Browse Prior Art Database

Method to prevent unnecessary transmission of packets from a local mobility agent to a mobile node

IP.com Disclosure Number: IPCOM000007189D
Original Publication Date: 2002-Mar-04
Included in the Prior Art Database: 2002-Mar-04
Document File: 2 page(s) / 22K

Publishing Venue

Motorola

Related People

Narayanan Venkitaraman: AUTHOR

Related Documents

IETF Internet Draft: OTHER [+3]

Abstract

A local mobility agent is a node that enhances handoff performance of by buffering packets and re-transmitting them when a mobile node does a handoff. When retransmission occurs, packets that the mobile node has already received successfully may be transmitted again, resulting in wastage of resources and increased packet delays. In this document we introduce IP sequence number to solve this problem. We also discuss the issues with using sequence numbers that are present in other layers.

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Method to prevent unnecessary transmission of packets from a local mobility agent to a mobile node

 

Narayanan Venkitaraman

 

Abstract

A local mobility agent is a node that enhances handoff performance of by buffering packets and re-transmitting them when a mobile node does a handoff.  When retransmission occurs, packets that the mobile node has already received successfully may be transmitted again, resulting in wastage of resources and increased packet delays. In this document we introduce IP sequence number to solve this problem. We also discuss the issues with using sequence numbers that are present in other layers.

Introduction

Mobile hosts connecting to a network change their point of access into the network as users move across different access points and sub-nets.  During handoff, the mobile node may observe packet losses due to the delay in establishing link layer and network layer connectivity. A local mobility agent (LMA) is an anchor point [1] that makes the handoff smooth by buffering packets and then re-transmitting the buffered packets on a receiving a request, typically after a handoff, from the mobile node. As the handoff delay is variable, the size of the LMA buffer must be large enough to prevent any possible packet loss. However, if the buffer is large, then there will be unnecessary retransmission of packets, which will result in delays and wasted resources. This document describes a method for addressing this problem effectively.

Related Work

Sequence numbers have traditionally been by other layers (especially link layer and transport layer) to identify packet losses and enable retransmission of lost packets. Link layer sequence numbers cannot be used to prevent retransmission when we handoff from one access router to another. This is because the sequence numbering exists in link layer between the access point and the mobile node. But there is no communication between access points as we handoff from one sub-net to another. Using the sequence numbers of higher layers is...