Network Working Group F. Xia
Internet-Draft B. Sarikaya
Expires: January 1, 2010 Huawei USA
June 30, 2009
Differentiated Services Support for Proxy Mobile IPv6
draft-xia-netext-qos-00.txt
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Abstract
This document describes Quality of Service (QoS) provisioning in a
Proxy Mobile IPv6 domain through enabling differentiated services.
When a packet is encapsulated in a mobile access gateway (or a local
mobility anchor), the differentiated services codepoint (DSCP) field
in the outer header is mapped to the priority of a mobile node, or
the precedence of an application of the mobile node. Intermediary
routers between the mobile access gateway and the local mobility
anchor, which forward the packet based on the outer header of the
packet, prioritize the packet according to the DSCP value of the
outer header.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. IPv4 TOS/IPv6 Traffic Class Overview . . . . . . . . . . . . . 4
4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Priority Download from AAA . . . . . . . . . . . . . . . . 5
4.2. PHP Mapping . . . . . . . . . . . . . . . . . . . . . . . . 5
4.3. Encapsulation and Forwarding . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
Proxy Mobile IPv6 protocol [RFC5213] specifies network-based IP
mobility management support to a mobile node, without requiring the
participation of the mobile node in any IP mobility related
signaling. The core functional entities for proxy mobile IPv6 are
the Local Mobility Anchor (LMA) and the Mobile Access Gateway (MAG).
After signalling exchanges between the LMA and the MAG, a bi-
directional tunnel is established.
The local mobility anchor, being the topological anchor point for the
mobile node's home network prefix(es), receives any packets that are
sent to the mobile node by any node in or outside the Proxy Mobile
IPv6 domain. The local mobility anchor forwards these received
packets to the mobile access gateway through the bi-directional
tunnel. The mobile access gateway on other end of the tunnel, after
receiving the packet, removes the outer header and forwards the
packet on the access link to the mobile node.
The mobile access gateway acts as the default router on the point-to-
point link shared with the mobile node. Any packet that the mobile
node sends to any correspondent node will be received by the mobile
access gateway and will be sent to its local mobility anchor through
the bi-directional tunnel. The local mobility anchor on the other
end of the tunnel, after receiving the packet, removes the outer
header and routes the packet to the destination.
The following is the supported packet encapsulation modes that can be
used by the mobile access gateway and the local mobility anchor for
tunneling mobile node's IPv6 datagrams and for supporting IPv4
transport.
o IPv6-In-IPv6 - IPv6 datagram encapsulated in an IPv6 packet
o IPv6-In-IPv4 - IPv6 datagram encapsulation in an IPv4 packet
o IPv6-In-IPv4-UDP - IPv6 datagram encapsulation in an IPv4 UDP
packet
o IPv6-In-IPv4-UDP-TLV - IPv6 datagram encapsulation in an IPv4 UDP
packet with a TLV header.
[RFC5213] and its companion document
[I-D.ietf-netlmm-pmip6-ipv4-support] details the above
encapsulations. IPv6-In-IPv6 is taken as an instance in this
document, IPv4 encapsulation is also applicable.
[RFC5213] only describes how the ECN (Explicit Congestion
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Notification) part of IPv6 Traffic Class field being handled at the
tunnel entry and exit points, and there is no special consideration
on DSCP part of the field. This document describes Quality of
Service (QoS) provisioning in a Proxy Mobile IPv6 domain through
enabling differentiated services. When a packet is encapsulated in a
mobile access gateway (or a local mobility anchor), the DSCP
(differentiated services codepoint) field in the outer header is
mapped to the priority of a mobile node, or the precedence of an
application of the mobile node. Intermediary routers between the
mobile access gateway and the local mobility anchor, which forward
traffic based on outer headers of the packets, prioritize the packets
according to the DSCP values of the outer headers.
