Implementation of IGMP Snooping for the Linux Ethernet Bridge

Matevž Podnar (2010) Implementation of IGMP Snooping for the Linux Ethernet Bridge. EngD thesis.

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Abstract

The objective of this thesis was to implement IGMP Snooping for the Ethernet switch, based on Linux operating system. Implementation of the new functionality required modifications and improvements of different parts of the operating system: user space management software and parts of kernel. Algorithms and data structures, used for building multicast table, have been implemented in order to improve switching logic, which is now based on entries in the multicast table. Functionality tests and performance analyses of the upgraded switch represent the second part of the thesis. First part of tests and measurements was to set up a proper testing environment, which in all cases consisted of a switch with upgraded software and a different number of computers with a role to either generate or receive multicast traffic flow. Analyses has been made for two suits of cases: in the first suit only normal multicast traffic occured in the network. The second suit was a simulation of an attack where network was flooded with a large amount of different IGMP packets. Results showed that implementation of IGMP snooping in most cases brings positive effects on overall performance of software switches. Besides its main task, that is tolower network load, IGMP snooping in most cases also provides a method to reduce thenumber of switchings, which leads to lower load and higher through-put of a switch. Tests also proved suitability of the design and implementation: measurements showed that upgraded switch is more robust comparing to the original one even in the case of an attack with IGMP packets.

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