Transcript Understanding ENUM & Current Status

Understanding ENUM
&
Current Status
[email protected]
Network Planning
August 21, 2001
Understanding ENUM & Current Status
ACRONYMS
A Record
ARPA
DNS
E.164
IETF
ITU
MGC
NAPTR
NS
RTP
SG
SGA
SIP
URI
August 21, 2001
(A host Address)
(Advanced Research Project Administration)
(Domain Name Server)
(ITU telephone numbering plan)
(Internet Engineering Task Force)
(International Telecommunication Union)
(Media Gateway Controller)
(Naming Authority Pointer Record in a DNS)
(Authoritative Name Server, DNS record)
(Real-Time Transport Protocol)
(Signaling Gateway)
(Study Group A of the International Telecommunication
Advisory Committee, US policy and regulatory aspects
telecommunications services.)
(Session Initiation Protocol)
(Uniform Resource Identifiers)
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Understanding ENUM & Current Status
DNS Hierarchy
The root node
""
e164.arpa
...
.com
.arpa
in-addr
second-level node
third-level node
1.e164.arpa
.net
second-level node
second-level node
third-level node
7.1.e164.arpa
...
1.2.3.4.5.5.5.2.3.7.1.e164.arpa
This slide is from draft 4 of the Ad-Hoc Study Group A report on ENUM
August 21, 2001
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Understanding ENUM & Current Status
TIER 0, I, & II
Tier 0
e164.arpa
Tier I
1.e164.arpa
Tier II
.1.e164.arpa
Directs the DNS query to the controlling country based
on country code. This is done by providing the NS record
of Tier I.
Tier I directs the DNS query to the customer Tier II provider.
The NS record is provided for the subscriber’s telephone
number.
DNS service that stores a list of service specific internet
addresses in the form of URI’s in a DNS resource record
called NAPTR. TIER II will return the full list of Internet
addresses associated with the E.164 number being queried.
IN
IN
IN
IN
IN
August 21, 2001
NAPTR
NAPTR
NAPTR
NAPTR
NAPTR
10
10
10
10
10
10
10
10
10
10
"u"
"u"
"u"
"u"
"u"
"sip+E2U"
"mailto+E2U"
”fax+E2U"
”print+E2U"
"tel+E2U"
“!^.*$!sip:[email protected]!”
“!^.*$!mailto:[email protected]!”
“!^.*$!mailto:[email protected]!”
“!^.*$!mailto:[email protected]!”
“!^.*$!tel:+19135551212!”
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Understanding ENUM & Current Status
Example
Requestor types into their browser a E.164 number:
+19135551212
The requestor’s software converts the phone number
With country code into a ENUM ready number.
2.1.2.1.5.5.5.3.1.9.1.e164.arpa
Requestor
The Root
Node
Tier 0
Tier I
Tier II
August 21, 2001
.
e164.arpa
1.e164.arpa
.1.e164.arpa
The root node is the root server that directs queries to the
appropriate zone. .arpa, .com, .org, etc
Tier 0 database will direct the request to the North
American Tier I database(s) based on the country code of 1.
(Assumes specific model for Tier I.)
The Tier I database, for country code 1, could be two sub-tiers;
one sub-tier to receive country code 1 and the other to segment
the NPAs within North America. The NPAs could be grouped by
individual countries within North America.
The Tier II database will return to the requesting computer
the list of service specific addresses (URIs) associated with the
queried number.
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Understanding ENUM & Current Status
Example Continued
.
FAX
e164.arpa
1.e164.arpa
In this continued example, a requesting computer
can deliver information to several devices just by
knowing a phone number. This could be a number
from a business card. Now the user can send
information to a business associate based on the
options returned by the query.
.1.e164.arpa
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Understanding ENUM & Current Status
TIER 0 – II DATABASES
Tier 0:
 Only one database controlled by RIPE NCC and ITU (policy only)
 Contains participating country codes.
Tier I:
 Within North America there could be several Tier 1 databases.
 There would have to be a delegation process from the North American
country code of 1 to a NPA sub-database. The NPAs could be grouped by
individual countries in North America.
 Contains the fully qualified E.164 numbers and pointers to Tier II provider
for the subscribers URIs.
Tier II:
 Competitive with many Tier II providers
 Hosting the subscriber’s URIs
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Understanding ENUM & Current Status
Countries Covered by the North American Code of 1 (One)
United States
Canada
Jamaica
Bahamas
Grenada
Barbados
Barbuda & Antigua
St. Kitts & Nevis
St. Lucia
St. Vincent & the Grenadines
Dominica
Trinidad & Tobago
Dominican Republic
Anguilla
Bermuda
British Virgin Islands
Cayman Islands
Commonwealth of the Northern Mariana Islands
Guam
Montserrat
Puerto Rico
Turks & Caicos Islands
US Virgin Islands
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Understanding ENUM & Current Status
Problem

More then one Country under the 1 code for North America

Who will administer the Tier I database for North America?

