Internet DRAFT - draft-irtf-rrg-ilnp-arp
draft-irtf-rrg-ilnp-arp
Internet Draft RJ Atkinson
draft-irtf-rrg-ilnp-arp-07.txt Consultant
Expires: 10 JAN 2013 SN Bhatti
Category: Experimental U. St Andrews
10 JUL 2012
ARP Extension for ILNPv4
draft-irtf-rrg-ilnp-arp-07.txt
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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/1id-abstracts.html
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
At present, the Internet research and development community are
exploring various approaches to evolving the Internet
Architecture to solve a variety of issues including, but not
limited to, scalability of inter-domain routing [RFC4984]. A wide
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range of other issues (e.g. site multi-homing, node multi-homing,
site/subnet mobility, node mobility) are also active concerns at
present. Several different classes of evolution are being
considered by the Internet research & development community. One
class is often called "Map and Encapsulate", where traffic would
be mapped and then tunnelled through the inter-domain core of the
Internet. Another class being considered is sometimes known as
"Identifier/Locator Split". This document relates to a proposal
that is in the latter class of evolutionary approaches.
The Identifier Locator Network Protocol (ILNP) is a 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
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
This document describes describes extensions to ARP for use with
ILNPv4.
The ILNP architecture can have more than one engineering
instantiation. For example, one can imagine a "clean-slate"
engineering design based on the ILNP architecture. In separate
documents, we describe two specific engineering instances of
ILNP. The term ILNPv6 refers precisely to an instance of ILNP that
is based upon, and backwards compatible with, IPv6. The term ILNPv4
refers precisely to an instance of ILNP that is based upon, and
backwards compatible with, IPv4.
Many engineering aspects common to both ILNPv4 and ILNPv6 are
described in [ILNP-ENG]. A full engineering specification for
either ILNPv6 or ILNPv4 is beyond the scope of this document.
Readers are referred to other related ILNP documents for details
not described here:
a) [ILNP-ARCH] is the main architectural description of ILNP,
including the concept of operations.
b) [ILNP-ENG] describes engineering and implementation
considerations that are common to both ILNPv4 and ILNPv6.
c) [ILNP-DNS] defines additional DNS resource records that
support ILNP.
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d) [ILNP-ICMPv6] defines a new ICMPv6 Locator Update message
used by an ILNP node to inform its correspondent nodes
of any changes to its set of valid Locators.
e) [ILNP-NONCEv6] defines a new IPv6 Nonce Destination Option
used by ILNPv6 nodes (1) to indicate to ILNP correspondent
nodes (by inclusion within the initial packets of an ILNP
session) that the node is operating in the ILNP mode and
(2) to prevent off-path attacks against ILNP ICMP messages.
This Nonce is used, for example, with all ILNP ICMPv6
Locator Update messages that are exchanged among ILNP
correspondent nodes.
f) [ILNP-ICMPv4] defines a new ICMPv4 Locator Update message
used by an ILNP node to inform its correspondent nodes
of any changes to its set of valid Locators.
g) [ILNP-v4OPTS] defines a new IPv4 Nonce Option used by ILNPv4
nodes to carry a security nonce to prevent off-path attacks
against ILNP ICMP messages and also defines a new IPv4
Identifier Option used by ILNPv4 nodes.
h) [ILNP-ADV] describes optional engineering and deployment
functions for ILNP. These are not required for the operation
or use of ILNP and are provided as additional options.
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 [RFC2119].
