Multicast Address; Table 18: Multicast Classes And Address Ranges - WAGO 852-1305 Manual

64 Enhanced Features
7.2.2.2

Multicast Address

A multicast address is associated with a group of interested receivers. According
to RFC 3171, addresses 224.0.0.0 to 239.255.255.255 (formerly Class D
addresses) are reserved as multicast addresses in IPv4.
The first octet (01) includes the broadcast/multicast bit. The lower 23 bits of the
28-bit multicast IP address are mapped to the 23 bits of the available ETHERNET
address space. This means that there is ambiguity in delivering packets. If two
hosts on the same subnet each subscribe to different multicast groups whose
addresses differ only in the first 5 bits, ETHERNET packets for both multicast
groups are sent to both hosts, requiring the network software in the hosts to
discard the unnecessary packets.

Table 18: Multicast Classes and Address Ranges

Class
Class A
Class B
Class C
Class D
Class E
Address Range
1.0.0.1 to
126.255.255.254
128.1.0.1 to
191.255.255.254
192.0.1.1 to
223.255.254.254
224.0.0.0 to
239.255.255.255
240.0.0.0 to
254.255.255.254
WAGO-ETHERNET-Zubehör 852
852-1305 8/4-Port 100BASE-T/1000BASE-SX/LX
Support
Supports 16 million hosts on each of 127
networks.
Supports 65,000 hosts on each of 16,000
networks.
Supports 254 hosts on each of 2 million
networks.
Reserved for multicast groups.
Reserved for future use or research and
development purposes.
Manual
1.1.0