#readwise # Multicast Address - Wikipedia  ## Metadata - Author: [[wikipedia.org]] - Full Title: Multicast Address - Wikipedia - URL: https://en.wikipedia.org/wiki/Multicast_address ## Summary Multicast addresses are used for sending data to multiple recipients at once. The range 233.0.0.0/8 is for public multicast addresses. The range 239.0.0.0/8 is also used but is structured differently. In IPv6, multicast addresses start with the prefix ff00::/8. ## Highlights Ethernet frames with a value of 1 in the least-significant bit of the first octet of the destination [MAC address](https://en.wikipedia.org/wiki/MAC_address) are treated as multicast frames and are flooded to all points on the network. While frames with ones in all bits of the destination address (`FF-FF-FF-FF-FF-FF`) are sometimes referred to as [broadcasts](https://en.wikipedia.org/wiki/Broadcasting_(networking)), Ethernet generally does not distinguish between multicast and broadcast frames. Modern Ethernet controllers filter received packets to reduce CPU load, by looking up the hash of a multicast destination address in a table, initialized by software, which controls whether a multicast packet is dropped or fully received. The IEEE has allocated the address block `01-80-C2-00-00-00` to `01-80-C2-FF-FF-FF` for group addresses for use by standard protocols. Of these, the MAC group addresses in the range of `01-80-C2-00-00-00` to `01-80-C2-00-00-0F` are not forwarded by [802.1D](https://en.wikipedia.org/wiki/802.1D)-conformant [MAC bridges](https://en.wikipedia.org/wiki/MAC_bridge). ([View Highlight](https://read.readwise.io/read/01jnjwqxt7mpa3jsq9vfg8bcp4)) ^p34m5c ---