In my last post, I discussed multicasts and some of the basic concepts. This time, I'm going to discuss technologies used by switches and routers to enable and configure multicasts. Specifically, I'm going to dive into addressing and IGMP. Understanding the details behind multicasts helps understand configuring multicasts as well as the issues limiting the use of multicasts on the web.
With the growth of IPTV and other IP media streaming technologies, applications for multicast technology are increasing. Live Video broadcasts and VoIP applications are viable uses for real time transmissions over an IP network from a single source to multiple recipients.
Most data transmissions are unicasts, which are a one-to-one data stream sent from one device to another device. Email, web surfing, and file downloads are all examples of unicasts, even for the busiest sites or most downloaded files. Although a single web page may be visited thousands of times each day, each time it is viewed it is individually transmitted to the requestor's PC as a unicast.
The first update to our Router Chart using new test techniques shows that some fast routers are even faster than we thought!