Internet Draft RJ Atkinson
draft-irtf-rrg-ilnp-arp-00.txt Consultant
Expires: 13 JUL 2012 SN Bhatti
Category: Experimental U. St Andrews
13 January 2012
ARP Extension for ILNPv4
draft-irtf-rrg-ilnp-arp-00.txt
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Internet Draft ILNPv4 13 JAN 2012
documents at any time. It is inappropriate to use Internet-Drafts
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The list of current Internet-Drafts can be accessed at
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The list of Internet-Draft Shadow Directories can be accessed at
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This document is not on the IETF standards-track and does not
specify any level of standard. This document merely provides
information for the Internet community.
This document is part of the ILNP document set, and has had
extensive review within the IRTF Routing Research Group. ILNP is
one of the recommendations made by the RG Chairs. Separately,
various refereed research papers on ILNP have also been published
during this decade. So the ideas contained herein have had much
broader review than the IRTF Routing RG. The views in this
document were considered controversial by the Routing RG, but the
RG reached a consensus that the document still should be
published. The Routing RG has had remarkably little consensus on
anything, so virtually all Routing RG outputs are considered
controversial.
Abstract
This document defines an Address Resolution Protocol (ARP)
extension to support ILNP for IPv4 (ILNPv4). ILNP is is an
experimental, evolutionary enhancement to IP. This document is a
product of the IRTF Routing RG.
Table of Contents
1. Introduction.............................
2. ARP Extension for ILNPv4.................
3. Security Considerations..................
4. IANA Considerations......................
5. References...............................
1. INTRODUCTION
The Identifier Locator Network Protocol (ILNP) is an proposal for
evolving the Internet Architecture. It differs from the current
Internet Architecture primarily by deprecating the concept of an
IP Address, and instead defining two new objects, each having
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crisp syntax and semantics. The first new object is the Locator, a
topology-dependent name for a subnetwork. The other new object is
the Identifier, which provides a topology-independent name for a
node.
1.1 ILNP Document Roadmap
The ILNP Architecture document [ILNP-ARCH] is the best place to
start reading about ILNP. ILNP has multiple instantiations.
[ILNP-ENG] discusses engineering and implementation aspects common
to all instances of ILNP. This document discusses engineering and
implementation details that are specific to ILNP for IPv4
(ILNPv4). [ILNP-DNS] describes new Domain Name System (DNS)
resource records used with ILNP. [ILNP-ICMPv4] defines the ICMP
Locator Update message used with ILNPv4. [ILNP-v4opts] defines new
IPv4 options for use with ILNPv4. Other documents describe ILNP
for IPv6 (ILNPv6) [ILNP-ICMPv6] [ILNP-NONCE6].
1.2 Terminology
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 RFC 2119. [RFC-2119]
2. ARP Extensions for ILNPv4
ILNP for IPv4 (ILNPv4) is merely a different instantiation of the
ILNP architecture, so it retains the crisp distinction between the
Locator and the Identifier. As with ILNPv6, only the Locator
values are used for routing and forwarding ILNPv4 packets
[ILNP-ARCH]. As with ILNP for IPv6 (ILNPv6), when ILNPv4 is used
for a network-layer session, the upper-layer protocols (e.g.
TCP/UDP pseudo-header checksum, IPsec Security Association) bind
only to the Identifiers, never to the Locators [ILNP-ENG].
However, just as the packet format for IPv4 is different to IPv6,
so the engineering details for ILNPv4 are different also. While
ILNPv6 is carefully engineered to be fully backwards-compatible
with IPv6 Neighbor Discovery, ILNPv4 relies upon an extended
version of the Address Resolution Protocol (ARP) which is defined
here. While ILNPv4 could have been engineered to avoid changes in
ARP, that would have required that the ILNPv4 Locator (i.e. L32)
have slightly different semantics, which was architecturally
undesirable.
The packet formats used are direct extensions of the existing
widely deployed ARP Request (Opcode 1) and ARP Reply (Opcode 2)
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packet formats. This design was chosen for practical engineering
reasons (i.e. to maximise code reuse), rather than for maximum
protocol design purity.
We anticipate that ILNPv6 is much more likely to be widely
implemented and deployed than ILNPv4. However, having a clear
definition of ILNPv4 helps demonstrate the difference between
architecture and engineering, and also demonstrates that the
common ILNP architecture can be instantiated in different ways
with different existing network-layer protocols.
2.1 ILNPv4 ARP Request Packet Format
The ILNPv4 ARP Request (OP code XXX) is an extended version of the
widely deployed ARP Request (Opcode 1). This extension permits the
node's Identifier (I) values to be carried in the ARP message, in
addition to the node's 32-bit Locator (L32) values [ILNP-DNS].
