Network Working Group A. Yegin, Ed.
Internet-Draft Samsung AIT
Expires: August 11, 2005 E. Njedjou
France Telecom
S. Veerepalli
Qualcomm
N. Montavont
T. Noel
LSIIT - University Louis Pasteur
February 10, 2005
Link-layer Event Notifications for Detecting Network Attachments
draft-ietf-dna-link-information-01.txt
Status of this Memo
By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed,
and any of which I become aware will be disclosed, in accordance with
RFC 3668.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 11, 2005.
Copyright Notice
Copyright (C) The Internet Society (2005). All Rights Reserved.
Abstract
Certain network access technologies are capable of providing various
link-layer status information to IP. Link-layer event notifications
can help IP expeditiously detect configuration changes. This draft
Yegin, et al. Expires August 11, 2005 [Page 1]
Internet-Draft L2 Notifications for DNA February 2005
provides a non-exhaustive catalogue of information available from
well-known access technologies.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Requirements notation . . . . . . . . . . . . . . . . . . 4
2. Link-Layer Event Notifications . . . . . . . . . . . . . . . . 5
2.1 GPRS/3GPP . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 cdma2000/3GPP2 . . . . . . . . . . . . . . . . . . . . . . 7
2.3 IEEE 802.11/WiFi . . . . . . . . . . . . . . . . . . . . . 8
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
4. Security Considerations . . . . . . . . . . . . . . . . . . . 11
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1 Normative References . . . . . . . . . . . . . . . . . . . . 13
6.2 Informative References . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 15
A. Change History . . . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . 18
Yegin, et al. Expires August 11, 2005 [Page 2]
Internet-Draft L2 Notifications for DNA February 2005
1. Introduction
It is not an uncommon occurrence for a node to change its point-of
attachment to the network. This can happen due to mobile usage
(e.g., a mobile phone moving among base stations) or nomadic usage
(e.g., road-warrior case).
A node changing its point-of attachment to the network may end up
changing its IP subnet and therefore require re-configuration of
IP-layer parameters, such as IP address, default gateway information,
and DNS server address. Detecting the subnet change can usually use
network-layer indications such as a change in the advertised prefixes
(i.e., appearance and disappearance of prefixes). But generally
reliance on such indications does not yield rapid detection, since
these indications are not readily available upon node changing its
point of attachment.
The changes on the underlying link-layer status can be relayed to IP
in the form of link-layer event notifications. Establishment and
tear down of a link-layer connection are two basic events types.
Additional information can be conveyed in addition to the event type,
such as the identifier of the network attachment point, or
network-layer configuration parameters obtained via the link-layer
attachment process. It is envisaged that such event notifications
can in certain circumstances be used to expedite the inter-subnet
movement detection and reconfiguration process. For example, the
notification indicating that the node has established a new
link-layer connection can be used for immediately probing the network
for a possible configuration change. In the absence of such a
notification from the link-layer, IP has to wait for indications that
are not immediately available, such as receipt of next scheduled
router advertisement, unreachability of the default gateway, etc.
It should be noted that a link-layer event notification does not
always translate into a subnet change. Even if the node has torn
down a link-layer connection with one attachment point and
established a new connection with another, it may still be attached
to the same IP subnet. For example, several IEEE 802.11 access
points can be attached to the same IP subnet. Moving among these
access points does not warrant any IP-layer configuration change.
In order to enable an enhanced scheme for detecting change of subnet,
we need to define link-layer event notifications that can be
realistically expected from various access technologies. The
objective of this draft is to provide a catalogue of link-layer
events and notifications in various architectures. While this
document mentions the utility of this information for detecting
change of subnet (or, detecting network attachment - DNA), the
Yegin, et al. Expires August 11, 2005 [Page 3]
Internet-Draft L2 Notifications for DNA February 2005
detailed usage is left to other documents, namely DNA solution
specifications.
The document limits itself to the minimum set of information that is
necessary for solving the DNA problem [I-D.ietf-dna-goals]. A
broader set of information may be used for other problem spaces
(e.g., anticipation-based Mobile IP fast handovers
[I-D.ietf-mobileip-lowlatency-handoffs-v4]
[I-D.ietf-mipshop-fast-mipv6]). Separate documents that are
backward-compatible with this one can be generated to discuss further
enhancements.
These event notifications are considered with hosts in mind, although
they may also be available on the network side (e.g., on the access
points and routers). An API or protocol-based standard interface may
be defined between the link-layer and IP for conveying this
information. That activity is beyond the scope of this document.
