Port Control Protocol (PCP) Extension for Port Set Allocation
Author(s): Tina Tsou, Qiong Sun, Cathy Zhou, Senthil Sivakumar, Mohamed Boucadair, Simon Perreault
This document defines an extension to PCP allowing clients to manipulate sets of ports as a whole. This is accomplished by a new MAP option: PORT_SET....
Internet Engineering Task Force Q. Sun Internet-Draft China Telecom Intended status: Standards Track M. Boucadair Expires: August 26, 2013 France Telecom S. Sivakumar Cisco Systems C. Zhou Huawei Technologies T. Tsou Huawei Technologies (USA) S. Perreault Viagenie February 22, 2013 Port Control Protocol (PCP) Extension for Port Set Allocation draft-tsou-pcp-natcoord-10 Abstract This document defines an extension to PCP allowing clients to manipulate sets of ports as a whole. This is accomplished by a new MAP option: PORT_SET. 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 26, 2013. 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 Sun, et al. Expires August 26, 2013 [Page 1] Internet-Draft PCP PORT_SET February 2013 (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 . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Lightweight 4over6 . . . . . . . . . . . . . . . . . . . 2 1.2. Applications Using Port Sets . . . . . . . . . . . . . . 3 1.3. Firewall Control . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. The need for PORT_SET . . . . . . . . . . . . . . . . . . . . 3 4. The PORT_SET Option . . . . . . . . . . . . . . . . . . . . . 4 4.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 5 4.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 6 4.3. Port Set Renewal and Deletion . . . . . . . . . . . . . . 6 5. Operational Considerations . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 8. Authors List . . . . . . . . . . . . . . . . . . . . . . . . 7 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 10.1. Normative References . . . . . . . . . . . . . . . . . . 9 10.2. informative References . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction This section describes a few (and non-exhaustive) envisioned use cases. Note that the PCP extension defined in this document is generic and is expected to be applicable to other use cases. 1.1. Lightweight 4over6 In the Lightweight 4over6 [I-D.cui-softwire-b4-translated-ds-lite] architecture, shared global addresses can be allocated to customers. It allows moving the Network Address Translation (NAT) function, otherwise accomplished by a Carrier-Grade NAT (CGN) [I-D.ietf-behave-lsn-requirements], to the Customer-Premises Equipment (CPE). This provides more control over the NAT function to the user, and more scalability to the ISP. In the lw4o6 architecture, the PCP-controlled device corresponds to the lwAFTR, and the PCP client corresponds to the lwB4. The client Sun, et al. Expires August 26, 2013 [Page 2] Internet-Draft PCP PORT_SET February 2013 sends a PCP MAP request containing a PORT_SET option to trigger shared address allocation on the lwAFTR. The PCP response contains the shared address information, including the port set allocated to the lwB4. 1.2. Applications Using Port Sets Some applications require not just one port, but a port set. One example is a Session Initiation Protocol (SIP) User Agent Server (UAS) [RFC3261] expecting to handle multiple concurrent calls, including media termination. When it receives a call, it needs to signal media port numbers to its peer. Generating individual PCP MAP requests for each of the media ports during call setup would introduce unwanted latency. Instead, the server can pre-allocate a set of ports such that no PCP exchange is needed during call setup. Using PORT_SET, an application can manipulate port sets much more efficiently than with individual MAP requests. 1.3. Firewall Control Port sets are often used in firewall rules. For example, defining a range for RTP [RFC3550] traffic is common practice. The MAP request can already be used for firewall control. The PORT_SET option brings the additional ability to manipulate firewall rules operating on port sets instead of single ports. 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 [RFC 2119]. 3. The need for PORT_SET Multiple MAP requests can be used to manipulate a set of ports, having roughly the same effect as a single use of a MAP request with a PORT_SET option. However, use of the PORT_SET option is more efficient when considering the following aspects: Network Traffic: A single request uses less network resources than multiple requests. Latency: Even though MAP requests can be sent in parallel, we can expect the total processing time to be longer for multiple requests than a single one. Sun, et al. Expires August 26, 2013 [Page 3] Internet-Draft PCP PORT_SET February 2013 Client-side simplicity: The logic that is necessary for maintaining a set of ports using a single port set entity is much simpler than that required for