0 7 15 23 31
+--------+--------+--------+--------+
| HT | PT |
+--------+--------+--------+--------+
| HAL | PAL | OP |
+--------+--------+--------+--------+
| S_HA (bytes 0-3) |
+--------+--------+--------+--------+
| S_HA (bytes 4-5)|S_L32 (bytes 0-1)|
+--------+--------+--------+--------+
|S_L32 (bytes 2-3)|S_I64 (bytes 0-1)|
+--------+--------+--------+--------+
| S_I64 (bytes 2-5) |
+--------+--------+--------+--------+
|S_ID (bytes 6-7) | T_HA (bytes 0-1)|
+--------+--------+--------+--------+
| T_HA (bytes 3-5) |
+--------+--------+--------+--------+
| T_L32 (bytes 0-3) |
+--------+--------+--------+--------+
| T_I64 (bytes 0-3) |
+--------+--------+--------+--------+
| T_I64 (bytes 4-7) |
+--------+--------+--------+--------+
Figure 2.1: ILNPv4 ARP Request packet format
In the diagram of Fig 2.1, the fields are as follows:
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HT Hardware Type (same as for ARP; unchanged)
PT Protocol Type (same as for ARP; unchanged)
HAL Hardware Address Length (same as for ARP; unchanged)
PAL Protocol Address Length (uses new value 12)
OP Operation Code (uses new value XXX)
S_HA Sender Hardware Address (same as for ARP; unchanged)
S_L32 Sender L32 (same as Sender IPv4 address for ARP)
S_I64 Sender Identifier (8 bytes)
T_HA Target Hardware Address (same as for ARP; unchanged)
T_L32 Target L32 (same as Target IPv4 address for ARP)
T_I64 Target Identifier (8 bytes)
The changed OP code indicates that this is ILNPv4 and not IPv4.
The semantics and usage of the ILNPv4 ARP Request are identical to
the existing ARP Request (Opcode 2), except that the ILNPv4 ARP
Request is sent only by nodes that support ILNPv4.
2.2 ILNPv4 ARP Reply Packet Format
The ILNPv4 ARP Reply (OP code YYY) is an extended version of the
widely deployed ARP Reply (OP code 2). This extension permits the
node's Identifier (I) values to be carried in the ARP message, in
addition to the node's 32-bit Locator (L32) values [ILNP-DNS].
0 7 15 23 31
+--------+--------+--------+--------+
| HT | PT |
+--------+--------+--------+--------+
| HAL | PAL | OP |
+--------+--------+--------+--------+
| S_HA (bytes 0-3) |
+--------+--------+--------+--------+
| S_HA (bytes 4-5)|S_L32 (bytes 0-1)|
+--------+--------+--------+--------+
|S_L32 (bytes 2-3)|S_I64 (bytes 0-1)|
+--------+--------+--------+--------+
| S_I64 (bytes 2-5) |
+--------+--------+--------+--------+
|S_ID (bytes 6-7) | T_HA (bytes 0-1)|
+--------+--------+--------+--------+
| T_HA (bytes 3-5) |
+--------+--------+--------+--------+
| T_L32 (bytes 0-3) |
+--------+--------+--------+--------+
| T_I64 (bytes 0-3) |
+--------+--------+--------+--------+
| T_I64 (bytes 4-7) |
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+--------+--------+--------+--------+
Figure 2.2: ILNPv4 ARP Reply packet format
In the diagram of Fig 2.2, the fields are as follows:
HT Hardware Type (same as for ARP; unchanged)
PT Protocol Type (same as for ARP; unchanged)
HAL Hardware Address Length (same as for ARP; unchanged)
PAL Protocol Address Length (uses new value 12)
OP Operation Code (uses new value YYY)
S_HA Sender Hardware Address (same as for ARP; unchanged)
S_L32 Sender L32 (same as Sender IPv4 address for ARP)
S_I64 Sender Identifier (8 bytes)
T_HA Target Hardware Address (same as for ARP; unchanged)
T_L32 Target L32 (same as Target IPv4 address for ARP)
T_I64 Target Identifier (8 bytes)
The changed OP code indicates that this is ILNPv4 and not IPv4.
The semantics and usage of the ILNPv4 ARP Reply are identical to
the existing ARP Reply (Opcode 2), except that the ILNPv4 ARP
Reply is sent only by nodes that support ILNPv4.
2.3 Operation and Implementation of ARP for ILNPv4
The operation of ARP for ILNPv4 is almost identical to that for
IPv4. Essentially, the key difference is:
a) where an IPv4 ARP Request would use IPv4 addresses, an
ILNPv4 ARP Request would use:
1. a 32-bit L value (_L32 suffixes in Figs 2.1 & 2.2)
2. a 64-bit I value (_I64 suffixes in Figs 2.1 & Fig 2.2)
b) where an IPv4 ARP Reply would use IPv4 addresses, an
ILNPv4 ARP Reply would use:
1. a 32-bit L value (_L32 suffixes in Figs 2.1 & 2.2)
2. a 64-bit I value (_I64 suffixes in Figs 2.1 & Fig 2.2)
As the OP codes XXX and YYY are distinct from ARP for IPv4, but
the packet formats are Figs 2.1 and 2.2 are, effectively, extended
versions of the corresponding ARP packets, it should be possible
to implement this extension of ARP by extending additional ARP
code rather than having to write new code.