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
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with IPv6 Neighbor Discovery, ILNPv4 relies upon an extended
version of the Address Resolution Protocol (ARP) [RFC826] 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 (OP code 1) and ARP Reply (OP code 2)
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 is an extended version of the widely
deployed ARP Request (OP code 1). For experimentation purposes,
the ILNPv4 ARP Request OP code uses decimal value 24. It is
important to note that decimal value 24 is a pre-defined,
shared-use experimental OP code for ARP [RFC5494], and is not
uniquely assigned to ILNPv4 ARP Requests. The ILNPv4 ARP Request
extension permits the Node's Identifier (NID) 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_NID (bytes 0-1)|
+--------+--------+--------+--------+
| S_NID (bytes 2-5) |
+--------+--------+--------+--------+
|S_ID (bytes 6-7) | T_HA (bytes 0-1)|
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+--------+--------+--------+--------+
| T_HA (bytes 3-5) |
+--------+--------+--------+--------+
| T_L32 (bytes 0-3) |
+--------+--------+--------+--------+
| T_NID (bytes 0-3) |
+--------+--------+--------+--------+
| T_NID (bytes 4-7) |
+--------+--------+--------+--------+
Figure 2.1: ILNPv4 ARP Request packet format
In the diagram of Fig 2.1, the fields are as follows:
HT Hardware Type (*)
PT Protocol Type (*)
HAL Hardware Address Length (*)
PAL Protocol Address Length (uses new value 12)
OP Operation Code (uses experimental value OP_EXP1=24)
S_HA Sender Hardware Address (*)
S_L32 Sender L32 (* same as Sender IPv4 address for ARP)
S_NID Sender Node Identifier (8 bytes)
T_HA Target Hardware Address (*)
T_L32 Target L32 (* same as Target IPv4 address for ARP)
T_NID Target Node 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 (OP code 2), except that the ILNPv4
ARP Request is sent only by nodes that support ILNPv4.
The field descriptions marked with "*" should have the same
values as for ARP as used for IPv4.
2.2 ILNPv4 ARP Reply Packet Format
The ILNPv4 ARP Reply is an extended version of the widely
deployed ARP Reply (OP code 2). For experimentation purposes,
the ILNPv4 ARP Request OP code uses decimal value 25. It is
important to note that decimal value 25 is a pre-defined,
shared-use experimental OP code for ARP [RFC5494], and is not
uniquely assigned to ILNPv4 ARP Requests. Th ILNPv4 ARP Reply
extension permits the Node's Identifier (NID) 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
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+--------+--------+--------+--------+
| 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_NID (bytes 0-1)|
+--------+--------+--------+--------+
| S_NID (bytes 2-5) |
+--------+--------+--------+--------+
|S_ID (bytes 6-7) | T_HA (bytes 0-1)|
+--------+--------+--------+--------+
| T_HA (bytes 3-5) |
+--------+--------+--------+--------+
| T_L32 (bytes 0-3) |
+--------+--------+--------+--------+
| T_NID (bytes 0-3) |
+--------+--------+--------+--------+
| T_NID (bytes 4-7) |
+--------+--------+--------+--------+
Figure 2.2: ILNPv4 ARP Reply packet format
In the diagram of Fig 2.2, the fields are as follows:
HT Hardware Type (*)
PT Protocol Type (*)
HAL Hardware Address Length (*)
PAL Protocol Address Length (uses new value 12)
OP Operation Code (uses experimental value OP_EXP2=25)
S_HA Sender Hardware Address (*)
S_L32 Sender L32 (* same as Sender IPv4 address for ARP)
S_NID Sender Node Identifier (8 bytes)
T_HA Target Hardware Address (*)
T_L32 Target L32 (* same as Target IPv4 address for ARP)
T_NID Target Node 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 (OP code 2), except that the ILNPv4 ARP
Reply is sent only by nodes that support ILNPv4.
The field descriptions marked with "*" should have the same
values as for ARP as used for IPv4.
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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 MUST use:
1. a 32-bit L32 value (_L32 suffixes in Figs 2.1 & 2.2)
2. a 64-bit NID value (_NID suffixes in Figs 2.1 & Fig 2.2)
b) where an IPv4 ARP Reply would use IPv4 addresses, an
ILNPv4 ARP Reply MUST use:
1. a 32-bit L32 value (_L32 suffixes in Figs 2.1 & 2.2)
2. a 64-bit NID value (_NID suffixes in Figs 2.1 & Fig 2.2)
As the OP codes 24 and 25 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 existing ARP
implementations rather than having to write an entirely new
implementation for ILNPv4. It should be emphasised, however, that
OP codes 24 and 25 are for experimental use as defined in [RFC5494],
and so it is possible that other experimental protocols could be
using these OP codes concurrently.
3. SECURITY CONSIDERATIONS
Security considerations for the overall ILNP Architecture are
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 (ND); 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. [RFC5227] both
describes several of these risks and also describes some measures
that an ARP implementation can use to reduce the chance of
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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.
