Network Working Group B. Patil Internet-Draft Nokia Intended status: Standards Track K. Chowdhury Expires: September 9, 2009 Starent Networks D. Premec Nokia Siemens Networks March 8, 2009 DHCP options for Access Point Name and attach type indication draft-patil-dhc-apn-attachtype-options-01.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 9, 2009. Copyright Notice 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 Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Patil, et al. Expires September 9, 2009 [Page 1] Internet-Draft APN and ATTACH_Type Options March 2009 Abstract Access Point Names are used in wireless networks which are based on 3GPP standards to identify a specific gateway element. A mobile node which attaches via a 3GPP access network indicates the gateway to which connectivity is desired by providing the gateways access point name, in the network attach signaling messages. This document specifies a new DHCP option which enables the mobile node to request connectivity to a gateway, identified by the access point name, in DHCP messages. A mobile node whose mobility is managed by the network using Proxy Mobile IPv6 protocol may perform a handover from one access technology to another. This document defines a DHCP option which enables the host to indicate to Proxy Mobile IPv6 elements in the access network if the attachment via the new interface is a handover or a new connection. Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. DHCP options for APN and Attach-type . . . . . . . . . . . . . 6 4.1. DHCPv6 Attach Information option . . . . . . . . . . . . . 6 4.2. DHCPv4 Attach Information option . . . . . . . . . . . . . 7 4.3. Attach Info Data . . . . . . . . . . . . . . . . . . . . . 7 4.4. Option Usage . . . . . . . . . . . . . . . . . . . . . . . 8 5. Mobile Node/host behavior . . . . . . . . . . . . . . . . . . 9 6. Access Router/NAS/DHCP relay agent behavior . . . . . . . . . 10 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . . 13 9.2. Informative References . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Patil, et al. Expires September 9, 2009 [Page 2] Internet-Draft APN and ATTACH_Type Options March 2009 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]. Patil, et al. Expires September 9, 2009 [Page 3] Internet-Draft APN and ATTACH_Type Options March 2009 2. Introduction Cellular data networks which are based on 3GPP standards [TS-23.060], i.e GPRS (General Packet Radio Service) define the concept of an Access Point Name (APN). The APN is an FQDN and identifies a specific gateway in the core network. Operators choose to offer different types of services via specific gateways. For example gateway 1 identified by APN1 offers Internet connectivity while gateway 2 identified by APN2 offers multi-media messaging service (MMS). A mobile node which attaches via a 3GPP access network indicates the gateway to which it needs connectivity by including the APN parameter in the network attachment signaling messages. The APN information from the UE received in the attach signaling messages enables the access network to establish a tunnel to the appropriate gateway in the core. The mobile node chooses the APN based on the application in use or policies. The application is configured to connect to the gateway through which the operator provides the service. Proxy Mobile IPv6 [RFC5213] is a network based mobility protocol. A host which is attached to a Proxy MIP6 (PMIP6) domain through an access network of type X may initiate a handover when it attaches to another access network of type Y. In order to ensure that the Local Mobility Agent (LMA) in the PMIP6 domain assigns the host the same prefix/address, the Mobility access gateway (MAG) in the network to which the host performs the handover to (i.e type Y) needs to indicate that it is a handover by setting the flag in the Proxy Binding Update (PBU) mesage sent by the MAG to the LMA . In the absence of any context transfer from the previous MAG to the new MAG, the host has to provide this information to the new MAG. The host can indicate that the network attachment to the access network of type Y is a handover. A multiinterfaced host may attach via a second interface to the same PMIP6 domain via which the host using another interface is already connected. In such cases it is essential to indicate if the new network attachment is to be treated as a handover from the previous interface or is a new session,. This document specifies DHCP options for DHCPv4 and DHCPv6 which enable the