3. SECURITY CONSIDERATIONS
Security considerations for the overall ILNP Architecture are
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described in [ILNP-ARCH]. Additional common security
considerations applicable to ILNP are described in [ILNP-ENG].
This section describes security considerations specific to the
specific ILNPv4 topics discussed in this document.
The existing widely deployed Address Resolution Protocol (ARP) for
IP version 4 (IPv4) is a link-layer protocol, so it is not
vulnerable to off-link attackers. In this way, it is a bit
different than IPv6 Neighbor Discovery; IPv6 ND is a subset of the
Internet Control Message Protocol (ICMP), which runs over the
Internet Protocol version 6 (IPv6).
However, ARP does not include any form of authentication, so
current ARP deployments are vulnerable to a range of attacks from
on-link nodes. For example, it is possible for one node on a link
to forge an ARP packet claiming to be from another node, thereby
"stealing" the other node's IPv4 address. [RFC-5227] both
describes several of these risks and also describes some measures
that an ARP implementation can use to reduce the chance of
accidental IPv4 address misconfiguration and also to detect such
misconfiguration if it should occur.
This extension does not change the security risks that are
inherent in using ARP.
For additional protection against on-link attackers, especially in
high-risk operational environments, implementation and use of the
IEEE standards for link-layer security [IEEE-802.1-AE] are
recommended.
4. IANA CONSIDERATIONS
In accordance with [RFC-5494], IANA is requested to assign new
Operation Codes in the Address Resolution Protocol Parameters
registry to the "ILNPv4 ARP Request" message (with value XXX
above) and to the "ILNPv4 ARP Reply" message (with value YYY)
above.
5. REFERENCES
This document has both Normative and Informational References.
5.1 Normative References
[ILNP-ARCH] R. Atkinson and S. Bhatti, "ILNP Architecture",
draft-irtf-rrg-ilnp-arch, January 2012.
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[ILNP-ENG] R. Atkinson and S. Bhatti, "ILNP Engineering
Considerations", draft-irtf-rrg-ilnp-eng, January 2012.
[ILNP-DNS] R. Atkinson and S. Bhatti, "DNS Resource Records
for ILNP", draft-irtf-rrg-ilnp-dns, January 2012.
[ILNP-ICMPv4] R. Atkinson and S. Bhatti, "ICMP Locator Update
message for ILNPv4", draft-irtf-rrg-ilnp-icmpv4,
January 2012.
[ILNP-v4opts] R. Atkinson and S. Bhatti, "IPv4 Options for
ILNPv4", draft-irtf-rrg-ilnp-v4opts, January 2012.
[RFC-2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14, RFC 2119,
March 1997.
[RFC-5227] S. Cheshire, "IPv4 Address Conflict Detection",
RFC-5227, July 2008.
[RFC-5494] J. Arkko & C. Pignataro, "IANA Allocation Guidelines
for the Address Resolution Protocol", RFC-5494,
April 2009.
[IEEE-802.1-AE] IEEE, "Media Access Control (MAC) Security",
IEEE Standard 802.1 AE, 18 August 2006, IEEE,
New York, NY, 10016, USA.
5.2 Informative References
[ILNP-NONCE6] R. Atkinson and S. Bhatti, "ILNPv6 Nonce
Destination Option", draft-irtf-rrg-ilnp-noncev6,
January 2012.
[ILNP-ICMPv6] R. Atkinson and S. Bhatti, "ICMPv6 Locator
Update Message for ILNPv6",
draft-irtf-rrg-ilnp-icmpv6, January 2012.
ACKNOWLEDGEMENTS
Steve Blake, Mohamed Boucadair, Noel Chiappa, Steve Hailes, Joel
Halpern, Mark Handley, Volker Hilt, Paul Jakma, Dae-Young Kim,
Tony Li, Yakov Rehkter and Robin Whittle (in alphabetical order)
provided review and feedback on earlier versions of the ILNP
document set. Steve Blake provided an especially thorough review
of an earlier version of the entire ILNP document set, which was
extremely helpful. We also wish to thank the anonymous reviewers
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for their feedback.
AUTHOR'S ADDRESS
RJ Atkinson
Consultant
San Jose, CA,
95125 USA
Email: rja.lists@gmail.com
SN Bhatti
School of Computer Science
University of St Andrews
North Haugh, St Andrews
Fife, Scotland
KY16 9SX, UK
Email: saleem@cs.st-andrews.ac.uk
Expires: 13 JUL 2012
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