HTTP/1.1 200 OK Date: Tue, 09 Apr 2002 01:44:43 GMT Server: Apache/1.3.20 (Unix) Last-Modified: Thu, 25 Feb 1999 17:17:00 GMT ETag: "2ed6e7-1d3a-36d5858c" Accept-Ranges: bytes Content-Length: 7482 Connection: close Content-Type: text/plain Internet Engineering Task Force Henry Houh INTERNET DRAFT NBX Corporation February 25, 1999 Expires August 25, 1999 DHCP Options for Call Control Servers 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.'' To learn the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (North Europe), ftp.nis.garr.it (South Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast). This document is a submission to the Dynamic Host Configuration Working Group of the Internet Engineering Task Force (IETF). Comments should be submitted to the dhcp-v4@bucknell.edu mailing list. Distribution of this memo is unlimited. Abstract This document defines a new DHCP option for delivering configuration information to telephony enabled hosts in order to locate a call control/signalling server. The option carries several operational parameters that allow multiple call control vendors to utilize this field. 1. Introduction Telephony is emerging as a network-based application. The Call Control Server option allows telephony or gateway devices which cannot independently setup up and signal calls to automatically discover an address of a call control server. This specification describes a DHCP option [1] that can carry one or several Call Control Server sub-options. Each sub-option is treated as a separate potential call control server by the hosts. Houh Expires August 25, 1999 [Page 1] Internet Draft DHCP Option for Call Control Servers November 1998 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. [2] 2. Call Control Server Option This option specifies one or more fields carrying Call Control Server information. The fields that can be carried by this option are described in the sections that follow. The code for this option is TBD, and its maximum length is 255 octets. Code Len Sub-Option 1 Sub-Option 2 +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-- | TBD | n | a1 | a2 | a3 | a4 | a1 | a2 | a3 | a4 | ... +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-- The 'Len' field specifies the number of octets containing sub-option information within the DHCP option. Each sub-option will contain a code followed by a length that specifies the number of octets containing configuration parameter information within the sub-option. Sub Sub Code Len Configuration Parameter(s) +-----+-----+-----+-----+-----+-----+-----+-----+-- | x | n | a1 | a2 | a3 | a4 | a6 | a7 | ... +-----+-----+-----+-----+-----+-----+-----+-----+-- 2.1. Call Control Servers This section describes the vendor-specific sub-options. Other types/vendors of call control servers can be added by using new sub-option fields. See section 2.2 for the procedure for adding sub-option fields. 2.1.1 NBX Call Control Server Sub-option This sub-option specifies the network address of an NBX Call Control Server. The code for this sub-option is 1. The length specified in the 'Len' field of this sub-option MUST always be 4 octets. Code Len NBX Server Address +-----+-----+-----+-----+-----+-----+ | 1 | 4 | a1 | a2 | a3 | a4 | +-----+-----+-----+-----+-----+-----+ Houh Expires August 25, 1999 [Page 2] Internet Draft DHCP Option for Call Control Servers November 1998 2.1.2 3Com Call Control Server This sub-option specifies the network address of a 3Com Call Control Server. The code for this sub-option is 2. The length specified in the 'Len' field of this sub-option MUST always be 4 octets. Code Len 3Com Server Address +-----+-----+-----+-----+-----+-----+ | 2 | 4 | a1 | a2 | a3 | a4 | +-----+-----+-----+-----+-----+-----+ 2.1.3 MEGACO MGC This sub-option specifies the network address of a MEGACO Media Gateway Controller. The code for this sub-option is 3. The length specified in the 'Len' field of this sub-option MUST always be 4 octets. Code Len MEGACO MGC Address +-----+-----+-----+-----+-----+-----+ | 3 | 4 | a1 | a2 | a3 | a4 | +-----+-----+-----+-----+-----+-----+ 2.2 Procedure for adding call control server types A vendor may add a new sub-option field by issuing an internet draft that contains the new sub-option. The new sub-option field code MUST be labeled "TBD." This draft will then be submitted to the DHC working group, and, if accepted for inclusion in the DHCP specification, a sub-option field code is assigned and the sub-option specification is published as an RFC which updates this RFC. 3. Using Multiple Sub-options More than one sub-option field MAY be returned to the host. In addition, more than one of any sub-option type MAY be present. This allows the host to select the call control server appropriate to own its signaling protocol, allowing a single DHCP server to support multiple homogeneous call control servers as well as heterogeneous telephony and gateway devices. 4. References [1] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC-2132, March 1997. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC-2119, March 1997. Houh Expires August 25, 1999 [Page 3] Internet Draft DHCP Option for Call Control Servers November 1998 [3] Droms, R., "Dynamic Host Configuration Protocol", RFC-2131, March 1997. 5. Security Considerations DHCP currently provides no authentication or security mechanisms. Potential exposures to attack are discussed in section 7 of the DHCP protocol specification [3]. In particular, these DHCP options allow an unauthorized DHCP server to misdirect a telephone or gateway host to an unauthorized call control server. 6. Author's Address Henry Houh NBX Corporation 100 Brickstone Square Andover, MA 01810 Phone: +1 978 740 0000 x257 EMail: hhouh@nbxcorp.com Houh Expires August 25, 1999 [Page 4]