host to indicate the gateway identified by an APN to which connectivity is desired and the attach-type indicator to be used in the case of Proxy MIP6. Patil, et al. Expires September 9, 2009 [Page 4] Internet-Draft APN and ATTACH_Type Options March 2009 3. Terminology This document refers to [RFC5213]. The term Access Point Name is defined in [TS-23.003] in section 9.1. It is also defined below as per the 3GPP definition. Access Point Name: In the GPRS backbone, an Access Point Name (APN) is a reference to a GGSN (Gateway GPRS Serving Node). Patil, et al. Expires September 9, 2009 [Page 5] Internet-Draft APN and ATTACH_Type Options March 2009 4. DHCP options for APN and Attach-type The use of APN has been limited to 3GPP networks. In the case of 3GPP accesses such as GERAN, UMTS and HSPA, a layer 2 mechanism is specified which enables the mobile node to indicate the APN parameter to the access network, and thereby being assigned a specific GGSN in the core. Recent developments now allow non-3GPP accesses such as HRPD and WiMAX to also connect to a 3GPP core network. These access types do not have a specific mechanism by which a mobile node can indicate the APN to establish a connection with. Specifying this capability as a DHCP option enables the mobile node to indicate the APN to establish a connection with at the time of network entry. Proxy Mobile IPv6 [RFC5213] does not require any changes on the host in order to support mobility. A Proxy MIP6 domain can span multiple access networks of different technologies. An MN which is attached via an interface (I1) to a PMIP6 domain may attach via another interface (I2). If the MN wants the sessions which are currently served by interface I1 to be moved to interface I2, it needs to indicate that the new network attachment is of type handover. The MN can indicate the attach type via a DHCP option during network entry and the MAG in the PMIP6 domain can use this information in the signaling to the LMA appropriately. 4.1. DHCPv6 Attach Information option This option enables the DHCPv6 host to indicate the access point name to which the connection needs to be established with and whether the connection being established is the handover from another interface or a new attachment. The host (DHCP client) includes this option in the DHCP Request message sent to the access gateway/NAS (Network Access Server) which acts as the DHCP server or relay. The format of the DHCPv6 OPTION_ATTACH_INFO is: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_ATTACH_INFO | Option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attach_Info_Data... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Patil, et al. Expires September 9, 2009 [Page 6] Internet-Draft APN and ATTACH_Type Options March 2009 Option-code OPTION_ATTACH_INFO To be assigned by IANA Option-len The length of the Attach_Info_Data in units of octets Attach_Info_Data see section Section 4.3 4.2. DHCPv4 Attach Information option This option enables the DHCPv4 host to indicate the access point name to which the connection needs to be established with and whether the connection being established is the handover from another access network or a new attachment. The host (DHCP client) includes this option in the DHCP Request message sent to the access gateway/NAS (Network Access Server) which acts as the DHCP server or relay. The format of the DHCPv4 ATTACH_INFO option is: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ATTACH_INFO | length | Attach_Info_Data... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Option-code ATTACH_INFO To be assigned by IANA Option-len The length of the ATTACH_INFO option is variable, it is given in units of octets Attach_Info_Data see section Section 4.3 4.3. Attach Info Data The Attach_Info_Data defines a common layout shared by both the DHCPv6 and DHCPv4 Attach Information options. It consists of two fields: the Attach_Type and the Access_Point_Name which enable the host to indicate the type of connection required. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attach_Type | Access_Point_Name... