NETEXT WG S. Gundavelli, Ed.
Internet-Draft Cisco
Intended status: Standards Track X. Zhou
Expires: February 23, 2012 ZTE Corporation
J. Korhonen
Nokia Siemens Networks
G. Feige
R. Koodli
Cisco
August 22, 2011
IPv4 Traffic Offload Selector Option for Proxy Mobile IPv6
draft-ietf-netext-pmipv6-sipto-option-00.txt
Abstract
This specification defines a mechanism and a related mobility option
for carrying IPv4 Offload traffic selectors between a mobile access
gateway and a local mobility anchor in a Proxy Mobile IPv6 domain.
Based on the received offload flow selectors from the local mobility
anchor, a mobile access gateway can enable offload traffic rule on
the selected IPv4 flows.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on February 23, 2012.
Copyright Notice
Copyright (c) 2011 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Terminology . . . . . . . . . . . . . . . . . . 3
2.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. LMA Considerations . . . . . . . . . . . . . . . . . . . . 5
3.2. MAG Considerations . . . . . . . . . . . . . . . . . . . . 6
4. IP Traffic Offload Selector Option . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
Mobile Operators are expanding their network coverage by integrating
various access technology domains into a common IP mobile core. For
providing IP mobility support to a mobile node irrespective of the
access network to which it is attached, the 3GPP S2/a Proxy Mobile
IPv6 [TS23402] interface, specified by the 3GPP system architecture,
is providing the needed protocol glue. When this protocol interface
based on Proxy Mobile IPv6 [RFC5213] is used, the mobile node is
topologically anchored on the local mobility anchor [RFC5213] in the
home network. The mobile node's IP traffic is always tunneled back
from the mobile access gateway [RFC5213] in the access network to the
local mobility anchor in the home network.
However, with the exponential growth in the mobile data traffic,
mobile operators are exploring new ways to offload some of the IP
traffic flows at the nearest access edge where ever there is an
internet peering point, as supposed to carrying it all the way to the
mobility anchor in the home network. Not all IP traffic needs to be
routed back to the home network, some of the non-essential traffic
which does not require IP mobility support can be offloaded at the
mobile access gateway in the access network. This approach provides
greater leverage and efficient usage of the mobile packet core with
increased overall network capacity and by lowering transport costs.
The local mobility anchor in the home network can potentially deliver
the IP flow selectors to the mobile access gateway in the access
network, for identifying the IP flows that needs to be offloaded.
This document defines a new mobility option, IP Traffic Offload
Selector option for Proxy Mobile IPv6 (PMIPv6). This option can be
used by the local mobility anchor for notifying the flow selectors
for that can be used by the local mobility anchor for notifying the
mobile access gateway flows that can be offloaded at the access edge.
Since, the mobile node's IP address topologically belongs to the home
network, the offloaded IP traffic flows need to be NAT [RFC2663]
translated. Given this NAT translation requirement for the offloaded
traffic, this approach will be limited to mobile node's IPv4 flows.
There are better ways to solve this problem for IPv6 and with the
goal not to create NAT66 requirement, this specification does not
support traffic offload support for IPv6 flows. This document also
does not define any new semantics for flow selectors. The flow
identification and the related semantics are all leveraged from
[RFC6088].
2. Conventions and Terminology
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2.1. 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 RFC 2119 [RFC2119].
2.2. Terminology
All the mobility related terms used in this document are to be
interpreted as defined in the base Proxy Mobile IPv6 specifications
[RFC5213] and [RFC5844]. Additionally, this document uses the
following abbreviations:
IP Flow
IP Flow represents a set of IP packets that match a traffic
selector. The selector is typically based on the source IP
address, destination IP address, source port, destination port and
other fields in upper layer headers.
Selective IP Traffic Offload (SIPTO)
Ability to select specific IP flows and route them to the local
network, as supposed to tunneling them to the home network.
NAT (Network Address Translation)
Network Address Translation [RFC2663] is a method by which IP
addresses are mapped from one address realm to another, providing
transparent routing to end hosts.
3. Solution Overview
The following illustrates the scenario where the mobile access
gateway in an access network having the ability to offload some of
the IPv4 traffic flows, based on the traffic selectors it received
from the local mobility anchor in the home network.
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_----_
_( )_
( Internet )
(_ _)
'----'
|
(IPv4 Traffic Offload Point
at access edge gateway for
non-essential traffic)
|
......................................................
| . +----------------+
+---+ . | Operator Value |
|NAT| . | Added Services |
+---+ . +----------------+
| _----_ |
+-----+ _( )_ +-----+
[MN]----| MAG |======( IP )======| LMA |-- Internet
+-----+ (_ _) +-----+
'----'
.
.
.
[Access Network] . [Home Network]
......................................................
Figure 1: Access Networks attached to MAG
3.1. LMA Considerations
The following considerations apply to the local mobility anchor and
the mobile access gateway.
Figure 1 explains the operational sequence of the IP Traffic Offload
selectors between the mobile access gateway and the local mobility
anchor.
