NETEXT WG S. Gundavelli, Ed.
Internet-Draft Cisco
Intended status: Standards Track X. Zhou
Expires: August 3, 2012 ZTE Corporation
J. Korhonen
Nokia Siemens Networks
G. Feige
R. Koodli
Cisco
January 31, 2012
IPv4 Traffic Offload Selector Option for Proxy Mobile IPv6
draft-ietf-netext-pmipv6-sipto-option-02.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
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 3, 2012.
Copyright Notice
Copyright (c) 2012 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
Gundavelli, et al. Expires August 3, 2012 [Page 1]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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 . . . . . . . . . . . . . . . . . . . . 6
3.2. MAG Considerations . . . . . . . . . . . . . . . . . . . . 6
4. IP Traffic Offload Selector Option . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Protocol Configuration Variables . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
Gundavelli, et al. Expires August 3, 2012 [Page 2]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
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 S2a 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 at 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 which
help lowering transport cost. 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 to notify the mobile access gateway
with the flow selectors that can used for selecting the flows for
offloading them 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
Gundavelli, et al. Expires August 3, 2012 [Page 3]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
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)
The approach of selecting specific IP flows and routing 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. For example, all
the HTTP flows may be be offloaded at the mobile access gateway and
all the other flows for that mobility session are tunneled back to
the local mobility anchor.
The selectors that are delivered to the mobile access gateway can be
used to classify the traffic, so it can be offloaded to the local
access network. The parameters in the IP traffic selectors can be
used to match against the fields in the IP packet header. These
parameters include Source IP address, Destination IP address, TCP/UDP
Gundavelli, et al. Expires August 3, 2012 [Page 4]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
Port numbers, and other fields.
_----_
_( )_
( Internet )
(_ _)
'----'
|
(IPv4 Traffic Offload Point
at access edge gateway for
non-essential traffic
Ex: HTTP Traffic Offloaded)
|
......................................................
| . +----------------+
+---+ . | Operator Value |
|NAT| . | Added Services |
+---+ . +----------------+
| _----_ |
+-----+ _( )_ +-----+
[MN]----| MAG |======( IP )======| LMA |-- Internet
+-----+ (_ _) +-----+
'----' (
.
.
.
[Access Network] . [Home Network]
......................................................
Figure 1: Access Networks attached to MAG
Figure 1 explains the operational sequence of the Proxy Mobile IPv6
protocol signaling message exchange between the mobile access gateway
and the local mobility anchor for negotiating the IP Traffic Offload
selectors.
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
| | |
Gundavelli, et al. Expires August 3, 2012 [Page 5]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
Figure 2: Exchange of IP Traffic Offload Selectors
3.1. LMA Considerations
The following considerations apply to the local mobility anchor.
o If the received Proxy Binding Update includes the IP Traffic
Offload Selector Option Section 4, but if the configuration
variable, EnableIPTrafficOffloadSupport on the local mobility
anchor is set to a value of (0), then the local mobility anchor
MUST ignore the IP Traffic Offload Selector Option and process the
rest of the packet. This would not have no effect on the
operation of the rest of the protocol.
o If the received Proxy Binding Update includes the IP Traffic
Offload Selector Option Section 4, and if the configuration
variable, EnableIPTrafficOffloadSupport on the local mobility
anchor is set to a value of (1), then the local mobility anchor
can acquire the offload policy from a network function (Ex: AAA or
PCRF) and can construct the traffic selectors based on the offload
policy and deliver those selectors in the Proxy Binding
Acknowledgement message using the IP Traffic Offload Selector
Option. However, if the received Proxy Binding Update included a
proposed Offload traffic selectors, the local mobility anchor MAY
choose to honor that request and include the proposed selectors in
the reply.
3.2. MAG Considerations
o If the configuration variable, EnableIPTrafficOffloadSupport on
the mobile access gateway is set to a value of (0), then the
mobile access gateway MUST NOT include the IP Traffic Offload
Selector Option Section 4 in the Proxy Binding Update message that
it sends to the local mobility anchor. Otherwise, the option MUST
be included in the Proxy Binding Update message. When this option
is included, it is an indication to the local mobility anchor that
the mobile access gateway is capable of supporting IP Traffic
Offload support. The TS format field of the IP Traffic Offload
Selector Option MUST be set to a value of (0), indicating that the
mobile access gateway is not proposing any specific offload policy
for that mobility session, but a request to the local mobility
anchor to provide the IP traffic offload flow selectors for that
mobility session.
o The mobility access gateway MAY choose to include its proposed IP
traffic offload flow selectors in the IP Traffic Offload Selector
Option Section 4. Including this offload traffic selectors serves
as a proposal to the local mobility anchor, which the local
Gundavelli, et al. Expires August 3, 2012 [Page 6]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
mobility anchor can override with its own offload policy, or agree
to the proposed policy. When including the offload traffic
selectors, the TS format field of the IP Traffic Offload Selector
Option MUST be set to the respective flow specification type.
o If there is no IP Traffic Offload Selector Option in the
corresponding Proxy Binding Acknowledgement message, that the
mobile access gateway receives in response to a Proxy Binding
Update, it serves as an indication that the local mobility anchor
does not support IP Traffic Offload support for that mobility
session, and it implies the local mobility anchor cannot deliver
IP flow selectors for that mobility session. The mobile access
gateway upon accepting the Proxy Binding Acknowledgement message
MUST NOT enable any offload policy for that mobility session. All
the mobile node's IP flows MUST be tunneled back to the local
mobility anchor.
o If there is IP Traffic Offload Selector Option in the
corresponding Proxy Binding Acknowledgement message, it is an
indication that the local mobility anchor has provided the IP
traffic Offload selectors for that mobility session [RFC5213] and
the identified IP flows have to be offloaded. Considerations
related to (M) flag MUST be applied.
