INTERNET DRAFT JUNHYUK SONG
March 2002 SAMSUNG ELECTRONICS
DONGKIE LEE
SK TELECOM
DNS RR type for NAI
draft-song-dnsext-nai-support-01.txt
Status of This Memo
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Abstract
This document proposes the use of the new DNS RR type "NAI"
(Network Access Identifier) [RFC2486] to specify dynamically assigned
IP address.
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1. Introduction
The use of the wireless mobile networking has been dramatically
increased thanks to rapid development of wireless technology and
commercial deployment of Mobile IP technology [RFC3220].
The most recent release of Mobile IPv4 supports the dynamic Home
Address assignment mechanism that allow MN (Mobile Node) being
identified by NAI (Network Access Identifier) [RFC2486] rather than
static Home IP address. NAI has a prominent role on the mobile
network environment. This is not only because NAI significantly
reduces the IPv4 address shortage problem and but also it provides
the standardized method for identifying users in order to accomplish
the interoperability for roaming over multiple ISPs (Internet Service
Providers).
The most of the Mobile IPv4 deployment including 3GPP2 CDMA2000
wireless packet data system architecture [P.S0001-B] identify
the Mobile Node by NAI. Therefore the need for standardized method
of binding the ever changing home address of the MN over various ISPs
to NAI is necessary.
The DNS basically provides a mechanism to map between hostnames and
IP address with support of many other RRs thorough hierarchically
built domain names. The NAI is of the form user@realm [RFC2486].
Adding NAI as a DNS RR shall enable tracking of the dynamically
changed home IP address. This document specifies a new RR type for
NAI, mapping host IP address and user identifier (NAI) [RFC2486].
2. Applicability Statement
Mobile IPv4 is designed to provide the IP mobility that provides
reasonably seamless IP connectivity. Since the MN (Mobile Node) is
no longer necessarily identified by the unique home IP address,
the mechanism for the locating and updating newly assigned home IP
address is required [UM].
The NAI RR defines user identifier, NAI widely used for PPP dialup
connection and Mobile IPv4. The basic idea is to let mobile Internet
user to constantly update its IP address, while moving around
multiple access provider network. It can enables correspondent user
to always reach the specific user by querying NAI to name server,
regardless of the connecting location.
It is expected that NAI RR will be used in IRS(Internet Reachability
Service) of 3GPP2 wireless IP network standard [P.S0001-B]
(see Appendix A).
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The applications that running on the Dynamic Home Address Allocation
enabled Mobile IPv4 MN (Mobile node) depends on the one to one
mapping of NAI and newly assigned mobile host IP address in DNS name
server for the connectivity with Correspondent nodes.
Because it will be the only way the CN (Correspondent Node) can find
the Mobile Node's newly assigned IP address. An example of
application is including WWW server, IP push service, Instant
Messaging, Multi-user Network games, Multi-chat, etc.
3. NAI RR Type
NAI name space is resemble to Domain Name Space, except that it is a
sequence of one or more labels, made of the user identifier and
domain name. The "@" sign before realm, shall be treated as a
delimiter to flag user ID part. Every user Identifier
shall end with "@" sign and placed before domain name. NAI records
cause no additional section processing
The NAI record has the DNS RR type of "?", hence has the same QTYPE
number of "?". Note NAI RR requires IANA number assignment.
The class of NAI RR is defined in the IN class only.
TTL should be configured to minimize the time of the RR being cached
The RDATA of NAI is same as A RDATA format, 32 bit Internet Address
4. Examples
Resource Record for NAI(junhyuk@xbs.samsung.co.kr) is like below:
junhyuk@.xbs.samsung.co.kr. 1440 IN NAI 165.213.221.4
5. IANA Considerations
It requires new RR type number from IANA.
6. Acknowledgements
Special thanks to Professor Murali Venkatesh of Syracuse University
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Appendix A. IRS of 3GPP2 wireless IP Network standard
In this example, I've omitted the detail operation of deleting
DNS record in case of user disconnect. In IRS, it is assumed that
MS desires to be reached by a fixed identifier such as an NAI-like
hostname
1. Simple IP operation
Upon connecting to new access network MS(Mobile Station) shall
generate CHAP authentication with NAI for user authentication.
After successfully authenticate the user authentication request,
AAAH shall send DNS A record update message to name server.
(See figure 1)
+--------------+ PPP CHAP (3) +--------------+
| | Auth Req | AAAH |
| AAAF |-------------->| |
| |<--------------| |
+--------------+ PPP CHAP(5) +--------------+
^ | Auth Ack |
PPP CHAP | | User |
Auth Req | | PPP CHAP Location |
(2) | | Auth Ack Update(4)|
| | (6) v
| v +---------------+
+------+ PPP CHAP +-----------+ | Name Server |
| | Auth Req (1) | | +---------------+
| |---------------------->| PDSN | ^
| |<----------------------| | User |
| MS | PPP CHAP | | Location |
| | Auth Ack (7) | | Query |
| |<--------------------->| | |
| | IP data (8) | | +-------+
+------+ | | <-----------| CH |
+-----------+ IP data +-------+
Figure 1: Simple IPv4 operation
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2. Mobile IP operation
When the HA receives and successfully replies to an initial Mobile IP
Registration Request, it performs the DNS update for the MS if it has
previously received an indication from the home RADIUS server to do
so, or has otherwise been provisioned to do so. The HA shall send a
DNS Update message [RFC 2136] to the DNS server to add a Resource
Record for the MS, if so required by the home RADIUS server [4].
(See figure 2)
+--------------+ +--------------+
| |---------------->| |
| AAAF | | AAAH |
| |<----------------| |
+--------------+ +--------------+
^ | ^
Access | | Access |
Request | v Accept v
+------+ Agent +--------------+ +--------------+
| |Advertisement | | | |
| | with FAC | PDSN/FA | | Mobile IPv4 |
| MS |<------------ | | | Home Agent |
| |------------> | |---------------->| |
| |Mobile IP RRQ | |Mobile IP RRQ | |
| |with MN-AAA | | | |
| |<-------------| |<----------------| |
+------+Mobile IP RRP +--------------+Mobile IP RRP +--------------+
|
User |
Location |
Update |
v
+--------------+
| Name Server |
+--------------+
Figure 2: Mobile IPv4 operation
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References
[RFC3220] C. Perkins, Editor. "IP Mobility Support". RFC 3320.
January 2002.
[UM] J.H Song, DK Lee "draft-song-network-user-mobility-00.txt"
Work in Progress
[RFC2486] Bernard Aboba and Mark A. Beadles "The Network Access
Identifier". RFC 2486. January 1999.
[P.S0001-B] 3GPP2 P.S0001-B work in progress.
ftp://ftp.3gpp2.org/TSGP/Standard/
Addresses
Questions about this memo can be directed to the authors:
JUNHYUK SONG
SAMSUNG ELECTRONICS.
Packet Technology System Lab.
Mobile Development Team
Phone: +82-31-279-3639
Email: junhyuk@telecom.samsung.co.kr
santajunman@yahoo.com
DONGKIE LEE
SK TELECOM
Core Network Development Team
Network R&D Center
Phone +82-2-829-4640
Email: galahad@netsgo.com
FAX:+82-2-829-4612
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