DHC Markus Rentschler Internet Draft Hirschmann Electronics Expires: April 2004 November 2003 DHCP Interface Information Option Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 30, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This draft defines a new option to inform the server about the client's physical interface it is connected to. This information may be used together with the relay agent information option (RFC 3046) for the purpose of topology recognition as well as for IP and other parameter assignment policies. Requirements 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. Rentschler Expires April 2004 [Page 1] Internet-Draft DHCP Interface Information Option Oct 2003 1. Introduction The relay agent information option [RFC 3046], which MAY be added by a relay agent to a client's request to the server, MAY contain a Circuit ID sub option that contains the number of the physical interface on which the relay received this client's request. When the client itself is a device with multiple interfaces (for example a Switching Hub), it would be of interest to know which of the client's interfaces is connected to the relay agent or the server. These informations together could then easily be used to detect and display the active topology of the underlying network. To get the information about the client's physical interface to the server, a new option has to be introduced. 2. Interface Information Option The Interface Information Option encodes a client-local identifier (such as a Switching Hub port number) of the interface from which the initial DHCP server-to-client packet was received. This option MAY be added by DHCP clients. Opt Len Interface Information +------+------+------+------+------+------+------+------+-- | TBD | n | c1 | c2 | c3 | c4 | c5 | c6 | ... +------+------+------+------+------+------+------+------+-- The DHCP server SHOULD report the Interface Information Option of current leases in statistical reports, its MIB and in logs. Since the Interface Information Option is local only to a particular client, the Interface Information Option should be qualified with the MAC or IP address that identifies the client. Servers MAY use the Interface Information Option for IP and other parameter assignment policies on the basis of an exact string match. Rentschler Expires April 2004 [Page 2] Internet-Draft DHCP Interface Information Option Nov 2003 3. Description of Operation If a client receives a DHCP message from a server, it SHOULD always send the new Interface Information Option in responding messages to the server. This rule generally applies also to new DHCP message types not yet defined. During the normal four message exchange the Interface Information Option would therefore be sent in the DHCPREQUEST message. If a client receives a DHCPFORCERENEW message, the Interface Information Option SHOULD be sent in the following DHCPREQUEST or DHCPINFORM message. 4. Security Considerations This document does not cover possible security attacks. 5. IANA Considerations The value for the new Interface Information Option must be assigned from the numbering space defined for DHCP options in RFC 2939. 6. References RFC 2131 R. Droms, March 1997, "The Dynamic Host Configuration Protocol", RFC 2132 S.Alexander, R. Droms, March 1997, "DHCP Options and BOOTP vendor Extensions" RFC 2939 R. Droms, September 2000, "Procedures an IANA guidelines for Definition of new DHCP Options and Message Types", RFC 3046, M. Patrick, January 2001, "DHCP Relay Agent Information Option", RFC 3203, Y. T'Joens et. al., December 2001, "DHCP reconfigure extension", Rentschler Expires April 2004 [Page 3] Internet-Draft DHCP Interface Information Option Nov 2003 7. Author's Address Markus Rentschler Hirschmann Electronics GmbH & Co. KG, Neckartenzlingen, Germany. Email: mrentsch@nt.hirschmann.de Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into. Rentschler Expires April 2004 [Page 4]