DHC Lu Huang Internet Draft Hui Deng Intended status: Informational China Mobile Expires: April 18, 2010 October 19, 2009 DHCP option including Multiple Relay Agents' Information draft-huang-dhc-multiple-relay-agents-option-00.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 April 19, 2010. 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. Huang, et al. Expires April 18, 2010 [Page 1] Internet-Draft Option including Multiple Agents' Information Oct. 2009 Abstract RFC 3046 allows only the first Relay Agent to append Relay Agent Information option. In some networks, both Layer 2 Relay Agents and Layer 3 Relay Agents are deployed and their information is necessary for DHCP packets forwarding and DHCP server's policy designing described as [4]. This document defines a DHCP option which can contain multiple relay agents' information and describes how it works. Table of Contents 1. Introduction......................................... 2 2. DHCP option including Multiple Relay Agents' Information .... 3 2.1. Mechanism....................................... 3 2.2. Format ......................................... 4 3. Security Considerations................................ 5 4. IANA Considerations................................... 5 5. References.......................................... 5 5.1. Normative References.............................. 5 5.2. Informative References............................ 5 Author's Addresses...................................... 6 1. Introduction As defined in RFC 3046, Relay Agent Information option is inserted by the DHCP relay agent (or downstream network element) when forwarding client-originated DHCP packets to a DHCP server. Servers recognizing the Relay Agent Information option may use the information to implement IP address or other parameter assignment policies. The DHCP Server echoes the option back verbatim to the relay agent in server- to-client replies, and the relay agent strips the option before forwarding the reply to the client. RFC 3046 allows only one agent add its information with option 82. But in some scenarios as [4], multiply relay agents need to insert more information into the same DHCP message. This document defines a DHCP option which can contain multiple relay agents' information and describes how it works. Huang, et al. Expires April 18, 2010 [Page 2] Internet-Draft Option including Multiple Agents' Information Oct. 2009 2. DHCP option including Multiple Relay Agents' Information 2.1. Mechanism This option is organized as a single DHCP option that contains one or more sub-options. Each relay agent can insert a set of sub-options to convey its Information. ------- +-----------+ +-----------+ /// \\\ +------+ +------+ |Layer 2 | |Layer 3 | | | |DHCP | |Client+--+Relay Agent+--+Relay Agent+--+ Network +--+Server| +------+ +-----------+ +-----------+ | | +------+ \\\ /// ------- Figure 1 Network Scenario As shown in figure 1, it's a most popular network scenario where option including Multiple Relay Agents' Information is necessary. Based on the demand of the new Relay Agent Information option as [4], this option works as following: 1. An initiating client sends a DHCP discovery packet. 2. Layer 2 relay agent receives the discovery packet without any options defined in this document. So it inserts a new option in which a set of sub-options convey the layer 2 relay agent's necessary information. After that, the discovery packet is forwarded to the appropriate port. 3. Layer 3 relay agent receives the discovery packet and check out that it already contains a relay agent information option defined in this document. So it just insert a set of sub-options into the existing option to convey its own necessary information. After that, the discovery packet is forwarded and reaches DHCP server directly or through a network. 4. DHCP server handles the discovery packet as normal and could carry out flexible IP assigning or other policies based on the information of option defined in this document. After that DHCP server reply a DHCP response packet containing the original option carried in the corresponding discovery packet. 5. Layer 3 relay agents quickly get the right outgoing interface based on the information in the option and forward the response packet after deleting its set of sub-options. Huang, et al. Expires April 18, 2010 [Page 3] Internet-Draft Option including Multiple Agents' Information Oct. 2009 6. Layer 2 relay agents quickly get the right outgoing interface based on the information in the option and forward the response packet. Because there is no other agent's information left in the option, so in this case layer 2 relay agent delete the whole option before forwarding the packet. 2.2. Format Option format: +-------+-----+-----+ |Code(x)| Len |Value| +-------+-----+-----+ This option use a new DHCP option code "x". Value: +-----------+-----------+-----------+-----------+ |sub-option1|sub-option2|sub-option3|sub-option4| +-+--+------+-+--+------+-+--+------+-+--+------+ |1|N1|value1|2|N2|value2|3|N3|value3|4|N4|value4|->a Set of sub-options +-+--+------+-+--+------+-+--+------+-+--+------+ / ... \ | Multiple sets of sub-options | \ ... / +-+--+------+-+--+------+-+--+------+-+--+------+ |1|N1|value1|2|N2|value2|3|N3|value3|4|N4|value4| +-+--+------+-+--+------+-+--+------+-+--+------+ Sub-option1 Agent level. Describe the order of agent who insert this set of sub-options. For example, in the case of figure 1, layer 2 relay agent's level is 1 because it is the closest agent to the client and it will be the first agent who insert relay agent information. Sub-option2 Agent ID. Describe a unique identifier for the agent who insert this set of sub-options. Sub-option3 Huang, et al. Expires April 18, 2010 [Page 4] Internet-Draft Option including Multiple Agents' Information Oct. 2009 IP address. Describe IP address of the agent who insert this set of sub-options. For a pure layer 2 agent, this field could be 0.0.0.0. Sub-option4 Downstream interface. Describe the receiving interface of the DHCP packet of the agent who insert this set of sub-options. 3. Security Considerations This document doesn't propose any new protocol. 4. IANA Considerations This document requires a new number for DHCP option code x described in section 2.2. 5. References 5.1. Normative References [1] R. Droms, Bucknell University, "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [2] S. Alexander, Silicon Graphics, Inc., and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [3] M. Patrick, Motorola BCS, "DHCP Relay Agent Information Option", RFC 3046, January 2001. 5.2. Informative References [4] L. Huang, H. Deng, China Mobile, "Problem Statement for DHCP Relay Agent", draft-huang-dhc-relay-ps-00, July 2009. Huang, et al. Expires April 18, 2010 [Page 5] Internet-Draft Option including Multiple Agents' Information Oct. 2009 Author's Addresses Lu Huang China Mobile 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: huanglu@chinamobile.com Hui Deng China Mobile 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: denghui02@gmail.com Huang, et al. Expires April 18, 2010 [Page 6]