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Apparatus and Method for Adjusting Peak Cell Rates

IP.com Disclosure Number: IPCOM000125360D
Original Publication Date: 2005-Jun-20
Included in the Prior Art Database: 2005-Jun-20
Document File: 1 page(s) / 21K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

Traditionally, in networks, the Peak Cell Rate (PCR) assumes a stable bandwidth. In DSL networks however it is yet normal that the bandwidth changes (e.g. from 128000 bps to 64000 bps) known or unknown to the user. In networks with more than one VC (Virtual Circuit) this can result in "VC-flapping". In the following example a DSL network with three VCs is shown that works properly on 128000 bps (301 cells per second (cps)) VC1 : PCR=225 (equates to 95400 bps) VC2 : PCR=60 (equates to 25440 bps) VC3 : PCR=15 (equates to 6360 bps) => 225 + 60 + 15 = 300 (approx. 128 kbps) If now the line rate changes from 128000 bps to 64000 bps with this initial configuration, VC1 demands 95400 bps. That is 31400bps more that currently available. VC2 and VC3 will not have enough bandwidth to work properly. That is called "VC-flapping".

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Apparatus and Method for Adjusting Peak Cell Rates

Idea: Mark Estrage, US-Dallas, Texas

Traditionally, in networks, the Peak Cell Rate (PCR) assumes a stable bandwidth. In DSL networks however it is yet normal that the bandwidth changes (e.g. from 128000 bps to 64000 bps) known or unknown to the user. In networks with more than one VC (Virtual Circuit) this can result in "VC- flapping". In the following example a DSL network with three VCs is shown that works properly on 128000 bps (301 cells per second (cps))

VC1 : PCR=225 (equates to 95400 bps) VC2 : PCR=60 (equates to 25440 bps) VC3 : PCR=15 (equates to 6360 bps) => 225 + 60 + 15 = 300 (approx. 128 kbps)

If now the line rate changes from 128000 bps to 64000 bps with this initial configuration, VC1 demands 95400 bps. That is 31400bps more that currently available. VC2 and VC3 will not have enough bandwidth to work properly. That is called "VC-flapping".

By representing PCR as a percentage with a maximum value being 100 to all user interfaces, the User can more effectively and accurately define their own traffic shaping as a function of percent available bandwidth and thus avoiding the rigorous math involved in PCR recalculations upon each line rate change. PCP could automatically be recalculated upon each line rate change thus allowing all VCs a more equal chance to communicate yet still maintaining some similance of bandwidth management and prioritization even if the bandwidth changes. This Idea is explicate...