Internet DRAFT - draft-feng-dmm-ra-prefixtype
draft-feng-dmm-ra-prefixtype
DMM Working Group W. Feng
Internet-Draft PSU
Intended status: Standards Track D. Moses
Expires: March 16, 2019 Intel
September 12, 2018
Router Advertisement Prefix Option Extension for On-Demand Mobility
draft-feng-dmm-ra-prefixtype-03
Abstract
Router Advertisement / Router Solicitation is one of the ways for
hosts to establish network IPv6 connectivity configuration. This
document describes two approches to allowing a router to specify
mobility service type availability to mobile hosts. Mobile hosts can
then configure their IP address to the preferred type of mobile
connectivity. Two possibilities are considered: (i) creating an
extension to the router advertisement prefix information option to
allow the router to specify mobility connectivity types, and (ii)
specifying a new RA options that allows the router to specify the
mobility connectivity types.
Status of This Memo
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This Internet-Draft will expire on March 16, 2019.
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Copyright (c) 2018 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
Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 2
3. Router Advertisement Extensions . . . . . . . . . . . . . . . 3
3.1. Modifying PIO . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Adding a new RA option . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Normative References . . . . . . . . . . . . . . . . . . 7
6.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
[I-D.ietf-dmm-ondemand-mobility] defines different types of mobility
related network services provided by access network to mobile hosts.
In particular, it defines different types of prefix continuity types
as mobile nodes move between different points of attachments.
This document proposes two such options to the router advertisement
message ([RFC4861]) to allow the router to convey mobility services
associated with an Ipv6 prefix. The possibilities considered are:
(i) creating an extension to the router advertisement prefix
information option to allow the router to specify mobility
connectivity types, and (ii) specifying a new RA options that allows
the router to specify the mobility connectivity types.
For (i), the prefix information option is extended to support the
specification of mobility type. In (ii), a new RA option field is
provided to do the same.
2. Notational Conventions
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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3. Router Advertisement Extensions
IP prefixes are conveyed in Router Advertisement messages through the
Prefix Information Option field ([RFC4861]). These prefix
information option fields are used to allow hosts to configure their
IPv6 addresses.
For distributed mobility management, there is a need for a network to
be able to convey different prefixes for different connectivity
scenarios. [I-D.ietf-dmm-ondemand-mobility] defines different
service continuity requirements including: Non-Persistent, Session-
Lasting, Fixed, and Graceful-replacement. Currently, however, there
is no way for a router to specify the continuity type through a
router advertisement message.
This document proposes two possibilities for modifying the router
advertisement message to include mobility service options that it is
offering to mobile hosts that are attached: (i) creating an extension
to the router advertisement prefix information option (PIO) to allow
the router to specify mobility connectivity types, and (ii)
specifying a new RA options that allows the router to specify the
mobility connectivity types.
3.1. Modifying PIO
The first option is to modify the PIO. The advantages of this
approach are that it is semantically in line with the intended
function. That is, specifying prefix options. This, however,
requires the modification of several bits in the existing PIO to
support the specification of the type.
The modified prefix information option fields are shown in the
following figure:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Prefix Length |L|A| Rsv1|SrvTp|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Valid Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preferred Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Prefix +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fields:
Type 3
Length 4
Prefix Length 8-bit unsigned integer. The number of leading bits in
the Prefix that are valid. The value ranges from 0 to
128.
L 1-bit on-link flag. When set, indicates that this
prefix can be used for on-link determination.
A 1-bit autonomous address-configuration flag. When set
indicates that this prefix can be used for stateless
address configuration.
Rsv1 3-bit unused field. It MUST be initialized to zero by
the sender and MUST be ignored by the receiver.
SrvTp 3-bit field that specifies the service type. The
field can have the following values:
Non-Persistent - a non-persistent IP prefix (1)
Session-Lasting - a session-lasting IP prefix (2)
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Fixed - a fixed IP prefix (3)
Graceful-replacement - a graceful-replacement IP
prefix (4)
The definition of these service types is available in
[I-D.ietf-dmm-ondemand-mobility].
