Media Gateway Control Protocol (MGCP) Lockstep State Reporting Mechanism
The information below is for an old version of the document that is already published as an RFC.
This is an older version of an Internet-Draft that was ultimately published as RFC 3992.
|Bill Foster , Flemming Andreasen
|2013-03-02 (Latest revision 2003-07-25)
|Intended RFC status
|Became RFC 3992 (Informational)
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Internet Engineering Task Force B. Foster Internet Draft F. Andreasen Document: <draft-foster-mgcp-lockstep-01.txt> Cisco Systems Category: Informational July 2003 Media Gateway Control Protocol (MGCP) Lockstep State Reporting Mechanism Status of this Document 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. Abstract A Media Gateway Control Protocol (MGCP) endpoint that has encountered an adverse failure condition such as being involved in a transient call when a Call Agent failover occurred could be left in a lockstep state such that events are quarantined but not notified. The MGCP package described in this document provides a mechanism for reporting these situations so that the new Call Agent can take the necessary fault recovery procedures. Conventions used in this document 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 . B. Foster, F. Andreasen Informational [Page 1] MGCP Lockstep State Reporting Mechanism July 2003 1. Introduction In the Media Gateway Control Protocol (MGCP) , when an endpoint operating in "step" mode generates a Notify, it will enter the "notification state" where it waits for a response to the Notify. Furthermore, the endpoint must wait for a new NotificationRequest before it can resume event processing. As long as the endpoint is waiting for this NotificationRequest, we say that it is in the lockstep state. An endpoint that is in lockstep state cannot perform any event processing and hence can also not generate any new Notifys. Endpoints should only be in lockstep state for a very short time, however in case of adverse conditions, an endpoint could potentially end in the lockstep state without the Call Agent realizing it. Clearly, this could have very negative consequences in terms of the service provided. The Lockstep package defined in this document defines extensions to the EndpointConfiguration and RestartInProgress commands that allow a Call Agent to request an endpoint to inform it if the endpoint is in the lockstep state for a specified period of time. 2.0. Lockstep Package Package Name: LCK Version: 0 Package Description: The purpose of this package is to provide a mechanism for reporting a condition in which an endpoint has been in the "lockstep state" for a specified period of time. There are two aspects of this package: * The ability for a Call Agent to request endpoints to report if they are in lockstep state. This is done with the EndpointConfiguration command as described in section 2.1. * The reporting mechanism itself, which is done with a new "lockstep" RestartMethod for the RSIP command as described in section 2.2. 2.1. Request to Report Lockstep State The new "lstime" EndpointConfiguration parameter is used by the Call Agent to request the reporting of "lockstep" state. It uses the following ABNF: "LCK/LST:" 0*WSP LSTIME LSTIME = 1*(4DIGIT) where LSTIME is expressed in seconds, with a value ranging from 0 to 999. A value greater than 2*T-HIST (refer to ) is RECOMMENDED. B. Foster, F. Andreasen Informational [Page 2] MGCP Lockstep State Reporting Mechanism July 2003 LSTIME is the amount of time the endpoint is in the lockstep state before reporting. The timer starts when the endpoint enters the lockstep state and is cancelled if the endpoint leaves the lockstep state before the timeout occurs. The value zero is used to turn off reporting. This parameter can be audited using the AuditEndpoint command. 2.2. Lockstep restart Method A new "lockstep" restart method is defined in the "LCK" package. A RestartInProgress (RSIP) will be sent with this RestartMethod if the endpoint has been configured with a non-zero value for LSTIME and that timer has expired. The syntax of the restart method is as per : "RM" ":" 0*(WSP) "LCK/lockstep" RestartDelay (see ) is not used with the "lockstep" RestartMethod. Also, the "lockstep" RestartMethod does not define a service-state, and hence it will never be returned when auditing the RestartMethod. 3.0. IANA Considerations The MGCP package title "Lockstep" with the name "LCK" and version number zero should be registered with IANA as indicated in Appendix C.1 in . 4.0. Security Considerations Section 5 of the base MGCP specification  discusses security requirements for the base MGCP protocol, which apply equally to the package defined in this document. Use of a security Protocol such as IPsec (RFC 2401, RFC 2406) that provides per message authentication and integrity services is required in order to ensure that requests and responses are obtained from authenticated sources and that messages have not been modified. Without such services, gateways and Call Agents are open to attacks. 5.0. Normative References  Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.  F. Andreasen, B. Foster "Media Gateway Control Protocol (MGCP) Version 1.0", RFC 3435, January 2003. Authors' Addresses Bill Foster Phone: +1 250 758 9418 EMail: firstname.lastname@example.org B. Foster, F. Andreasen Informational [Page 3] MGCP Lockstep State Reporting Mechanism July 2003 Flemming Andreasen Cisco Systems 499 Thornall Street, 8th Floor Edison, NJ 08837 EMail: email@example.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION B. Foster, F. Andreasen Informational [Page 4] MGCP Lockstep State Reporting Mechanism July 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. B. Foster, F. Andreasen Informational [Page 5]