1.1 Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Yegin, et al. Expires August 11, 2005 [Page 4]
Internet-Draft L2 Notifications for DNA February 2005
2. Link-Layer Event Notifications
Link-layer event notifications are considered to be one of the inputs
to the DNA process. A DNA process is likely to take other inputs
(e.g., presence of advertised prefixes, reachability of default
gateways) before determining whether IP-layer configuration must be
updated. It is expected that the DNA process can take advantage of
link-layer notifications when they are made available to IP. While
by itself a link-layer notification may not constitute all the input
DNA needs, it can at least be useful for prompting the DNA process to
collect further information (i.e., other inputs to the process). For
example, the node may send a router solicitation as soon as it learns
that a new link-layer connection is established.
Two basic link-layer events are considered potentially useful to DNA
process: link up and link down. Both of these events are
deterministic, and their notifications are provided to IP-layer after
the events successfully conclude. These events and notifications are
associated with a network interface on the node. The IP module may
receive simultaneous independent notifications from each one of the
network interfaces on the node.
Node's establishment of a link-layer connection with an attachment
point that signifies the availability of IP service (i.e., being able
to send and receive IP packets) between the two is considered a link
up event. The attachment point is typically an access network
element, such as an access point, a base station, or a wired switch
[TO-DO: How about ad-hoc networks? Attached neighbors may be
considered attachment points].
The actual event is managed by the link-layer of the node through
execution of link-layer protocols and mechanisms. Once the event
successfully completes within the link-layer, its notification must
be delivered to the IP-layer. By the time the notification is
delivered, the link-layer of the node must be ready to accept IP
packets from the IP and the physical-layers.
Link down event signifies the discontinuation of the IP service
between the node and the attachment point. When the link-layer
connection is physically or logically torn down and it can no longer
carry IP packets, this is considered to be a link down event.
Among these two events the first one to take place after an interface
becomes enabled must be a link up event. During the time a network
interface is enabled, it may go through a series of link up and down
events. Each time the interface changes its point of attachment, a
link down event with the previous attachment point must be followed
by a link up event with the new one. Finally, when the network
Yegin, et al. Expires August 11, 2005 [Page 5]
Internet-Draft L2 Notifications for DNA February 2005
interface is disabled, this must generate a link down event. Each
one of these events must generate a notification in order they occur.
A node may have to change its IP-layer configuration even when the
link-layer connection stays the same. An example scenario is the
IPv6 subnet renumbering [RFC2461]. Therefore, there exists cases
where IP-layer configuration may have to change even without the
IP-layer receiving a link up notification. Therefore, a link-layer
notification is not a mandatory indication of a subnet change.
In addition to the type of the event (link up, link down), a
link-layer notification may also optionally deliver information
relating to the attachment point. Such auxiliary information may
include identity of the attachment point (e.g., base station
identifier), or the IP-layer configuration parameters associated with
the attached subnet (e.g., subnet prefix, default gateway address,
etc.). While merely knowing that a new link-layer connection is
established may prompt DNA process to immediately seek other clues
for detecting network configuration change, auxiliary information may
constitute further clues (and even the final answers sometimes). In
cases where there is a one-to-one mapping between the attachment
point identifiers and the IP-layer configurations, learning the
former can reveal the latter. Furthermore, IP-layer configuration
parameters obtained during link-layer connection may be exactly what
the DNA process is trying to discover (e.g., IP address configured
during PPP link establishment).
The link-layer process leading to a link up or link down event
depends on the link technology. While a link-layer notification must
always indicate the event type, the availability and types of
auxiliary information on the attachment point depends on the
link-layer technology as well. The following subsections examine
three link-layer technologies and describe when a link-layer
notification must be generated and what information must be included
in it. The coverage on the link types may be expanded in the future
[TO-DO: Add IEEE 802.3].
2.1 GPRS/3GPP
GPRS is an enhancement to the GSM data transmission architecture and
capabilities, designed to allow for packet switching in user data
transmission within the GPRS network as well as for higher quality of
service for the IP traffic of Mobile Terminals with external Packets
Data Networks such as the Internet or corporate LANs
[GPRS][GPRS-LINK].
The GPRS architecture consists of a Radio Access Network and a packet
domain Core Network.
Yegin, et al. Expires August 11, 2005 [Page 6]
Internet-Draft L2 Notifications for DNA February 2005
- The GPRS Radio Access Network is composed of Mobile Terminals (MT),
a Base Station Subsystem and Serving GPRS Support Nodes (SGSN).