In situations where additional protection against on-link
attackers is needed, for example within high-risk operational
environments, the IEEE standards for link-layer security
[IEEE-802.1-AE] SHOULD be implemented and deployed.
Implementers of this specification need to understand that the 2
OP code values used for these 2 extensions are not uniquely
assigned to ILNPv4. Other experimenters might be using the same
2 OP code values at the same time for different ARP-related
experiments. Absent prior coordination among all users of a
particular IP subnetwork, different experiments might be
occurring on the same IP subnetwork. So implementations of these
2 ARP extensions ought to be especially defensively coded.
4. IANA CONSIDERATIONS
This document makes no request of IANA.
If in future the IETF decided to standardise ILNPv4, then
allocation of unique ARP OP codes for the two extensions above
as part of the IETF standardisation process would be sensible.
5. REFERENCES
This document has both Normative and Informational References.
5.1 Normative References
[RFC826] D. Plummer, "An Ethernet Address Resolution Protocol",
RFC-826, Nov 1982.
[RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14, RFC-2119,
March 1997.
[RFC5227] S. Cheshire, "IPv4 Address Conflict Detection",
RFC-5227, July 2008.
[RFC5494] J. Arkko & C. Pignataro, "IANA Allocation Guidelines
for the Address Resolution Protocol", RFC-5494,
April 2009.
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[IEEE-802.1-AE] IEEE, "Media Access Control (MAC) Security",
IEEE Standard 802.1 AE, 18 August 2006, IEEE,
New York, NY, 10016, USA.
[ILNP-ARCH] R.J. Atkinson & S.N. Bhatti,
"ILNP Architectural Description",
draft-irtf-rrg-ilnp-arch, 10 July 2012.
[ILNP-DNS] R.J. Atkinson, S.N. Bhatti, & S Rose,
"DNS Resource Records for ILNP",
draft-irtf-rrg-ilnp-dns, 10 July 2012.
[ILNP-ENG] R.J. Atkinson & S.N. Bhatti,
"ILNP Engineering and Implementation Considerations",
draft-irtf-rrg-ilnp-eng, 10 July 2012.
[ILNP-ICMPv4] R.J. Atkinson & S.N. Bhatti,
"ICMPv4 Locator Update message"
draft-irtf-rrg-ilnp-icmpv4, 10 July 2012.
[ILNP-v4OPTS] R.J. Atkinson & S.N. Bhatti,
"IPv4 Options for ILNP",
draft-irtf-rrg-ilnp-v4opts, 10 July 2012.
5.2 Informative References
[ILNP-ICMPv6] R.J. Atkinson & S.N. Bhatti,
"ICMPv6 Locator Update message"
draft-irtf-rrg-ilnp-icmpv6, 10 July 2012.
[ILNP-NONCEv6] R.J. Atkinson & S.N. Bhatti,
"IPv6 Nonce Destination Option for ILNPv6",
draft-irtf-rrg-ilnp-noncev6, 10 July 2012.
[ILNP-ADV] R.J. Atkinson & S.N. Bhatti,
"Optional Advanced Deployment Scenarios for ILNP",
draft-irtf-rrg-ilnp-adv, 10 July 2012.
ACKNOWLEDGEMENTS
Steve Blake, Stephane Bortzmeyer, Mohamed Boucadair, Noel
Chiappa, Wes George, Steve Hailes, Joel Halpern, Mark Handley,
Volker Hilt, Paul Jakma, Dae-Young Kim, Tony Li, Yakov Rehkter,
Bruce Simpson, Robin Whittle and John Wroclawski (in alphabetical
order) provided review and feedback on earlier versions of this
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document. Steve Blake provided an especially thorough review of
an early version of the entire ILNP document set, which was
extremely helpful. We also wish to thank the anonymous reviewers
of the various ILNP papers for their feedback.
Roy Arends provided expert guidance on technical and procedural
aspects of DNS issues.
RFC EDITOR NOTE
This section is to be removed prior to publication.
Please note that this document is written in British English, so
British English spelling is used throughout. This is consistent
with existing practice in several other RFCs, for example
RFC-5887.
This document tries to be very careful with history, in the
interest of correctly crediting ideas to their earliest
identifiable author(s). So in several places the first published
RFC about a topic is cited rather than the most recent published
RFC about that topic.
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: 10 JAN 2013
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