maintaining individual ports, especially when considering failures, retransmissions, lifetime expiration, and re-allocations. Server-side efficiency: Some PCP-controlled devices can allocate port sets in a manner such that data passing through the device is processed much more efficiently than the equivalent using individual port allocations. For example, a CGN having a "bulk" port allocation scheme (see [I-D.ietf-behave-lsn-requirements] section 5) often has this property. Server-side scalability: The number of mapping entries in PCP- controlled devices is often a limiting factor. Allocating port sets in a single request can result in a single mapping entry being used, therefore allowing greater scalability. Therefore, while it is functionally possible to obtain the same results using plain MAP, the extension proposed in this document allows greater efficiency, scalability, and simplicity, while lowering latency and necessary network traffic. In a nutshell, PORT_SET is a necessary optimization. In addition, PORT_SET supports parity preservation. Some protocols (e.g. RTP [RFC3550]) assign meaning to a port number's parity. When mapping sets of ports for the purpose of using such kind of protocol, preserving parity can be necessary. 4. The PORT_SET Option Option Name: PORT_SET Number: TBD Purpose: To map sets of ports. Valid for Opcodes: MAP Length: 2 bytes May appear in: Both requests and responses Maximum occurrences: 1 NOTE TO IANA (to be removed prior to publication as an RFC): The number is to be assigned by IANA in the range 1-63 (i.e., mandatory to process and created via Standards Action). Sun, et al. Expires August 26, 2013 [Page 4] Internet-Draft PCP PORT_SET February 2013 The PORT_SET Option indicates that the client wishes to reserve a set of ports. The requested number of ports in that set is indicated in the option. The PORT_SET Option is formatted as shown in Figure 1. 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 Code=? | Reserved |P| Option Length=2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Port Set Size | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: PORT_SET Option The fields are as follows: P: 1 if parity preservation is requested, 0 otherwise. Port Set Size: Number of ports requested. MUST NOT be zero nor one. NOTE: In its current form, PORT_SET does not support allocating discontinuous port sets. That feature could be added in the future depending on input from the working group. The Internal Port Set is defined as being the range of Port Set Size ports starting from the Internal Port. The External Port Set is respectively defined as being the range of Port Set Size ports starting from the Assigned External Port. The two ranges always have the same size (i.e., the Port Set Size returned by the server). 4.1. Client Behavior To retrieve a set of ports, the PCP client adds a PORT_SET option to its PCP MAP request. If port preservation is required, the PCP Client MUST set the parity bit (to 1) to ask the server to preserve the port parity (i.e., the Assigned External Port and Internal Port have the same parity). The PCP client MUST indicate a suggested Port Set Size. A non-null value MUST be used. The PCP Client MUST NOT include more than one PORT_SET option in a MAP request. If several port sets are needed, the PCP client MUST issue as many MAP requests each of them include a PORT_SET option. These individual MAP request MUST include distinct Internal Port. If the PORT_SET option is not supported by the server, the PCP client will have to issue individual MAP requests with no PORT_SET option. Sun, et al. Expires August 26, 2013 [Page 5] Internet-Draft PCP PORT_SET February 2013 4.2. Server Behavior In addition to regular MAP request processing, the following checks are made upon receipt of a PORT_SET option with non-zero Requested Lifetime: o If multiple PORT_SET options are present in a single MAP request, a MALFORMED_OPTION error is returned. o If the Port Set Size is zero or one, a MALFORMED_OPTION error is returned. If the PREFER_FAILURE option is present and the server is unable to map all ports in the requested External Port Set or is unable to preserve parity (P = 1), the CANNOT_PROVIDE_EXTERNAL error is returned. If the PREFER_FAILURE option is absent, the server MAY map fewer ports than the value of Port Set Size from the request. It MUST NOT map more ports than the client asked for. In any case, the Internal Port Set MUST always begin from the Internal Port indicated by the client. In particular, if the port mapping failed either because of the unavailability of ports, the PCP Server SHOULD reserve only one external port (i.e., the PCP server ignores the PORT_SET option). If the server ends up mapping only a single port, for any reason, the PORT_SET option MUST NOT be present in the response. If the PREFER_FAILURE option is absent and port parity preservation is requested (P = 1), the server MAY preserve port parity. In that case, the External Port is set to a value having the same parity as the Internal Port. If a mapping already exists and the PORT_SET option can be honored, the PCP server updates the mapping with port set information and sends back a positive answer to the requesting PCP client. If the mapping is successful, the MAP response's Assigned External Port is set to the first port in the External Port Set, and the PORT_SET option's Port Set Size is set to number of ports in the mapped port set. 4.3. Port Set Renewal and Deletion Port set mappings are renewed and deleted as a single entity. That is, the lifetime of all port mappings in the set is set to the Assigned Lifetime at once. Sun, et al. Expires August 26, 2013 [Page 6] Internet-Draft PCP PORT_SET February 2013 The PORT_SET option MUST be present in a renewal or deletion request. If a server receives a MAP request without a PORT_SET option and whose Internal Port is inside a mapped Internal Port Set, it replies with a MALFORMED_REQUEST error. 5. Operational Considerations It is totally up to the PCP server to determine the port-set quota for each PCP client. In addition, when the PCP-controlled device supports multiple port-sets delegation for a given PCP client, the PCP client MAY re-initiate a PCP request to get another port set when it has exhausted all the ports within the port-set. If the PCP server is configured to allocate multiple port-set allocation for one subscriber, the same Assigned External IP Address SHOULD be assigned to one subscriber in multiple port-set requests. To optimize the number of mapping entries maintained by the PCP server, it is RECOMMENDED to configure the server to assign the maximum allowed port set in a single response. This policy SHOULD be configurable. The failover mechanism in MAP [section 14 in [I-D.ietf-pcp-base]] and [I-D.boucadair-pcp-failure] can also be applied to port sets. 6. Security Considerations It is believed that no additional security considerations beyond those discussed in [I-D.ietf-pcp-base] apply to this extension. 7. IANA Considerations IANA shall allocate a code in the range 1-63 for the new PCP option defined in Section 4. 8. Authors List The following are extended authors who contributed to the effort: Yunqing Chen China Telecom Room 502, No.118, Xizhimennei Street Beijing 100035 P.R.China Sun, et al. Expires August 26, 2013 [Page 7] Internet-Draft PCP PORT_SET February 2013 Chongfeng Xie China Telecom Room 502, No.118, Xizhimennei Street Beijing 100035 P.R.China Yong Cui Tsinghua University Beijing 100084 P.R.China Phone: +86-10-62603059 Email: email@example.com Qi Sun Tsinghua University Beijing 100084 P.R.China Phone: +86-10-62785822 Email: firstname.lastname@example.org Gabor Bajko Nokia Email: email@example.com Xiaohong Deng France Telecom Email: firstname.lastname@example.org 9. Acknowledgements Sun, et al. Expires August 26, 2013 [Page 8] Internet-Draft PCP PORT_SET February 2013 The authors would like to show sincere appreciation to Alain Durand, Dan Wing, Dave Thaler, Reinaldo Penno, Sam Hartman, and Yoshihiro Ohba, for their useful comments and suggestions. 10. References 10.1. Normative References [I-D.ietf-pcp-base] Wing, D., "Port Control Protocol (PCP)", October 2012. [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 10.2. informative References [I-D.boucadair-pcp-failure] Boucadair, M., Dupont, F., and R. Penno, "Port Control Protocol (PCP) Failure Scenarios", August 2012. [I-D.cui-softwire-b4-translated-ds-lite] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., and Y. Lee, "Lightweight 4over6: An Extension to DS-Lite Architecture", Feb 2012. [I-D.ietf-behave-lsn-requirements] Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A., and H. Ashida, "Common requirements for Carrier Grade NATs (CGNs)", draft-ietf-behave-lsn-requirements-10 (work in progress), December 2012. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC3261, June 2002. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC3550, July 2003. Authors' Addresses Qiong Sun China Telecom P.R.China Phone: 86 10 58552936 Email: email@example.com Sun, et al. Expires August 26, 2013 [Page 9] Internet-Draft PCP PORT_SET February 2013 Mohamed Boucadair France Telecom Rennes 35000 France Email: firstname.lastname@example.org Senthil Sivakumar Cisco Systems 7100-8 Kit Creek Road Research Triangle Park, North Carolina 27709 USA Phone: +1 919 392 5158 Email: email@example.com Cathy Zhou Huawei Technologies Bantian, Longgang District Shenzhen 518129 P.R. China Email: firstname.lastname@example.org Tina Tsou Huawei Technologies (USA) 2330 Central Expressway Santa Clara, CA 95050 USA Phone: +1 408 330 4424 Email: Tina.Tsou.Zouting@huawei.com Simon Perreault Viagenie 246 Aberdeen Quebec, QC G1R 2E1 Canada Phone: +1 418 656 9254 Email: email@example.com Sun, et al. Expires August 26, 2013 [Page 10]