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Patil, et al. Expires September 9, 2009 [Page 7] Internet-Draft APN and ATTACH_Type Options March 2009 Attach_Type The Attach_Type specifies the following values: Handover: 0 New Service Flow: 1 Reserved: 2-255 Access_Point_Name The Access_Point_Name indicates the network node providing the service to the host The Attach_Type field enables the host to indicate if the attach to the network is to be interpreted as a handover or establishment of a new connection. This is applicable in the case the host is attaching to a PMIP6 domain. The Access_Point_Name field enables the host to indicate the APN to which the connection needs to be established with. It is formatted as a character string consisting of characters from the NVT ASCII character set and it SHOULD NOT contain the trailing NULL in accordance with section 2 of [RFC2132]. The host (DHCP client) includes the Attach_Type and Access_Point_Name in the DHCP Request message sent to the Access Router/Mobility Access Gateway which acts as a DHCP relay or in some cases a DHCP server. The MAG uses the ATTACH_Type to construct the signaling message to the Local Mobility Agent as per [RFC5213] . The MAG uses the Access_Point_Name to select the correct LMA which provides the service requested by the host. 4.4. Option Usage The requesting and sending of the proposed DHCP options follows the rules specified in [RFC3315] for DHCPv6 options and in [RFC2131] for DHCPv4 options. Patil, et al. Expires September 9, 2009 [Page 8] Internet-Draft APN and ATTACH_Type Options March 2009 5. Mobile Node/host behavior A mobile node includes the Attach Information option when attaching to an access network which is served by a 3GPP core. The option is not required for access technologies which have layer 2 mechanisms for conveying the APN and the attach type. The MN/host is aware of the access type through which it is connecting and hence can make the decision to include the Attach Information option. The MN includes the Attach Information Option in the DHCP Request message sent to the access router/NAS. The MN is aware when it attaches via another access type if it is to be treated as a handover. If the MN prefers to move the sessions from the previous interface to the new interface it needs to indicate that it is a handover by appropriately setting the Attach_Type in the Attach Information option. Patil, et al. Expires September 9, 2009 [Page 9] Internet-Draft APN and ATTACH_Type Options March 2009 6. Access Router/NAS/DHCP relay agent behavior An access router/gateway which also acts as a NAS and includes either a DHCP relay function or in some cases acts as a DHCP server receives the DHCP request message which includes Attach Information option. The gateway uses the Access_Point_Name from the Attach Information option to establish a bi-directional tunnel with the appropriate gateway in the 3GPP core network. The NAS/gateway resolves the IP address of the gateway in the core from the APN via DNS. The NAS/access gateway which receives the Attach Information option from the MN in the DHCP Request relays this information to the PMIP6 MAG function. The MAG uses the Attach_Type from the Attach Information option to set the flags in the proxy binding update (PBU) sent to the Local Mobiliity agent (LMA). Patil, et al. Expires September 9, 2009 [Page 10] Internet-Draft APN and ATTACH_Type Options March 2009 7. Security Considerations The options specified in this I-D do not introduce any security vulnerabilities which are new. Patil, et al. Expires September 9, 2009 [Page 11] Internet-Draft APN and ATTACH_Type Options March 2009 8. IANA Considerations IANA is requested to assign the option codes for the DHCPv4 Attach Information option and for the DHCPv6 Attach Information option. 3GPP TS 23.060 v 5.2.0, "General Packet Radio Service (GPRS); Service description; Stage 2(Release 5)", June 2002. Patil, et al. Expires September 9, 2009 [Page 12] Internet-Draft APN and ATTACH_Type Options March 2009 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. 9.2. Informative References [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [TS-23.003] "3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Numbering, addressing and identification (Release 8)", 3GPP TS 23.003 v 8.3.0, December 2008. [TS-23.060] "General Packet Radio Service (GPRS); Service description; Stage 2 (Release 8)", 3GPP TS 23.060 v 8.3.0, December 2008. Patil, et al. Expires September 9, 2009 [Page 13] Internet-Draft APN and ATTACH_Type Options March 2009 Authors' Addresses Basavaraj Patil Nokia 6021 Connection Drive Irving, TX 75039 USA Email: basavaraj.patil@nokia.com Kuntal Chowdhury Starent Networks 20 International Place Tewksbury, MA 01876 USA Email: kchowdhury@starentnetworks.com Domagoj Premec Nokia Siemens Networks Heinzelova 70a Zagreb, 10000 Croatia Phone: +395 (1) 6105 293 Email: domagoj.premec.ext@nsn.com Patil, et al. Expires September 9, 2009 [Page 14]