4. IP Traffic Offload Selector Option
A new mobility 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 mobile access
gateway and a local mobility anchor. This option is used for
carrying the flow selectors for enabling IP traffic offload function
at the mobile access gateway.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M| Reserved | TS Format |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic Selector ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Gundavelli, et al. Expires August 3, 2012 [Page 7]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
Figure 3: IP Traffic Offload Selector Option
Type
<IANA-1>
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.
IP Traffic Offload Mode Flag
This field indicates the offload mode. If the (M) flag value is
set to a value of (1), it is an indication that all the flows
except the identified IP flow(s) in this mobility option needs to
be offloaded at the mobile access gateway. If the (M) flag value
is set to a value of (0), it is an indication that the identified
IP flow(s) needs to be offloaded at the mobile access gateway and
all other IP flows associated with that mobility session needs to
be tunneled to the local mobility anchor.
TS Format
An 8-bit unsigned integer indicating the Traffic Selector Format.
The value of "0" is reserved and is used when there are no
selectors to carry, relevant when the option is used as a
capability indicator. The value of (1) is assigned for IPv4
Binary Traffic Selector [RFC6088]. All other values are reserved
by IANA for future allocations.
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
from the same numbering space as allocated for the other mobility
options [RFC6275].
Gundavelli, et al. Expires August 3, 2012 [Page 8]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
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
values of (0) and (1). The value of "0" is reserved and is used
when there are no selectors to carry, relevant when the option is
used just as a capability indicator. The value of (1) is assigned
for IPv4 Binary Traffic Selector [RFC6088]. Approval of new sub-
type values are to be made through IANA Expert Review.
6. Protocol Configuration Variables
This specification defines the following configuration variable that
control the use of IP Traffic Offload support for a mobility session.
The mobility entities, local mobility anchor and the mobile access
gateway MUST allow these variables to be configured by the system
management. The configured values for these protocol variables MUST
survive server reboots and service restarts.
EnableIPTrafficOffloadSupport
This flag indicates whether or not IP Traffic Offload support
needs to be enabled. This configuration variable is available
at both in the mobile access gateway and at the local mobility
anchor. The default value for this flag is set to (0),
indicating that the support for IP Traffic offload support is
disabled.
When this flag on the mobile access gateway is set to a value
of (1), the mobile access gateway MUST enable the IP Traffic
offload support for a mobility session, specifically it MUST
include the IP Traffic Offload Selector option in the Proxy
Binding Update messages and offload the negotiated IP flows to
the access network. If the value of the flag is set to a value
of (0), mobile access gateway MUST NOT enable IP Traffic
Offload support and it MUST NOT include this option in the
Proxy Binding Update.
Similarly, when this flag on the local mobility anchor is set
to a value of (1), the local mobility anchor SHOULD enable
support for IP Traffic offload support. When the local
mobility anchor chooses to enable IP Traffic offload support
and if there is offload flow policy specified for a mobility
node, it SHOULD deliver the offload selectors to the mobile
access gateway by including the IP Traffic Offload Selector
option in the Proxy Binding Acknowledgement message.
Gundavelli, et al. Expires August 3, 2012 [Page 9]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
7. 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.
When IPv4 traffic offload support is enabled for a mobile node, the
mobile access gateway selectively offloads some of the mobile node's
traffic flows to the local access network. Typically, these
offloaded flows get NAT translated and essentially that introduces
certain vulnerabilities which are common to any NAT deployment.
These vulnerabilities and the related considerations have been well
documented in the NAT specification [RFC2663]. There are no
additional considerations above and beyond what is already documented
by the NAT specifications and which are unique to the approach
specified in this document.
8. Acknowledgements
The authors would like to thank Ahmad Muhanna, Basavaraj Patil,
Carlos Bernardos, Eric Voit, Frank Brockners, Hidetoshi Yokota, Mark
Grayson, Pierrick Seite, Ryuji Wakikawa, and Steve Wood for all the
discussions related to the topic of IP traffic offload.
9. References
9.1. 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.
Gundavelli, et al. Expires August 3, 2012 [Page 10]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
9.2. 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
Gundavelli, et al. Expires August 3, 2012 [Page 11]
Internet-Draft IPv4 Traffic Offload Selector Option January 2012
Rajeev Koodli
Cisco
3650 Cisco Way
San Jose, CA 95134
USA
Email: rkoodli@cisco.com
Gundavelli, et al. Expires August 3, 2012 [Page 12]
