PCP Working Group G. Chen Internet-Draft China Mobile Intended status: Standards Track T. Reddy Expires: March 22, 2014 P. Patil Cisco M. Boucadair France Telecom September 18, 2013 PCP Server Discovery in Mobile Networks with SIPTO draft-chen-pcp-sipto-serv-discovery-00 Abstract This document proposes an extension to DHCPv4 Relay information so that a PCP client learns the relevant PCP server deployed in the context of traffic offload. 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 March 22, 2014. Copyright Notice Copyright (c) 2013 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 (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 Chen, et al. Expires March 22, 2014 [Page 1] Internet-Draft PCP Server Discovery with SIPTO September 2013 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. DHCPv4 Relay Agent . . . . . . . . . . . . . . . . . . . . . 3 3.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Relay Agent behavior . . . . . . . . . . . . . . . . . . 4 3.3. DHCPv4 Server behavior . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 7. Change History . . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . 5 8.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction Given the exponential growth in the mobile data traffic, Mobile Operators are investigating solutions to offload some of the IP traffic flows at the nearest access edge that has an Internet interconnection point. This approach results in efficient usage of the mobile packet core and helps lower the transport cost. Since Release 10, 3GPP starts supporting of Selected IP Traffic Offload (SIPTO) function defined in [TS23.060], [TS23.401]. The SIPTO function described in [TS23.060] allows an operator to offload certain types of traffic at a network node close to the UE's point of attachment to the access network. Traffic Offload Function(TOF) has been defined to make such decisions and enforces NAT for those traffic. The traffic would go through the Mobile Packet Core only if the flow identification doesn't match TOF filters. SIPTO architecture is also explained in [I-D.chen-pcp-mobile-deployment]. [I-D.ietf-pcp-dhcp] specifies DHCP (IPv4 and IPv6) options to communicate Port Control Protocol (PCP) Server addresses to hosts. However, PCP Client on the mobile node will not know whether a flow will traverse the Mobile Packet Core or will get offloaded at the TOF and hence will not know which PCP server to send its requests to. Even if the mobile node learns its PCP server using DHCP, it will only learn about the PCP server in the Mobile Packet Core since the source of information is the DHCP server in the Mobile Packet Core. The mobile node may never learn the presence of the PCP server at Chen, et al. Expires March 22, 2014 [Page 2] Internet-Draft PCP Server Discovery with SIPTO September 2013 TOF. This requires TOF to act as a PCP Proxy for the PCP server in the Mobile Packet Core and as a PCP server for the offloaded traffic at the TOF. However, this alone does not solve this problem since the mobile node needs to be informed of the PCP proxy on the TOF. This document proposes an extension to DHCPv4 Relay Information Option to achieve this objective. This will also ensure that the PCP client will only learn the PCP server address of the TOF. Note: o The SIPTO problem can be addressed for IPv6 either by using NPTv6 [RFC6296] or associating the mobile device with multiple IPv6 prefixes (one prefix to offload the traffic and other one provided by the Mobile Packet Core for IP Mobility, access to Application Servers in Mobile Packet Core etc). New DHCPv6 Relay Agent PCP Server option will only be required if NPTv6 is used to offload the traffic. However if multiple IPv6 prefixes are assigned to the mobile device then it can use the mechanism explained in [I-D.ietf-pcp-server-selection] to contact multiple PCP servers. o The proposed extension to DHCPv4 Relay Information Option in this document is also useful to solve problems in other deployments like PMIPv6 [RFC5213] where mobile access gateway can selectively offload some of the IPv4 traffic flows in the access network instead of tunneling back to the local mobility anchor in the home network [RFC6909]. 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]. 3. DHCPv4 Relay Agent When DHCPv4 Relay Agent [RFC3046] is co-located with the TOF, the proposal is for the relay agent to influence the DHCPv4 Server to opt for the PCP server address proposed by the Relay Agent over the one configured on the DHCPv4 Server. The DHCPv4 Relay Agent will insert a new suboption under relay agent information option indicating the IP address of the appropriate PCP server/proxy. For this to happen, the UE MUST ensure that it includes OPTION_PCP_SERVER in the Parameter Request List Option in the DHCPv4 Discover/Request message. 