0 is reserved and should not be used. All other values (5-7) are
reserved for future use.
The value of the Service Type indicates the type of continuity
service committed by the network for the associated IPv6 prefix.
Once an IPv6 prefix type is provided, any subsequent messages
involving this prefix (lease renewal - for example) must include the
IPv6 Continuity Service option with the same service type that was
assigned by the server during the initial allocation.
Given the list of IPv6 prefixes and their associated mobility service
type, the mobile host can then configure its IP address to the
appropriate service required by the application
Mobile hosts that do not support this new option should ignore the
prefix information option.
Routers should also send an additional prefix information option
without the session-type field from time to time for hosts that do
not support this new format.
3.2. Adding a new RA option
The second approach is to add a new RA option alongside the existing
PIO (and other RA options). The advantage of this approach are that
it leaves the existing PIO untouched. Furthermore, hosts that
receive this option with the type that they do not understand can
simply disregard it.
The new RA option specification is shown in the following figure:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Prefix Length |L|A| Rsv1|SrvTp|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Valid Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preferred Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Prefix +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fields:
Type Need to define new Type #
Length 4
Prefix Length 8-bit unsigned integer. The number of leading bits in
the Prefix that are valid. The value ranges from 0 to
128.
L 1-bit on-link flag. When set, indicates that this
prefix can be used for on-link determination.
A 1-bit autonomous address-configuration flag. When set
indicates that this prefix can be used for stateless
address configuration.
Rsv1 3-bit unused field. It MUST be initialized to zero by
the sender and MUST be ignored by the receiver.
SrvTp 3-bit field that specifies the service type. The
field can have the following values:
Non-Persistent - a non-persistent IP prefix (1)
Session-Lasting - a session-lasting IP prefix (2)
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Fixed - a fixed IP prefix (3)
Graceful-replacement - a graceful-replacement IP
prefix (4)
The definition of these service types is available in
[I-D.ietf-dmm-ondemand-mobility].
0 is reserved and should not be used. All other values (5-7) are
reserved for future use.
The value of the Service Type indicates the type of continuity
service committed by the network for the associated IPv6 prefix.
Once an IPv6 prefix type is provided, any subsequent messages
involving this prefix (lease renewal - for example) must include the
IPv6 Continuity Service option with the same service type that was
assigned by the server during the initial allocation.
Given the list of IPv6 prefixes and their associated mobility service
type, the mobile host can then configure its IP address to the
appropriate service required by the application
Mobile hosts that do not support this new option should ignore the
prefix information option.
Routers should also send an additional prefix information option
without the session-type field from time to time for hosts that do
not support this new format.
4. Security Considerations
There are no specific security considerations for this option.
5. IANA Considerations
TBD
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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6.2. Informative References
[I-D.ietf-dmm-distributed-mobility-anchoring]
Chan, A., Wei, X., Lee, J., Jeon, S., and C. Bernardos,
"Distributed Mobility Anchoring", draft-ietf-dmm-
distributed-mobility-anchoring-11 (work in progress),
August 2018.
[I-D.ietf-dmm-ondemand-mobility]
Yegin, A., Moses, D., Kweon, K., Lee, J., Park, J., and S.
Jeon, "On Demand Mobility Management", draft-ietf-dmm-
ondemand-mobility-15 (work in progress), July 2018.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <https://www.rfc-editor.org/info/rfc3315>.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
DOI 10.17487/RFC3633, December 2003,
<https://www.rfc-editor.org/info/rfc3633>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC7934] Colitti, L., Cerf, V., Cheshire, S., and D. Schinazi,
"Host Address Availability Recommendations", BCP 204,
RFC 7934, DOI 10.17487/RFC7934, July 2016,
<https://www.rfc-editor.org/info/rfc7934>.
Authors' Addresses
Wu-chi Feng
Portland State Univ.
Hillsboro
USA
Email: wuchi@pdx.edu
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Danny Moses
Intel
Petah Tikva
Israel
Email: danny.moses@intel.com
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