Advanced Routing

Abstract

Chapter 5 dealt with the IPv4 routing subsystem. This chapter continues with the routing subsystem and discusses advanced IPv4 routing topics such as Multicast Routing, Multipath Routing, Policy Routing, and more. This book deals with the Linux Kernel Networking implementation—it does not delve into the internals of userspace Multicast Routing daemons implementation, which are quite complex and beyond the scope of the book. I do, however, discuss to some extent the interaction between a userspace multicast routing daemon and the multicast layer in the kernel. I also briefly discuss the Internet Group Management Protocol (IGMP) protocol, which is the basis of multicast group membership management; adding and deleting multicast group members is done by the IGMP protocol. Some basic knowledge of IGMP is needed to understand the interaction between a multicast host and a multicast router.