Re: Review of draft-ietf-nsis-qspec-18.txt

Jerry correctly describes the situation re: Y.2171 versus Y.1571. Here
are some additional clarifications:
 
1. The correct ITU-T Recommendation is Y.2171. Unfortunately, the ITU-T
initially assigned Y.1571 to this Recommendation; only later on they
changed it to Y.2171. So Y.1571 is not superseded by Y.2171; in fact
they are the same document.
 
2. The total number of priority levels has not changed in the ongoing
Recommendation number change. There have always been 3 levels.
 
3. The total number of priority levels were agreed to involving
extensive discussions with a number of major service providers. The
intent was to ensure that Priority Level 1 - the highest admission
control priority - was exclusively reserved for emergency
telecommunications. The discussions then focused on how many other
levels were needed. There was agreement that:
    - There is a broad class of traffic that can be considered "Best
Effort". This is priority level 3.
    - There is a broad class of traffic that was not as critical as
emergency telecommunications but required better than "Best Effort".
This is priority level 2.
Thus 3 broad levels were agreed upon. With one caveat for flexibility:
Individual provider domains are free to assign additional sub-levels of
priority within these broad priority levels. The choice is up to
individual provider domains.
 
4. The above agreements were reached as I stated with several large
service providers participating: AT&T, Verizon, British Telecom, France
Telecom, Deutsche Telekom, NTT, KoreaTel, ZTE, China Tel.
 
Here is the relevant Clause (Clause 6) from Y.2171:
 
--------------------
  

Recommendation for admission control priority levels


Three admission control priority levels are recommended for
telecommunications services seeking entry into NGN:

*        Priority level 1: Traffic with this priority level receives the
highest assurance for admission to the network. This level is reserved
for emergency telecommunications over NGN. 

*        Priority level 2: Traffic with this priority level will not
receive the same assurance for admission as that given to priority level
1 traffic, but will receive higher assurance for admission than that
given to priority level 3 traffic. Examples include real-time services
(VoIP, video), VPN and data services. The selection of this priority
level is expected to be determined by appropriate service level
agreements (SLA) between network operators and customers for the desired
service.

*        Priority level 3: Traffic with this priority level receives the
least assurance for admission to the network. Examples include
"traditional" Internet service provider (ISP) services (e-mail, web
surfing). The selection of this priority level is expected to be
determined by appropriate SLA agreements between network operators and
customers for the desired service. 

Each network operator may adopt additional priority levels. The total
number of admission control priority levels may be extended in the
future.

The choice of priority implementation mechanisms in the transport
stratum is up to the network operator.
 
--------------------
 
Thanks,
 
Percy

________________________________

From: Gerald Ash [mailto:[email protected]] 
Sent: Tuesday, February 26, 2008 5:39 PM
To: ken carlberg; nsis ((E-mail))
Cc: Jerry Ash; TARAPORE, PERCY S, ATTLABS; Francois Le Faucheur IMAP;
[email protected]
Subject: Re: [NSIS] Review of draft-ietf-nsis-qspec-18.txt


Ken,
 
> Jerry,
 
>> This is confusing to me because admission priority has nothing to do
with 
>> Y.1541.  Y.1541 is associated with the <Y.1541.QoS Class> field (see
Section 
>> 5.2.14 of the updated -19 QSPEC document or Section 6.2.14 of the 
>> current -18 QSPEC document).
 
> mea culpa!!!  in my ramblings, I meant Y.1571, so just swap all
reference of 
> Y.1541 with Y.1571 from my previous postings
 
There is no Y.1571, only Y.2171 (it was renumbered).
 
>> QSPEC admission priority is simply using the 3 priority levels
already 
>> standardized by Y.2171.  Admission priority is a generic concept, not

>> invented by the ITU, so this is not 'ITU admission priority', just
plain 
>> ole' admission priority.
 
> I beg to differ.  We are in agreement that admission priority is a
generic 
> concept, but in Section 6.2.9 of the QSPEC you have bound an Admission

> Priority field with pre-existing values defined in Y.1571  as written
in the 
> following:
> 
> High priority flows, normal priority flows, and best-effort priority
> flows can have access to resources depending on their admission
> priority value, as described in [Y.1571], as follows:
> 
> Admission Priority:
> 0 - best-effort priority flow
> 1 - normal priority flow
> 2 - high priority flow
> 
> And now we're told these values are to be updated by Y.2171.  By the
way, 
> could you tell us what these new values are?  Some of the members of
the 
> NSIS list are not members of the ITU, and so don't have that
information on 
> hand.
 
The values are unchanged.  There is no Y.1571, it was renumbered Y.2171,
the reference has been corrected in QSPEC -19.  
 
You don't have to be a member of ITU to get a recommendation, they are
all freely available on the www.itu.int web-site.  Y.2171 can be
downloaded at http://www.itu.int/rec/T-REC-Y.2171/en.  
 
BTW, essentially all service providers and equipment vendors belong to
and participate in the ITU.  All these service providers and equipment
vendors have unanimously agreed to Y.2171.

>> What's missing here is an explanation of what the approach is in 
>> [EMERGENCY-RSVP].  As I posted earlier in 
>> http://www.ietf.org/mail-archive/web/nsis/current/msg08231.html
<mhtml:{B096A9AC-8D5F-4D5A-AACE-EC56A1B5E65A}mid://00000015/!x-usc:http:
//www.ietf.org/mail-archive/web/nsis/current/msg08231.html> :

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