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MONITORING INTERNET PROTOCOL (IP) TELEPHONY MEDIA LINKS

IP.com Disclosure Number: IPCOM000234993D
Publication Date: 2014-Feb-21
Document File: 3 page(s) / 100K

Publishing Venue

The IP.com Prior Art Database

Related People

Luc Bouchard: AUTHOR

Abstract

Techniques are presented herein for monitoring and reporting of Quality Of Service (QoS) markings of Internet Protocol (IP) media flows, such as voice, video, or other isochronous connections where QoS markings are used.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 52% of the total text.

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MONITORING INTERNET PROTOCOL (IP) TELEPHONY MEDIA LINKS

AUTHORS:

Luc Bouchard

CISCO SYSTEMS, INC.

ABSTRACT

    Techniques are presented herein for monitoring and reporting of Quality Of Service (QoS) markings of Internet Protocol (IP) media flows, such as voice, video, or other isochronous connections where QoS markings are used.

DETAILED DESCRIPTION

    Isochronous Internet Protocol (IP) media connections, such as voice telephony, video telephony and multimedia connections use OSI layer 3 (Network)-level markings end-to-end, to be interpreted by network nodes to provide a differentiated service to a flow, based on the markings. Examples of these markings include Type-of-Service (ToS) octet-borne IP Precedence, Differentiated Services Code Points (DSCP), and Per-Hop behavior (PHB). For voice communications, the media is marked with a PHB of Expedited Forwarding, a DSCP value of 46d or an IP Precedence of 5.

    Further, OSI layer 2 (Data)-level markings are used to impart Quality-of-Service (QoS) markings on frames within a network segment/broadcast domain. Examples of these marking include IEEE 802.1p Class-of-Service (CoS) markings. For voice communications, the media is marked with a CoS of 5.

    In a general sense, end nodes (such as telephones) generating flows traversing the network are responsible for imparting the appropriate L2 and L3 QoS markings to the frames/packets. In a fault-less, properly configured network, these frames/packets are forwarded with the QoS markings intact. These markings are then used by network nodes to identify and properly classify the frames/packets such that the appropriate queuing policies are applied to the flows. Upon delivery of these frames/packets to their ultimate destination, the related marking should typically remain as it was imparted at the origin of the flow.

Copyright 2013 Cisco Systems, Inc.
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    Faults, misconfiguration or policy conflicts can lead to the QoS markings to be changed, effectively defeating the network's ability to provide a differentiated service to so-called important flows. For example, if a voice media packet is marked as PHB EF at the source, and received with a marking of PHB Best Effort (BE), we know that a node somewhere in the network has changed the QoS marking, and that subsequent nodes in the network would not have been able to apply the proper queuing policy to the flow.

    Detecting such faults can be difficult, typically relying on the insertion of probes within the network, the injection of artificial "test" traffic into the network, or both. These measures are not pr...