3.1. Format Chen, et al. Expires March 22, 2014 [Page 3] Internet-Draft PCP Server Discovery with SIPTO September 2013 To realize the mechanism described above, the document proposes a new PCP Server suboption for the DHCPv4 relay agent information option that carries the IP address of PCP Server. If a PCP server is associated with more than one IP address, all those IP addresses can be listed as part of this option. If there is more than one PCP server, there will be multiple instances of this option each corresponding to a PCP server. Code Length PCP IP address +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ | TBA | n | a1 | a2 | a3 | a4 | a1 | a2 | a3 | a4 | ... +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ Code: TBA Length: Includes the length of the "PCP Server IP address" field in octets; The maximum length is 255 octets. The length should be multiple of 4. PCP Server IP address: The IP address of the PCP Server to be used by the PCP Client when issuing PCP messages. 3.2. Relay Agent behavior A DHCPv4 relay agent MAY be configured to include a PCP Server suboption in relayed DHCPv4 messages. If the source IP address in the DHCPv4 request matches the TOF filter configuration then the PCP Server IP address SHOULD be inserted into the PCP Server suboption. The PCP Server IP address is determined through mechanisms outside the scope of this document. 3.3. DHCPv4 Server behavior The proposed suboption provides additional information to the DHCP server. Upon receiving a DHCPv4 Discover/Request containing the suboption, the DHCPv4 server, if configured to support this suboption, MUST populate the DHCPv4 Offer/Ack with the suggested PCP server IP address overriding any other PCP server IP address configuration that it may already have. There is no special additional processing for this suboption. 4. Security Considerations The security considerations in [RFC6887] , [I-D.ietf-pcp-proxy] and section 5 of [RFC3046] also apply to this use. Chen, et al. Expires March 22, 2014 [Page 4] Internet-Draft PCP Server Discovery with SIPTO September 2013 5. IANA Considerations Authors of this document request IANA to assign a suboption number for the PCP Server Suboption from the DHCP Relay Agent Information Option [RFC3046] suboption number space. 6. Acknowledgements TODO 7. Change History [Note to RFC Editor: Please remove this section prior to publication.] 8. References 8.1. Normative References [I-D.ietf-pcp-dhcp] Boucadair, M., Penno, R., and D. Wing, "DHCP Options for the Port Control Protocol (PCP)", draft-ietf-pcp-dhcp-08 (work in progress), August 2013. [I-D.ietf-pcp-proxy] Boucadair, M., Penno, R., and D. Wing, "Port Control Protocol (PCP) Proxy Function", draft-ietf-pcp-proxy-04 (work in progress), July 2013. [I-D.ietf-pcp-server-selection] Boucadair, M., Penno, R., Wing, D., Patil, P., and T. Reddy, "PCP Server Selection", draft-ietf-pcp-server- selection-01 (work in progress), May 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3046] Patrick, M., "DHCP Relay Agent Information Option", RFC 3046, January 2001. [RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, April 2013. 8.2. Informative References [I-D.chen-pcp-mobile-deployment] Chen, et al. Expires March 22, 2014 [Page 5] Internet-Draft PCP Server Discovery with SIPTO September 2013 Chen, G., Cao, Z., Boucadair, M., Ales, V., and L. Thiebaut, "Analysis of Port Control Protocol in Mobile Network", draft-chen-pcp-mobile-deployment-04 (work in progress), July 2013. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix Translation", RFC 6296, June 2011. [RFC6909] Gundavelli, S., Zhou, X., Korhonen, J., Feige, G., and R. Koodli, "IPv4 Traffic Offload Selector Option for Proxy Mobile IPv6", RFC 6909, April 2013. [TS23.060] 3GPP, ., ""General Packet Radio Service (GPRS); Service description; Stage 2", June 2012.", September 2012. [TS23.401] 3GPP, ., "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E- UTRAN) access (Release 11), 3GPP TS 23.401, V11.2.0 (2012- 06).", September 2012. Authors' Addresses Gang Chen China Mobile No.32 Xuanwumen West Street Xicheng District Beijing 100053 China Email: phdgang@gmail.com Tirumaleswar Reddy Cisco Systems, Inc. Cessna Business Park, Varthur Hobli Sarjapur Marathalli Outer Ring Road Bangalore, Karnataka 560103 India Email: tireddy@cisco.com Chen, et al. Expires March 22, 2014 [Page 6] Internet-Draft PCP Server Discovery with SIPTO September 2013 Prashanth Patil Cisco Systems, Inc. Bangalore India Email: praspati@cisco.com Mohamed Boucadair France Telecom Rennes 35000 France Email: mohamed.boucadair@orange.com Chen, et al. Expires March 22, 2014 [Page 7]