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 [RFC2119]. The
terminology in this document is based on the definitions in [RFC5213]
3. IPv4 TOS/IPv6 Traffic Class Overview
Traffic Class field in the IPv6 header [RFC2460] and Type of Service
field in the IPv4 header [RFC0791] serve the same function which is
available for use by originating nodes and/or forwarding routers to
identify and distinguish between different classes or priorities of
IPv6/IPv4 packets. [RFC2474] and [RFC3168] further detail Traffic
Class/ Type of Service field by defining DSCP and ECN field as
following.
0 1 2 3 4 5 6 7
+-----+-----+-----+-----+-----+-----+-----+-----+
| DS FIELD, DSCP | ECN FIELD |
+-----+-----+-----+-----+-----+-----+-----+-----+
DSCP: differentiated services codepoint
ECN: Explicit Congestion Notification
Regarding how to make use of DSCP field, [RFC2475] defines an
architecture for implementing scalable service differentiation in the
Internet. At the same time, [RFC2597] specifies a general use
differentiated services Per-Hop-Behavior (PHB) Group called Assured
Forwarding (AF), while [RFC2598] describes a PHB called Expedited
Forwarding.
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[RFC5213] only describes how the ECN information being handled at the
tunnel entry and exit points, and there is no special consideration
on DSCP.
4. Operations
4.1. Priority Download from AAA
The priority of subscribers MAY be stored in the mobile node's policy
profile which is downloaded from an AAA server to the mobile access
gateway once the mobile node attaches to a Proxy Mobile IPv6 Domain
and performs access authentication. During the binding update
exchange between the mobile access gateway and the local mobility
anchor, the local mobility anchor MAY interact with the AAA server in
order to access the mobile node's profile and update the remote
policy store with the mobility session related information.
4.2. PHP Mapping
To differientiate subscribers' packets forwarded between the mobile
access gateway and the local mobility anchor, the priority of
subscribers MUST be mapped to standard Per-Hop-Behavior. Different
operators MAY have different mapping, and the following is just as an
example.
+--------------+-----------------------+
| Priority | PHP |
|--------------|-----------------------|
| Platinum | EF |
| Golden | AF4 |
| Silver | AF1 |
| Other | BE |
+--------------+-----------------------+
Further, packets MAY even be differentiated by application types, for
example, VoIP service of Golden subscribers takes priority of web
surfing service of Platinum subscribers.
4.3. Encapsulation and Forwarding
On receiving a packet from a correspondent node with the destination
address matching a mobile node's home network prefix(es), the local
mobility anchor then
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o decides the priority based on the mobile node's profile and/or
application type,
o maps the priority to a pre-defined Per-Hop-Behavior,
o and fills the DSCP field of outer IP header when forwarding the
packet through the bi-directional tunnel. Intermediary routers
between the mobile access gateway and the local mobility anchor,
which forward traffic based on the outer header of the packet,
prioritize the packet according to the DSCP value of the outer
header.
A similar processing as above applies when the mobile access gateway
forwards upstream packets of the mobile node.
5. Security Considerations
Security consideration of [RFC5213] applies, and this document does
not introduce extra security threats.
6. Acknowledgements
TBD.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
December 1998.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP",
RFC 3168, September 2001.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
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September 1981.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, December 1998.
[RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski,
"Assured Forwarding PHB Group", RFC 2597, June 1999.
[RFC2598] Jacobson, V., Nichols, K., and K. Poduri, "An Expedited
Forwarding PHB", RFC 2598, June 1999.
7.2. Informative References
[I-D.ietf-netlmm-pmip6-ipv4-support]
Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", draft-ietf-netlmm-pmip6-ipv4-support-12
(work in progress), April 2009.
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Authors' Addresses
Frank Xia
Huawei USA
1700 Alma Dr. Suite 500
Plano, TX 75075
Phone: +1 972-509-5599
Email: xiayangsong@huawei.com
Behcet Sarikaya
Huawei USA
1700 Alma Dr. Suite 500
Plano, TX 75075
Phone: +1 972-509-5599
Email: sarikaya@ieee.org
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