- An IP Core Network that acts as the transport backbone of user
datagrams between SGSNs and Gateway GPRS Support Nodes (GGSN). The
GGSN ensures the GPRS IP core network connectivity with external
networks, such as Internet or Local Area Networks. GGSN acts as the
default IP gateway for the MT.
A GPRS MT that wants to establish IP-level connections should first
perform a GPRS attach to the SGSN. This should be followed by a
request the GPRS network to settle the necessary soft state mechanism
(GPRS tunneling protocol) between its serving SGSN and the GGSN. The
soft state maintained between the MT, the SGSN and the GGSN is called
a PDP Context. It is used for guaranteeing a negotiated quality of
service for the IP flows exchanged between the GPRS MT and an
external Packet Data Network such as Internet . It is only after the
PDP Context has been established, address autoconfiguration and
tunneling mechanism have taken place that the MT's IP packets can be
forwarded to and from its remote IP peers. The aim of PDP Context
establishment is also to provide IP-level configuration on top of the
GPRS link-layer attachment.
Successful establishment of a PDP Context on a GPRS signifies the
availability of IP service to the MT. Therefore, this link-layer
event must generate a link up event notification sent to IP-layer.
With IPv4, the auxiliary information carried along with this
notification MUST be the IPv4 address of the MT which is obtained as
part of the PDP Context. With IPv6, the PDP Context activation
response does not come along with a usable IPv6 address.
Effectively, the IPv6 address received from the GGSN in the PDP
address field of the message does not contain a valid prefix. The MN
actually only uses the interface-identifier extracted from that field
to form a link-local address, that it uses afterwards to obtain a
valid prefix (e.g., by stateless [RFC2462][GPRS-CN] or stateful
[RFC3315][GPRS-GSSA] address configuration). Therefore no
IPv6-related auxiliary information is provided to IP-layer.
Similarly, PDP Context deactivation must generate a link down event
notification.
2.2 cdma2000/3GPP2
cdma2000-based 3GPP2 packet data services provide mobile users wide
area high-speed access to packet switched networks [CDMA2K]. Some of
the major components of the 3GPP2 packet network architecture consist
of:
Yegin, et al. Expires August 11, 2005 [Page 7]
Internet-Draft L2 Notifications for DNA February 2005
- Mobile Station (MS), which allows mobile access to packet-switched
networks over a wireless connection.
- Radio Access Network, which consists of the Base Station
Transceivers, Base Station Controllers, and the Packet Control
Function.
- Network Access Server known as the Packet Data Switching Node
(PDSN). The PDSN also serves as default IP gateway for the IP MS.
3GPP2 networks use the Point-to-Point Protocol (PPP [RFC1661]) as the
link-layer protocol between the MS and the PDSN. Before any IP
packets may be sent or received, PPP must reach the Network-Layer
Protocol phase, and the IP Control Protocol (IPCP [RFC1332], IPV6CP
[RFC2472]) reach the Opened state. When these states are reached in
PPP, a link up event notification must be delivered to the IP-layer.
When the PPP is used for 3GPP2 Simple (i.e., non-Mobile) IPv4
Service, IPCP enables configuration of IPv4 address on the MS. This
IPv4 address must be provided as the auxiliary information along with
the link up notification. IPV6CP used for Simple IPv6 service does
not provide an IPv6 address, but the interface-identifiers for local
and remote end-points of the PPP link. Since there is no
standards-mandated correlation between the interface-identifier and
other IP-layer configuration parameters, this information is deemed
not useful for DNA (hence it is not provided as auxiliary
information).
IPCP/IPV6CP termination, or the underlying LCP or NCP reaching Closed
State signify the end of corresponding IP service on the PPP link.
This event must generate a link down notification delivered to the
IP-layer.
2.3 IEEE 802.11/WiFi
IEEE 802.11-based WiFi networks are the wireless extension of the
Local Area Networks. Currently available standards are IEEE 802.11b
[IEEE-802.11b], IEEE 802.11g [IEEE-802.11g], and IEEE 802.11a
[IEEE-802.11a]. The specifications define both the MAC-layer and the
physical-layer. The MAC layer is the same for all these
technologies.
Two operating modes are available in the IEEE 802.11 series, either
infrastructure mode or ad-hoc mode. In infrastructure mode, all
link-layer frames are transmitted to an access point (AP) which then
forwards them to the final receiver. A STA must establish a IEEE
802.11 link with an AP in order to send and receive IP packets. In a
WiFi network that supports Robust Secure Network (RSN
Yegin, et al. Expires August 11, 2005 [Page 8]
Internet-Draft L2 Notifications for DNA February 2005
[IEEE-802.11i]), successful completion of 4-way handshake between the
STA and AP commences the availability of IP service. The link up
event notification must be generated upon this event. In
non-RSN-based networks, successful association or re-association
events on the link-layer must cause a link up notification sent to
the IP-layer.
