Network Working Group G. Tsirtsis
Internet-Draft V. Park
Intended status: Standards Track V. Narayanan
Expires: May 12, 2010 Qualcomm
K. Leung
Cisco
November 8, 2009
Dynamic Prefix Allocation for NEMOv4
draft-ietf-mip4-nemov4-dynamic-03.txt
Abstract
The base NEMOv4 specification defines extensions to Mobile IPv4 for
mobile networks. This specification defines a dynamic prefix
allocation mechanism.
Status of this Memo
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Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Dynamic Mobile Prefix allocation . . . . . . . . . . . . . . . 5
3.1. Mobile Client Considerations . . . . . . . . . . . . . . . 5
3.2. Home Agent Considerations . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Normative References . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
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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].
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2. Introduction
The base NEMOv4 specification [RFC5177] defines extensions to Mobile
IPv4 [RFC3344] for mobile networks. This specification adds support
for dynamic allocation of mobile prefixes by the home agent.
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3. Dynamic Mobile Prefix allocation
The following extension is defined according to this specification.
3.1. Mobile Client Considerations
[RFC5177] defines that the prefix field of the mobile network request
extension can not be set to zero. This mechanism works only in
combination with the explicit mode of operation defined in [RFC5177].
According to this specification, a mobile client MAY include one or
more mobile network request extensions with the prefix field set to
zero. Such mobile network request extensions indicate that the
mobile client requests mobile network prefix(es) to be assigned to it
by the home agent. In this case, the mobile client MAY set the
prefix length field of such extensions to zero or to a length of its
choice as a hint to the home agent. According to this specification,
mobile network request extensions with the prefix field set to zero
MAY be included in a registration request message either during
initial registration or during a subsequent registration.
When a mobile client receives a registration reply it MUST process it
as defined in MIPv4 [RFC3344] and [RFC5177]. If one or more network
acknowledgement extension are included with the Code field set to
"Success" the mobile client SHOULD treat the prefixes in the
corresponding prefix fields as allocated prefixes and create the
appropriate bindings as defined in [RFC5177].
If in response to a registration request with a mobile network
request extension with the prefix field set to zero, a mobile client
receives a registration reply with a network acknowledgement
extensiona including Code field set to 1 "invalid prefix", it may use
it as a hint that the home agent does not support dynamic prefix
allocation.
3.2. Home Agent Considerations
A home agent receiving a mobile network request extension with the
prefix field set to zero MAY return a mobile network acknowledgement
extension [RFC5177] with the prefix field set to the prefix allocated
to the mobile client. The length of that prefix is at the discretion
of the home agent. The home agent MAY take into account the prefix
length hint if one is included in the mobile network request
extension. Once the home agent allocates a prefix it MUST maintain
the prefix registration table as defined in [RFC5177]. Alternatively
the home agent MAY return a mobile network acknowledgement extension
with the Code field set to one of the negative codes defined in
[RFC5177].
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Dynamic mobile prefix allocation as defined in this specification MAY
be combined with dynamic home address allocation as defined in
[RFC5177]. In other words the home address field of the registration
request message MAY be set to zero while the message also includes
one or more mobile network request extensions with the prefix field
also set to zero.
Once the home agent allocates a prefix it MUST maintain the prefix
registration table as defined in [RFC5177]. The lifetime of the
allocated prefix will be equal to the lifetime of the binding cache
entry
For dynamic prefix allocation the mobile client's home address MAY be
used to identify the client if it is not set to zero. Otherwise, as
defined in the NAI extension [RFC2794] of MIPv4 [RFC2794], the NAI
extension needs to be included in the registration request, in which
case the same extension SHOULD be used to identify the mobile client
for prefix allocation purposes.
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4. Security Considerations
This specification operates in the security constraints and
requirements of MIPv4 [RFC3344], NAI [RFC2794] and [RFC5177].
Home agent implementations SHOULD take steps to prevent address
exhaustion attacks. One way to limit the effectiveness of such an
attack is to limit the number and size of prefixes any one mobile
router can be allocated.
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5. IANA Considerations
This document has no actions for IANA
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6. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2794] Calhoun, P. and C. Perkins, "Mobile IP Network Access
Identifier Extension for IPv4", RFC 2794, March 2000.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
[RFC5177] Leung, K., Dommety, G., Narayanan, V., and A. Petrescu,
"Network Mobility (NEMO) Extensions for Mobile IPv4",
RFC 5177, April 2008.
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Authors' Addresses
George Tsirtsis
Qualcomm
Email: tsirtsis@googlemail.com
Vincent Park
Qualcomm
Phone: +908-947-7084
Email: vpark@qualcomm.com
Vidya Narayana
Qualcomm
Phone: +858-845-2483
Email: vidyan@qualcomm.com
Kent Leung
Cisco
Phone: +408-526-5030
Email: kleung@cisco.com
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