Mapping Ip Mac Multicast Addresses - Hirschmann MACH 4000 User Manual

Multicast Routing

9.1.3 Mapping IP MAC Multicast Addresses

When IP data packets are sent via Ethernet, the IP address is assigned to
a MAC address, and therefore IP Multicast addresses are also mapped
onto MAC Multicast addresses.
The 23 lower-value bits of the 32-bit IP Multicast address make up the
23 lower-value bits of the 48-bit MAC Multicast address.
Of the remaining 9 bits of the IP Multicast address, 4 bits are used as the
class D identification for the Multicast address.
The remaining 5 bits ensure that 32 IP Multicast addresses can be mapped
onto one and the same MAC Multicast address.
0 = Internet Multicast
1= reserviert
IEEE 802.3 Multicast-MAC-Address
0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0
0 1 0
48-bit Multicast MAC Address 01:00:5E:40:70:9F
Figure 33: Conversion of the IP address to the MAC address
100
32-bit Multicast IP Address
239.192.112.159
239 192
1 1 1 0 1 1 1 1 1 1 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 1 1 1 1
Class D ignored
0 1 0 1 1 1 1 0 0 1 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 1 1 1 1
0 5 E 4
9.1 Multicast Addresses
112 159
0 7 0 9 F
Routing L3P
Release 4.0 11/07