Since there is a shortage of ipv4 addresses, why can’t the D and E class, and further till 999 be opened?
That would make the number of ipv4 addresses currently available triple in number and help address the shortage perhaps.
In: 1
240.0.0.0/4 range (Class E) is often dropped in existing networking devices. If these addresses were assigned now, then only new software and gear without the restriction would be able to reach them.
224.0.0.0/4 (Class D) is for multicast like IP television to permit multiple viewers with only one data stream. Routers have special handling for those.
I don’t understand what you mean by the class going up to 999.
The 224.0.0.0/4 network (formerly class D) is used for multicast. This is when one server is sending a package to many different clients at once. Special configuration is needed for each router as the router have to send one incoming package into two or more directions. This feature have been neglected and can therefore not be assumed to work on the Internet. However it is used by a lot of ISPs who provide IPTV and is even supported by many video streaming services as long as the ISP have multicast support and a relay for the streaming service in their network.
So you can not use these addresses as they are already in use internally in many network. And network routers which are not set up with multicast often treat packages to these networks specially, for example by dropping the package.
The 240.0.0.0/4 network (formerly class E) used to be a broadcast network. The idea was to be able to send network packages to all Internet connected devices. This was a neat concept in the early days when the Internet was just a small research network. But as the Internet grew this did not scale well so it was removed. However a lot of routers are still configured to drop packages going to this network. So it is very hard to use these addresses.
Addresses with numbers above 255 is not possible. The IP address notation that we use is just a decimal representation of the binary addresses. Each of the four octets are eight bit long. And eight bit numbers go from 0 to 255.
As the IPv4 addresses were exhausted we did actually open a number of address ranges that were previously reserved for various reasons. But it turns out that they were reserved for a reason and users who were assigned these addresses often have issues with Internet connectivity from misconfiguration routers. The 240.0.0.0/4 would be even worse then these. And we have a perfectly reasonable solution to the IPv4 address exhaustion which is IPv6 so there is no need to assign any of the reserved address ranges.
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