#7) IPv6 provides better Multicast and Anycast
abilities compared to IPv4

In a multicast technique a packet is copied from one stage down to another in a hierarchical tree-like structure, instead of sending it from the source directly. This means that there are fewer packets in the network thereby optimizing bandwidth utilization and also reducing the resources required at each network node. This multicast technique is particularly useful when streams of information have to be made available to a wide variety of connected devices and not just one single destination. For example multicast technique is used to relay audio data, video data, news feeds, financial data feeds and so on.

multicast technique diagram

[Source: Cisco]

Challenge to IPv4

internet routerThe biggest problem with IPv4 multicast is that it is possible only on subnets and most Internet routers are not configured to support IPv4 multicast. For effective use of multimedia applications it should be possible to address different hosts, which belong in different subnets.



How does IPv6 provide a solution?

IPv6 extends the multicasting capabilities of IPv4 by offering a large multicast address range. Obviously, this limits the degree to which the information packets have now to be propagated and significantly improves the network efficiency.

IPv6 also improves dramatically on the concept of anycast services, which is available, though in a very minimal form in IPv4. In anycast services, packets are not sent to all the nodes in the network but only to the nearest reachable member. A typical application where anycast would be of tremendous use is say, while discovering a server of a given type e.g. a DNS server, among a group of servers. It will also provide redundant paths to other servers so that if for some reason, the route to the primary server becomes unavailable, in the next session, a connection will be provided to the next server in the group.

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