Browse Prior Art Database

Suppression of MPEG Transport Streams over IP Outputs from a Standby Element in a Redundant System

IP.com Disclosure Number: IPCOM000032470D
Original Publication Date: 2004-Nov-05
Included in the Prior Art Database: 2004-Nov-05
Document File: 6 page(s) / 49K

Publishing Venue

Motorola

Related People

John Sanders: AUTHOR [+3]

Abstract

MPEG transport streams are increasingly being carried over Ethernet rather than the traditional media such as ASI or DS-3. Unlike the traditional media Ethernet, especially at gigabit speeds, does not readily accommodate a simple change over switch to select the output of a redundant pair of transport stream sources (encoders, multiplexers, etc). Therefore when a back up element takes over from the primary following a failure provision must be made to suppress the output of the failed element to prevent contending transport streams being delivered to the destination element or the bandwidth of the transmission medium being overloaded. Because the failing element is in a failed condition its internal control system cannot be relied upon to perform this function and an alternative method is required.

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Page 1 of 6

Suppression of MPEG Transport Streams over

IP Outputs from a Standby Element in a Redundant System

Authors: John Sanders, Chang-An Hsiao, Guofei Wu

Abstract

MPEG transport streams are increasingly being carried over Ethernet rather than the traditional media such as ASI or DS-3. Unlike the traditional media Ethernet, especially at gigabit speeds, does not readily accommodate a simple change over switch to select the output of a redundant pair of transport stream sources (encoders, multiplexers, etc). Therefore when a back up element takes over from the primary following a failure provision must be made to suppress the output of the failed element to prevent contending transport streams being delivered to the destination element or the bandwidth of the transmission medium being overloaded. Because the failing element is in a failed condition its internal control system cannot be relied upon to perform this function and an alternative method is required.

We disclose a system where the back up element of the redundant pair directly commands the output interface of the failed element to suppress its output as soon as the failure is detected. The idea uses the Internet Control Message Protocol (ICMP) command "source quench" to signal to the failed element to stop transmitting. This is a network layer command so the Internet Protocol (IP) interface does not need to process higher layers to read it. The message will be sent by the backup element in the system when it detects a failure of the active element and prepares to take over from it. The meaning of the "source quench" message is modified for this application. Instead of temporarily reducing bitrate (as in its normal usage) the failed element's interface completely suppresses its output. Output is restored by a specific instruction from a controlling system when the failed element is repaired. The originating IP address of the "source quench" is checked by the failing element's interface to identify its companion and react as described in this disclosure. If the source is a third element then the failing element's interface will either ignore it or process it as defined in ICMP depending on whether full ICMP support is implemented. The backup unit will send the "source quench" command from its IP transport stream interface to the IP transport stream interface of the failing unit to by-pass any control modules that may have failed in the failed element. The message will pass through any IP switches or routers between the backup and the failed element. The backup element will send the message a number of times to ensure delivery. The backup element will not wait for acknowledgement because in the majority of failures the failed element will not be capable of sending an acknowledgement.

copyright Motorola, Inc. 2004

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1. References

Internet Control Message Protocol Network Working Group

Request for Comments: 792

2. Terms

TMX - Transcoder - Multiplexer, Motorola's general pur...