As part of the link establishment, Basic Service Set Identification
(BSSID) and Service Set Identifier (SSID) associated with the AP is
learned by the STA. BSSID is a unique identifier of the AP. Its
value is set to the MAC address of the AP. SSID carries the
identifier of the Extended Service Set (ESS) - the set composed of
APs and associated STAs that share a common distribution system.
BSSID and SSID should be provided as auxiliary information along with
the link up notification. Unfortunately this information does not
provide a deterministic indication of whether the IP-layer
configuration must be changed upon movement. There is no
standards-mandated one-to-one relation between the BSSID/SSID pairs
and IP subnets. An AP with a given BSSID can connect a STA to any
one of more than one IP subnets. Similarly, an ESS with the given
SSID may span multiple IP subnets. And finally, the SSIDs are not
globally unique. The same SSID may be used by multiple independent
ESSs. See Appendix A of [DNA4] for a detailed discussion.
Nevertheless, BSSID/SSID information may be used in a probabilistic
way by the DNA process, hence it is provided with the link up event
notification.
Disassociation event in RSN-based, and de-authentication and
disassociation events in non-RSN-based WiFi networks must translate
to link down events, and generate the corresponding link-layer
notifications.
In ad-hoc mode, mobile station (STA) in range may directly
communicate with others, i.e., without any infrastructure or
intermediate hop. The set of communicating STAs is called IBSS for
Indepedant Basic Service Set. In an IBSS, only station services are
available, i.e. authentication, deauthentication, privacy and MSDU
delivery. STAs do not associate with each other, and therefore may
exchange data frames in state 2 (authenticated and not associated) or
even in state 1 (unauthenticated and unassociated) if authentication
is not used. Although a link up indication can be generated upon
authentication, one may not be present per latter usage. If
authentication is performed, a deauthentication event is used for
generating the link down indication. Concerning the link layer
identification, both the BSSID (which is a random MAC address chosen
by a STA of the IBSS) and SSID may be used to identify a link, but
not to make any assumptions on the IP network configuration.
Yegin, et al. Expires August 11, 2005 [Page 9]
Internet-Draft L2 Notifications for DNA February 2005
3. IANA Considerations
This document has no actions for IANA.
Yegin, et al. Expires August 11, 2005 [Page 10]
Internet-Draft L2 Notifications for DNA February 2005
4. Security Considerations
A faked link-layer event notification can be used to launch a
denial-of service attack on the node and the associated network.
Secure generation and delivery of these notifications must be
ensured. This is a subject for link-layer and network stack designs
and therefore it is outside the scope of this document.
Yegin, et al. Expires August 11, 2005 [Page 11]
Internet-Draft L2 Notifications for DNA February 2005
5. Acknowledgements
The authors would like to acknowledge Bernard Aboba, Sanjeev Athalye,
JinHyeock Choi, Greg Daley, Pekka Nikander, and Muhammad Mukarram bin
Tariq for their useful comments and suggestions.
Yegin, et al. Expires August 11, 2005 [Page 12]
Internet-Draft L2 Notifications for DNA February 2005
6. References
6.1 Normative References
[CDMA2K] "IS-835 - cdma2000 Wireless IP Network Standard", .
[GPRS] "Digital cellular telecommunications system (Phase 2+);
General Packet Radio Service (GPRS) Service description;
Stage 2", 3GPP 3GPP TS 03.60 version 7.9.0 Release 98.
[GPRS-LINK]
"Digital cellular telecommunications system (Phase 2+);
Radio subsystem link control", 3GPP GSM 03.05 version
7.0.0 Release 98.
[I-D.ietf-dna-goals]
Choi, J., "Detecting Network Attachment in IPv6 Goals",
draft-ietf-dna-goals-04 (work in progress), December 2004.
[IEEE-802.11a]
Institute of Electrical and Electronics Engineers, "IEEE
Std 802.11a-1999, supplement to IEEE Std 802.11-1999, Part
11: Wireless MAN Medium Access Control (MAC) and Physical
Layer (PHY) specifications: High-speed Physical Layer in
the 5 GHZ band", IEEE Standard 802.11a, September 1999.