MN MAG(NAT) LMA
|------>| | 1. Mobile Node Attach
| |------->| 2. Proxy Binding Update
| |<-------| 3. Proxy Binding Acknowledgement (IPTS Option)
| |========| 4. Tunnel/Route Setup
| + | 5. Installing the traffic offload rules
|------>| | 6. IPv4 packet from mobile node
| | | 7. Forwarding rule - Tunnel home/offload
| | |
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Figure 2: Exchange of IP Traffic Offload Selectors
o If the received Proxy Binding Update includes the IP Traffic
Offload Selector Option Section 4, but if the local mobility
anchor either does not have the SIPTO capability, or it chooses to
deny the SIPTO request, the local mobility anchor MUST ignore the
IP Traffic Offload Selector Option and this would have no effect
on the operation of the rest of the protocol.
o If the local mobility anchor has the SIPTO capability and chooses
to deliver the flow policies, the local mobility anchor can
construct the traffic selectors based on the routing policy and
deliver those selectors in the Proxy Binding Acknowledgement
message using the IP Traffic Offload Selector Option. If the
received Proxy Binding Update included a proposed Offload traffic
selectors, the local mobility anchor MAY choose to honor that
request.
3.2. MAG Considerations
o The mobile access gateway MAY choose to notify the local mobility
anchor about its SIPTO capability by including the IP Traffic
Offload Selector Option Section 4 in the Proxy Binding Update
message. The included option MAY include the proposed offload
selectors which the local mobility anchor may choose to override.
If the mobile access gateway cannot does not have SIPTO
capability, this option MUST NOT be included in the Proxy Binding
Update.
o If there is no IP Traffic Offload Selector Option in the
corresponding Proxy Binding Acknowledgement message, it is
considered that the local mobility anchor does not support SIPTO
capability, specifically, it cannot deliver selectors for IP
traffic offload flows.
o If there IP Traffic Offload Selector Option in the corresponding
Proxy Binding Acknowledgement message, it serves as an hint that
the local mobility anchor can support SIPTO and the included
traffic spec MUST be applied by the mobile access gateway.
4. IP Traffic Offload Selector Option
A new option, IP Traffic Offload Selector option, is defined for
using it in Proxy Binding Update (PBU) and Proxy Binding
Acknowledgement (PBA) messages exchanged between a local mobility
anchor and a mobile access gateway. This option is used for carrying
the flow selectors for supporting IP traffic offload function at the
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mobile access gateway. The option includes the parameters for
selecting IPv4 flows for offload.
The alignment requirement for this option is 4n.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|O| Reserved | TS Format |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic Selector ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: IP Traffic Offload Selector Option
Type
<IANA>
Length
8-bit unsigned integer indicating the length in octets of the
option, excluding the type and length fields.
Reserved This field is unused for now. The value MUST be
initialized to 0 by the sender and MUST be ignored by the
receiver.
TS Format An 8-bit unsigned integer indicating the Traffic Selector
Format. Value "0" is reserved and MUST NOT be used. The value of
(1) is assigned for IPv4 Binary Traffic Selector [RFC6088].
TS Selector A variable-length opaque field for including the traffic
specification identified by the TS format field. When the value
of TS Format field is set to (1), the format that follows is the
IPv4 Binary Traffic Selector specified in section 3.1 of
[RFC6088].
5. IANA Considerations
This document requires the following two IANA actions.
o Action-1: This specification defines a new Mobility Header option,
IP Traffic Offload Selector option. This option is described in
Section 4. The Type value for this option needs to be assigned
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from the same numbering space as allocated for the other mobility
options [RFC6275].
o Action-2: The Sub-type field of the IP Traffic Offload Selector
option introduces a new number space. This number space needs to
be managed by IANA, under the Registry, IP Traffic Offload
Selector Type Registry. This specification reserves the sub-type
value of (1) and (2). Approval of new sub-type values are to be
made through IANA Expert Review.
6. Security Considerations
The IP Traffic Offload Selector option defined in this specification
is for use in Proxy Binding Update and Proxy Binding Acknowledgement
messages. This option is carried like any other mobility header
option as specified in [RFC5213] and does not require any special
security considerations. Carrying IP traffic offload selectors does
not introduce any new security vulnerabilities.
7. Acknowledgements
The authors would like to thank Rajesh Pazhyannur, Kent Leung, Mark
Grayson, Frank Brockners, Woj Dec, and Steve Wood for all the
discussions related to the topic of IP traffic offload. The authors
would like to acknowledge the work related SIPTO in 3GPP SA2 working
group.
8. References
8.1. 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.
[RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", RFC 5844, May 2010.
[RFC6088] Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont,
"Traffic Selectors for Flow Bindings", RFC 6088,
January 2011.
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8.2. Informative References
[RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address
Translator (NAT) Terminology and Considerations",
RFC 2663, August 1999.
[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011.
[TS23402] 3GPP, "Architecture enhancements for non-3GPP accesses",
2010.
Authors' Addresses
Sri Gundavelli (editor)
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
Email: sgundave@cisco.com
Xingyue Zhou
ZTE Corporation
No.68 Zijinghua Rd
Nanjing
China
Email: zhou.xingyue@zte.com.cn
Jouni Korhonen
Nokia Siemens Networks
Linnoitustie 6
Espoo FIN-02600
Finland
Email: jouni.nospam@gmail.com
Gaetan
Cisco
France
Email: gfeige@cisco.com
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Rajeev Koodli
Cisco
3650 Cisco Way
San Jose, CA 95134
USA
Email: rkoodli@cisco.com
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