After previously exploring the basics of UDP broadcasting, why IPv4 subnets are an exciting feature that you really want to dive into, as well as the contentious topic of IPv6, there are still plenty of elephants to admire and cans of sardines to crack open. One of them being the topic of broadcasting versus multicasting, which at first glance sounds rather similar and may even have some wondering why you’d even bother with multicasting if you can just send-and-forget with IPv4 broadcast address.
Of course, we already found out that IPv4 broadcast addresses come in a few flavors, and that’s before you start even considering the implications of subnets and routing limits. When we then consider that in IPv6 broadcast addresses were dropped completely in favor of link-local multicast addresses, and that IPv4 also supports multicast, then this raises the question whether using IPv4 multicast’s own take on ‘link-local’ doesn’t make more sense.
Or perhaps more succinctly put, is IPv4’s take on link-local broadcasting as straightforward as IPv6’s?
Before diving into multicasting, there is one important topic that has been absent from the IPv4 discussions so far. This being that of
The classful network legacy of IPv4.
The most obvious implication of CIDR is that it is the reason why we write IPv4 addresses the way that we do today, yet the classes from
If we now look at the IPv4
