduced three metrics: hopcount, latency, pktcost, and cost)

- http://tools.ietf.org/html/draft-wu-alto-json-te-01
  Defined a set of metrics: in Sec. 4. This work, as stated in the document, is motivated by

- http://www.ietf.org/id/draft-ietf-ospf-te-metric-extensions-04.txt

During the review of ALTO base protocol, we are suggested to document performance metrics (cost metrics) per the guideline of
- RFC 6390 Guidelines for Considering New Performance Metric Development. A. Clark, B. Claise. October 2011. (Format: TXT=49930 bytes) (Also BCP0170) (Status: BEST CURRENT PRACTICE)

Here a first question, I have, is whether the authors will produce a "simple" document, at the upcoming IETF, whose only purpose is to:

  define a set of cost metrics, including the nameing, the semantics, ... following the guideline per RFC 6390, that can benefit the base protocol.

[Qin] This is exactly what I we are doing in draft-wu-alto-json-te. We are checking if we can give a complete list of cost metrics that are built based on

draft-ietf-idr-ls-distribution-03,RFC5305, draft-wu-idr-te-pm-bgp<http://tools.ietf.org/id/draft-wu-idr-te-pm-bgp-02.txt>,draft-ietf-ospf-te-metric-extensions-04, draft-ietf-isis-te-metric-extensions-01.

We will further generalize them to firstly have some base metrics that can applied either to the whole path or any link in the path and then have

Derived metrics that are link specific.



The update (v-02) will come in a few days.


I feel that such a document is focused, and has good value by itself.

The implications of the introducing multiple cost metrics can be explored in another document, which I will send in another email shortly.

Thanks.

Richard