What happens if one of the other countries within North America respond to the ITU
before the United States and are granted provisioning rights to the North American
Code of 1?

Do we want to be involved with all the other Countries in North America for ENUM
deployment?
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Understanding ENUM & Current Status
A Better Approach
.1.e164.arpa
United States NPAs
.1.e164.arpa
Canada NPAs
.1.e164.arpa
Jamaica NPA
.e164.arpa
Tier 0 (Containing list of country codes)
1.e164.arpa
Tier I for North America (Containing NPA pointers
for each country that is a subset of the 1 code)
.1.e164.arpa
Dominica NPA
.1.e164.arpa
Barbuda & Antigua
NPA
.1.e164.arpa
Barbados NPA
.1.e164.arpa
Grenada NPA
…..
.1.e164.arpa
ETC
Tier I+(subset) would allow each
country in North America to manage
their own Tier I equivalent database.
Any Tier II
Provider
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Understanding ENUM & Current Status
A Better Approach

Allows each country in North America to maintain their own Tier I equivalent
database.

Reflects the fact that the United States is not the only entity within the 1 (one) code.

Once routed to the individual country Tier I database, the subscriber’s phone
number and not the NPA will determine the Tier II provider for NAPTER records.
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Understanding ENUM & Current Status
ENUM enables PSTN to SIP calls
ENUM
Signaling
Gateway
STP
4
Invite
3
Invite
User A
1
Proxy
Server A
MGC
Invite: 19135551212
From: 12025551212
SSP
2
ENUM
Server
21215553191.e164.arpa
5
SIP: [email protected]
6
Proxy
Server B
Media
Gateway
Invite
8
7 Invite: SIP:
[email protected]
From: 12025551212
User B
In this example, User A attempts to contact User B who is on a VoIP network and uses a SIP phone.
1.
User A dials the global E.164 number for User B.
2.
The SSP sends an IAM message via SS7 to a SG (which is part of the Media Gateway Controller / Media
Gateway).
3.
The Media Gateway Controller sends an invite message to the nearest Proxy Server.
4.
Proxy Server A does not know User B address; therefore it contacts an ENUM Server.
5.
The ENUM Server returns the address of User B.
6.
Proxy A sends invite message to User B’s Proxy Server B
7.
Proxy Server B passes the invite to User B
8.
If User B accepts the call, there is a two-way RTP path established between User B and the Media
Gateway controller. A two-way path is also established between the Media Gateway and User A. At this
point User A is able to communicate with User B.
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Understanding ENUM & Current Status
Competitive Model – Advantages & Disadvantages
Advantages:

Any DNS provider can set up ENUM like structure in any Top Level Domain.

The DNS provider could provide all Tiers, 0 – II, and possibly root.
 Provide Registrar Functions
 Provide Register Functions

Can offer ENUM services outside of the United States.
Disadvantages:

Will require clients and non-client to have resolver software.

Performance issues are a concern for clients and none clients

Major performance concerns for VoIP providers when ENUM is used as a location
server.

Not compliant with RFC2916 from the IETF.

Not supported by the ITU-T Study Group 2.
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Understanding ENUM & Current Status
Status on ENUM
 US Department of State Ad-Hoc Study Group A on ENUM
 Completed recommendation to Department of State.
 Document Released on July 6.
 Presentation given to Study Group A on July 31.
 Recommendations






Recommendation for US participation in ENUM.
Provides guidance to respond to ITU.
Use the single zone per RFC 2916 (.arpa).
Understand that there will be competitive models deployed.
ENUM is an Opt In service.
Privacy Protection is a high priority.
 Scheduled Events
 August 27: First face-to-face meeting of the new ENUM Forum
 Agree to forum principles and procedures
 Agree to work plan
 Pick leaders for the 5 proposed subcommittees.
 September 4: Next Study Group 2 ITU-T meeting.
August 21, 2001
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