A Novel Group Management Protocol for IP Multicast (LW-IGMPv3)

Abstract

With the deployment of multicast service, people gradually find that hardly any practical application uses Exclude filter mode to block sources. For this reason it is generally unnecessary to support the filtering function to block sources. In addition, the newly proposed SSM service model has defined several modifications to IGMPv3; therefore certain modifications to IGMPv3 must be performed before it can be deployed in the SSM model.

On the basis of the above analysis, LW-IGMPv3 is designed as a simplified version of IGMPv3 by Huawei Technology Co., which has been accepted by the IETF Mboned working group as a new draft. LW-IGMPv3 follows the query/response model adopted by all the previous IGMP versions. Therefore the network overhead of LW-IGMPv3 is basically the same with IGMPv3.

The major difference between IGMP and LW-IGMPv3 is below. First, the reception state for each attached network maintained by the multicast router is simplified as: (multicast address, group timer, (source records)); second, most record types have the same operation rule in both ASM and Include state, and only the TO_IN record type need to vary its operation according to the value of its group timer; third, the forwarding suggestion rule no longer needs to take the filter mode into consideration.

Functional research is performed, in which protocol states and message operation procedures are analyzed and compared to those of IGMPv3.

A simulation is conducted with our developed C++ simulator to generate network traffic and LW-IGMPv3 and IGMPv3 protocols deployed on the open source router platform XORP in order to compare router performance of LW-IGMPv3 and IGMPv3. During the simulation, the performance, which was measured by CPU processing time and Memory occupancy, of the device running LW-IGMPv3 is improved substantially compared to the one running IGMPv3 and the value of all the parameters of both IGMP protocol and multicast routing protocol are the same. Also, a simulation environment is established and a series of test cases is designed to verify the compatibility of LW-IGMPv3.

The result shows that LW-IGMPv3 is not only compatible with old versions of IGMP, but also shows great improvements in router performance and scalability.

This paper is supported by Huawei cooperation project, program for New Century Excellent Talents in Universities NCET-04-0115, Chinese national 863 Project (No. 2007AA01Z206 and No. 2006AA01Z235) and Chinese National 973 Project (No. 2003CB14806).