Subject: [IPTEL] [TRIP] Address Families in draft-ietf-iptel-trip-03

From: James Yu <[email-masked]>
Date: Fri, 4 Aug 2000 10:35:37 -0500

Hussein,

Section 5.1.1 of TRIP defines two address families, One for POTS numbers and
the other for routing numbers. Since TRIP deals with "routing," it is
suggested that only the "routing numbers" address family is used.  This will
avoid the handling of two address families in TRIP for supporting number
portability (NP).  The basic rule is:  
(1) Use the "routing number" for routing (e.g., check against the TRIP
routing table) if both the "routing number" and "POTS number" are present.
(2) Use the "POTS number" for routing if "routing number" is not present.

The reasons are described below.

- For countries such as U.S. and Canada that support NP and use routing
numbers that overlap with the POTS numbers (e.g., the same format and
length), and use the POTS numbers as the routing numbers for non-ported POTS
numbers, the "routing number" address family is sufficient for call routing.

 * For a ported-out number, a location routing number (LRN) is retrieved
from the NP database.   That LRN (plus the country code if required) is used
for routing.
 * For a non-ported number, that POTS number is used for routing because its
prefix (e.g., the first 6 digits of the national number) can identify the
donor switch that serves this non-ported number.  The POTS numbers in this
case are actually treated as the routing numbers!  For example, if the POTS
number is 202-533-1234 and is not ported, a LRN of 202-533-0000 can be used
as the LRN for routing the call.  Use of "202-533-1234" or "202-533-0000"
does not make any difference because the GSTN switches in the North America
routes national calls based on the first 6 digits of the national POTS
numbers.  That is why the POTS numbers are used for routing for non-ported
numbers.  
  So all we need is the "routing number" address family.  If the routing
number is present, it is used to check against the TRIP routing table.  If
it is not present, the POTS number is used to check against the TRIP routing
table.  Only one TRIP routing table is needed.  We only need to use the
"correct" number to check against the TRIP routing table if both the routing
number and POTS number are present.
  
- For countries such as Austria and Belgium that support NP and concatenate
a routing prefix (called network routing number) with the POTS number (e.g.,
Cxxxx+POTS number in Belgium), it does not matter whether we view this
"concatenated number" as a routing number or POTS number if we only use
"routing numbers" address family.  The TRIP table will contain Cxxxx
prefixes and also regular POTS prefixes.  So if the called party number does
not contain the routing prefix, the POTS routing prefixes are checked for
routing.  But if it contains the routing prefix such as Cxxxx, the Cxxxx
prefixes in the same routing table are checked for routing.  The key point
is that only one TRIP routing table is needed. 

- For countries that do not support NP, the POTS numbers can be viewed as
the routing numbers.  So we still have just one TRIP routing table/address
family.

Please note that the routing number will not contain digit F that was
pointed out by Monika Muench in  an earlier e-mail discussion (I'm not sure
whether it was posted to iptel or sip discussion list). 

James

James Yu
Principal Technical Industry Liaison
NeuStar Inc.
1120 Vermont Avenue, NW,
Suite 550
Washington, D.C. 20005
USA
+1-202-533-2814 (B)
+1-202-533-2976 (Fax)
+1-202-256-1200 (Mobile)
[email-masked]
http://www.neustar.com

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From: "Hussein F. Salama" <[email-masked]>
Date: Tue, 08 Aug 2000 18:43:30 -0700

James,

We decided to define two address families, and not just one as your
suggesting, for the foloowing reasons:
- In order to perform aggregation we need to know when we have all
possible next characters. Routing numbers have a different character set
than other POTS numbers, and hence the need for defining a dedicated
address family for routing numbers.
- Other reasons concern the nature of routing numbers:
	* they don't represent destinations
	* their scope is limited to national boundaries

Regarding the digit 'F' are suggesting that we remove it from the
character set of routing numbers, because it will never be used? 

Hussein

-- 
Hussein F. Salama
Cisco Systems
Mail Stop SJC6/3, 170 W. Tasman Drive, San Jose, CA 95134
Voice: +1 (408) 527-7147, Fax: +1 (408) 527-1714

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From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 08 Aug 2000 22:01:51 -0400

>         * their scope is limited to national boundaries

I agree. Also note that TRIP might be used to represent routes to
gateways which don't have ss7 access to the PSTN; they are simply
connected through PRI or T1 or whatever. For such gateways, the prefixes
to which the gateway can route are limited to only pots numbers, as
these are the only ones exposed through these interfaces.

-Jonathan R.

-- 
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
http://www.dynamicsoft.com