Openflow Path Fast Failover Fast Convergence Mechanism

Nor Masri Sahri,Koji Okamura

doi:10.7125/apan.38.4

Abstract

Whenever there is a link failure in the network, OpenFlow controller can react by computing a new backup path and provide the information to the affected node or the node can switch to backup path locally using the predefined backup path table provided by the OpenFlow controller. Setting predefined backup paths, results in a faster network rerouting time compared to backup path that establish on demand. However, it may lead to the use of sub-optimal backup path. In this paper, we present a fast and efficient failover mechanism for redirecting traffic flows to more optimal backup path when there is a link failure or congestion problem. We introduce a switch flow entry expiry mechanism to immediately reroute traffic to backup path to reduce the network restoration time. To update the switch with more optimal path information, the controller require a round trip to the network and this can introduce to slow network convergence. We proposed a local pre-calculated path dataset mechanism in Openflow controller to allow fast network convergence.

Highlights

To ensure application services are not interrupted during flight in the network, SDN must impose a mechanism to continue to forward traffic whenever there is a link or node failure
Whenever there is a link failure in the network, OpenFlow controller can react by computing a new backup path and provide the information to the affected node or the node can switch to backup path locally using the predefined backup path table provided by the OpenFlow controller
We proposed a local pre-calculated path dataset mechanism in Openflow controller to allow fast network convergence

Summary

Introduction

To ensure application services are not interrupted during flight in the network, SDN must impose a mechanism to continue to forward traffic whenever there is a link or node failure. In SDN, central controller does the computation of working path and the information is being push to the Openflow switch flow table and to achieve faster restoration, backup path can pre-computed in advance. We use optimization of traditional Djikstra algorithm to decide the path for traffic which has lower hop count and less congested path. We define the transmission delay as the time required by a node to put an entire packet into the communication media and it can be computed by the following equation: dtrans = L/R //where L is the length of a packet in bits and R is (3). By optimizing the Dijkstra algorithm, we aim to enable the Openflow controller to decide the best path for the traffic that has lower hop count and less congested path

Less Congested Path Fast Failover Network Model

Methodology

Future Work