Subject: Re: [core] #241: Proxy Safe & Cache Key indication for options

From: "core issue tracker" <[email-masked]>
Date: Fri, 07 Sep 2012 10:56:42 -0000

#241: Proxy Safe & Cache Key indication for options

Comment (by zach@…):

 Consensus of IETF Vancouver WG meeting was:

 - Use the new option number encoding with Critial/Elective, Safe to
 Forward and Cache-key and re-number the options appropriately as presented
 by Carsten.

-- 
----------------------------------+--------------------------
 Reporter:  zach@…                |       Owner:  zach@…
     Type:  protocol enhancement  |      Status:  new
 Priority:  minor                 |   Milestone:  post-WGLC-1
Component:  coap                  |     Version:  coap-09
 Severity:  -                     |  Resolution:
 Keywords:                        |
----------------------------------+--------------------------

Ticket URL: <http://trac.tools.ietf.org/wg/core/trac/ticket/241#comment:7>
core <http://tools.ietf.org/core/>

---

From: "core issue tracker" <[email-masked]>
Date: Mon, 10 Sep 2012 08:35:00 -0000

Comment (by esko.dijk@…):

 Just noting that with Carsten's proposal, the section 5.4.1 defined
 behaviour is then only applicable to "non-proxying" endpoints. Proxies
 (which are also endpoints) have different rules using the Safe/Unsafe bit
 as in slide 21 of IETF84 presentation
 http://www.ietf.org/proceedings/84/slides/slides-84-core-0.pdf

Ticket URL: <http://trac.tools.ietf.org/wg/core/trac/ticket/241#comment:8>
core <http://tools.ietf.org/core/>

---

From: Zach Shelby <[email-masked]>
Date: Mon, 24 Sep 2012 14:06:02 +0300

Hi,

I have been working on integrating the Option re-numbering into coap-12, and have done an analysis based on the original proposal from Carsten presented in Vancouver. That proposal was already pretty good, but some adjustments were made to optimize for the most commonly used option combinations. Based on that optimization I am proposing the following numbering. This takes into account Critical, Unsafe and Cache-key encoding. This re-numbering requires the use of Jump only in a couple response combinations where there is no payload and when doing Proxy-Uri requests. In those situations overhead is not an issue as there is no payload in the message, so the extra byte from including a Jump is reasonable.

Attached is the spreadsheet that was used to calculate the option numbers, and check that the option combinations were optimal (avoiding Jump where possible). 

Note that also Observe and Block options are affected by the renumbering (and thus updated drafts will be submitted in conjunction with the coap-12 submission).

Zach

   +-----+---+---+---+----------------+--------+--------+-------------+
   | No. | C | U | R | Name           | Format | Length | Default     |
   +-----+---+---+---+----------------+--------+--------+-------------+
   |   1 | x |   | x | If-Match       | opaque | 0-8    | (none)      |
   |   2 |   | x |   | Max-Age        | uint   | 0-4    | 60          |
   |   3 | x | x |   | Uri-Host       | string | 1-255  | (see below) |
   |   4 | x |   |   | Content-Type   | uint   | 0-2    | (none)      |
   |   5 | x |   |   | If-None-Match  | empty  | 0      | (none)      |
   |   7 | x | x |   | Uri-Port       | uint   | 0-2    | (see below) |
   |   8 |   |   | x | ETag           | opaque | 1-8    | (none)      |
   |  11 | x | x | x | Uri-Path       | string | 0-255  | (none)      |
   |  12 |   |   | x | Accept         | uint   | 0-2    | (none)      |
   |  15 | x | x | x | Uri-Query      | string | 1-255  | (none)      |
   |  16 |   |   | x | Location-Path  | string | 0-255  | (none)      |
   |  19 | x | x |   | Token          | opaque | 1-8    | (empty)     |
   |  20 |   |   | x | Location-Query | string | 0-255  | (none)      |
   |  35 | x | x |   | Proxy-Uri      | string | 1-1034 | (none)      |
   +-----+---+---+---+----------------+--------+--------+-------------+

                    C=Critical, U=Unsafe, R=Repeatable

                             Table 1: Options

-- 
Zach Shelby, Chief Nerd, Sensinode Ltd.
http://www.sensinode.com
http://zachshelby.org  - My blog "On the Internet of Things"
http://6lowpan.net - My book "6LoWPAN: The Wireless Embedded Internet"
Mobile: +358 40 7796297

---

From: "core issue tracker" <[email-masked]>
Date: Mon, 24 Sep 2012 11:38:14 -0000

Changes (by zach@…):

 * status:  new => closed
 * resolution:   => fixed

Comment:

 Done in coap-12.

-- 
----------------------------------+--------------------------
 Reporter:  zach@…                |       Owner:  zach@…
     Type:  protocol enhancement  |      Status:  closed
 Priority:  minor                 |   Milestone:  post-WGLC-1
Component:  coap                  |     Version:  coap-09
 Severity:  -                     |  Resolution:  fixed
 Keywords:                        |
----------------------------------+--------------------------

Ticket URL: <http://trac.tools.ietf.org/wg/core/trac/ticket/241#comment:10>
core <http://tools.ietf.org/core/>