Subject: [ENUM] Comments to draft-ietf-enum-e164-gstn-np-00

From: "Rosbotham, Paul" <[email-masked]>
Date: Fri, 28 Jul 2000 10:30:18 +0100

I have a series of comments to the raft-ietf-enum-e164-gstn-np-00.

Firstly I believe it is a good summary of the NP issues.  I note it has an
ENUM reference, but I'm not sure that the subject matter is covered within
then ENUM remit, indeed the issues the document raise cut across many areas
of study.  However, I understand the logic of introducing the document to
ENUM given NP has arisen extensively in our discussions.

Some detailled comments;

Section 5.2 QoR
It could be instructive to add text to explain why this approach is adopted,
ie to reduce the number of queries that the originating network has to make
to the NPDB (for QoR number of queries = 1 per call to ported number, for
ACQ number of queries = 1 per call to any number, ported or not).

I believe there is an error on Figure 2 as Query on Release is abbreviated
to QoS.

Section 5.4 OR
"This scheme is also called Remote Call Forwarding. "
I would say that Onward Routeing and Remote Call Forward are quite
different.  The former uses [network] datafill on the switch to reroute
calls.  The latter is a stop-gap measure which essentially uses GSTN switch
customer features to forward calls.  I'm not a signalling expert, but I
don't believe RCF is totally transparent, and I don't think it could be used
to access "non-diallable" routeing numbers and modify NOA parameters etc.
I'd prefer if the sentence in question was removed.

Section 5.5 Comparisons of the Four schemes
You've wandered into a minefield here...
The sentences I would query are
"The OR scheme is the least efficient in terms of using the network
resources. " , and
"The ACQ scheme is the most efficient in terms of using the switching and
transmission facilities for the call."

I would not argue with the statements in the context of transmission.
However the situation with GSTN switches varies dramatically according to
individual manufacturer and architecture.  Some switches are optimised
around making external queries (ie IN) and hence are well suited to ACQ
approaches.  On some, however, a significant overhead is incurred in
carrying out an external database lookup (not all are so bad, but on some it
can be 30-40% overhead).  As such, to do this on all calls (ACQ) can require
substantial extra capacity on the GSTN switches, which can outstrip the
additional resources required to onward route the relatively small
percentage of calls that are to ported numbers.  In summary, your statements
are correct in the context of transmission, the situation is not so
clear-cut for switching facilities.

Section 7.2 paragraph
"Please note that all those enhancements are for national use. This is
because number portability is supported within a nation. Within each nation,
the telecommunications industry or the regulatory bodies can decide which
method or methods to use. Number portability related parameters and coding
are never passed across the national boundaries."

This is a very important para, and potentially deserves a section in its own
right.  It must be recognised that the modified parameters, routeing numbers
etc are in general not internationally significant so cannot work across
international boundaries.  In practical terms, whenever "originating
network" is referred to in NP, it means "the first network in the call path
in the country of the ported number".  This has profound implications for
the IP world where the concept of national differences doesn't normally
apply so much.

Section 8
Netherlands : QoS is referred to when I believe QoR is meant.  I believe
that in practical terms calls may be onward routed via KPN (although the
responsibility for routeing lies with the originator), but think it may be
worth checking this.
Spain : Same comment regards QoS/QoR.  Again, in practical terms calls are
onward routed via the donor (although the responsibility for routeing lies
with the originator).

General
There is a section 9 on how NP facilitates number pooling.  It may be worth
having a section on how NP facilitates the introduction of Individual Number
Assignment (ie the assignment of individual numbers to operators for onward
assignment to customers, or even assignment directly to customers, bypassing
operators)

Hope all this is of value,

Paul Rosbotham

Cable & Wireless Plc

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From: James Yu <[email-masked]>
Date: Fri, 28 Jul 2000 14:29:26 -0500

Paul,

Thanks for the good comments.  Please see the responses below.

James

> -----Original Message-----
> From: Rosbotham, Paul [mailto:[email-masked]]
> Sent: Friday, July 28, 2000 5:30 AM
> To: [email-masked]
> Subject: [ENUM] Comments to draft-ietf-enum-e164-gstn-np-00
> 
> 

Section 5.2 addresses the QoR scheme without any comments.  Your point on
the QoR scheme and the ACQ scheme can be found in the last paragraph of
Section 5.5 for ported numbers.  But it is certainly a good point to add a
discussion about the merit of not generating the NPDB queries for non-ported
numbers when using the QoR, dropback and OR schemes.

> I believe there is an error on Figure 2 as Query on Release 

Will correct.

> I'd prefer if the sentence in question was removed.

We'll remove the sentence.  In the U.S., it may be called Route Indexing
instead of Remote Call Forwarding.

> clear-cut for switching facilities.

The discussion in this section is about the number of the switches and
transmission facilities involved in the four schemes; however, however we
understand your point and will add appropriate wording to the next version
of the draft.

> the IP world where the concept of national differences 

Yes.  Since IP has no national boundaries, the IP networks may get the
"national" routing numbers via the NPDB queries and need to route the calls
via the IP networks to the terminating GSTN GWs.  So a mechanism in the IP
(e.g., "tel" URL) is needed to carry NP related information across the IP
network and "international" routing numbers may need to be carried and used
by the IP networks to route the calls and make the GSTN GW selection (e.g.,
TRIP).  draft-yu-tel-url-00.txt [TEL] was submitted on 7/11, which proposes
how the NP related information can be carried in the enhanced "tel" and
"fax" URLs. 

> 
> Section 8
> Netherlands : QoS is referred to when I believe QoR is meant. 

Will correct.

>  I believe

Will check.   All are welcomed to contact the authors for updating the
information that may be outdated, incomplete or incorrect.

> assignment to customers, or even assignment directly to 

We'll try to clarify that in the next version of the draft.