Gateway redundancy protocols

This paper covers how to increase the availability of data networks. Issue of high available services is very actual today. Redundancy is usually solved by the Spanning Tree Protocol on the 2nd layer of ISO/OSI model. This paper is dedicated to redundancy on 3rd layer of ISO/OSI model. The goal of paper is to explore possible solutions for the default gateway redundancy to increase availability of external networks. The survey is focused on FHRP (First Hop Redundancy Protocol) protocols, description of their functionality, network communication, and basic configuration. Next aim of the paper is comparison of these protocols and real time measurements of protocol performance. Outcome of the paper is functional description of HSRP, VRRP and GLBP protocols. Meaning of parameters in communication messages of HSRP and VRRP protocols is explained further. Paper contains basic configuration for every protocol with brief explanation of configuration commands. Measurements delay of choosing new active gateway has been performed on physical topology with physical devices. Latest version of FHRP was used during these measurements. The measured results indicate that performance of tested FHRP protocols is almost equivalent.