[IEEE-802.11b]
Institute of Electrical and Electronics Engineers, "IEEE
Std 802 Part 11, Information technology -
Telecomunications and information exchange between systems
- Local and metropolitan area networks - Specific
requirements - Part 11: Wireless Lan Medium Access Control
(MAC) And Physical Layer (PHY) Specifications", IEEE
Standard 802.11b, August 1999.
[IEEE-802.11g]
Institute of Electrical and Electronics Engineers, "IEEE
Std 802.11g-2003, Amendment to IEEE Std 802.11, 1999
edition, Part 11: Wireless MAN Medium Access Control (MAC)
and Physical Layer (PHY) specifications. Amendment 4:
Further Higher Data Rate Extension in the 2.4 GHz Band",
IEEE Standard 802.11g, June 2003.
[IEEE-802.11i]
Institute of Electrical and Electronics Engineers, "Draft
Supplement to STANDARD FOR Telecommunications and
Information Exchange between Systems - LAN/MAN Specific
Requirements - Part 11: Wireless Medium Access Control
Yegin, et al. Expires August 11, 2005 [Page 13]
Internet-Draft L2 Notifications for DNA February 2005
(MAC) and physical layer (PHY) specifications:
Specification for Enhanced Security", IEEE Draft 802.11I/
D8, February 2004.
[RFC1332] McGregor, G., "The PPP Internet Protocol Control Protocol
(IPCP)", RFC 1332, May 1992.
[RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,
RFC 1661, July 1994.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2462] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
[RFC2472] Haskin, D. and E. Allen, "IP Version 6 over PPP", RFC
2472, December 1998.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and
M. Carney, "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, July 2003.
6.2 Informative References
[GPRS-CN] "Technical Specification Group Core Network;
Internetworking between the Public Land Mobile Network
(PLMN) supporting packet based services and Packet Data
Networks (PDN) (Release 6)", 3GPP 3GPP TS 29.061 version
6.1.0 2004-06.
[GPRS-GSSA]
"Technical Specification Group Services and System Aspect;
General Packet Radio Service (GPRS) Service description;
Stage 2 (Release 6)", 3GPP 3GPP TS 23.060 version 6.5.0
2004-06.
[I-D.ietf-mipshop-fast-mipv6]
Koodli, R., "Fast Handovers for Mobile IPv6",
draft-ietf-mipshop-fast-mipv6-03 (work in progress),
October 2004.
[I-D.ietf-mobileip-lowlatency-handoffs-v4]
Malki, K., "Low latency Handoffs in Mobile IPv4",
draft-ietf-mobileip-lowlatency-handoffs-v4-09 (work in
progress), June 2004.
[RFC2461] Narten, T., Nordmark, E. and W. Simpson, "Neighbor
Yegin, et al. Expires August 11, 2005 [Page 14]
Internet-Draft L2 Notifications for DNA February 2005
Discovery for IP Version 6 (IPv6)", RFC 2461, December
1998.
Authors' Addresses
Alper E. Yegin (editor)
Samsung Advanced Institute of Technology
75 West Plumeria Drive
San Jose, CA 95134
USA
Phone: +1 408 544 5656
EMail: alper.yegin@samsung.com
Eric Njedjou
France Telecom
4, Rue du Clos Courtel BP 91226
Cesson-SȨvignȨ, 35512
France
Phone: +33 299124202
EMail: eric.njedjou@france-telecom.com
Siva Veerepalli
Qualcomm
5775 Morehouse Drive
San Diego, CA 92131
USA
Phone: +1 858 658 4628
EMail: sivav@qualcomm.com
Nicolas Montavont
LSIIT - University Louis Pasteur
Pole API, bureau C428
Boulevard Sebastien Brant
Illkirch, 67400
France
Phone: +33 390 244 587
EMail: montavont@dpt-info.u-strasbg.fr
Yegin, et al. Expires August 11, 2005 [Page 15]
Internet-Draft L2 Notifications for DNA February 2005
Thomas Noel
LSIIT - University Louis Pasteur
Pole API, bureau C428
Boulevard Sebastien Brant
Illkirch, 67400
France
Phone: +33 390 244 592
EMail: noel@dpt-info.u-strasbg.fr
Yegin, et al. Expires August 11, 2005 [Page 16]
Internet-Draft L2 Notifications for DNA February 2005
Appendix A. Change History
The following changes were made on draft version 00:
- IEEE 802.11 ad-hoc mode discussion added.
- IPv6 address configuration over 3GPP networks clarified.
Yegin, et al. Expires August 11, 2005 [Page 17]
Internet-Draft L2 Notifications for DNA February 2005
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Yegin, et al. Expires August 11, 2005 [Page 18]
