Browse Prior Art Database

ASYMMETRICAL TWO INPUTS TRANSPORT LAYER FLOW CONTROL

IP.com Disclosure Number: IPCOM000008136D
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2002-May-21
Document File: 2 page(s) / 87K

Publishing Venue

Motorola

Related People

Rod Averbuch: AUTHOR [+3]

Abstract

Transport layer (layer 4) operation, such as TCP, is independent of layer 2 operation. Layer 4 flow control mechanism comes to resolve network congestion situation. As such, the mechanism assumes low error transport medium and low layer 2 activity if any (data layer delay).

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Technical Developments

ASYMMETRICAL TWO INPUTS TRANSPORT LAYER FLOW CONTROL

by Rod Averbuch, Israel Cimet and Valy Lev

INTRODUCTION

  Transport layer (layer 4) operation, such as TCP, is independent of layer 2 operation. Layer 4 flow control mechanism comes to resolve network congestion situation. As such, the mechanism assumes low error transport medium and low layer 2 activity if any (data layer delay).

  In a case of time out due to high layer 2 activity or packet loss, the transport layer activates its flow control mechanism, which is based on non linear window shrinking, in order to overcome wide net- work congestion.

  In Radio packet networks a data layer is applied on the payload data for error protection. There is no communication between the data layer and upper protocols such as TCP. Over the air layer 2 maintains a reasonable error protection, however layer 2 activity introduces high delay condition to the upper layers.

  If data traffic is busty and low in volume no special end to end flow control is necessary. Layer 2 buffer can temporary hold the extra data. However, in long session (land network extension) and high hand off rate (ESMR, PCS) situation data could accumulate and overflow. In order to avoid the overflow condition, which will cause data loss, some end to end flow control mechanism is needed. Leaving packet lost or time oat recovery to the transport layer will cause a tremendous degradation in data throughput due to:

1. Re-transmission of the all layer 3 packet instead of block in layer 2 recovery.

2. Fast TCP window shrinking flow control activa- tion and slow flow control recovery (TCP nature).

SOLUTION

  Long sessions and high handoff rate could ca...