Cisco Catalyst 2000 Configuration Handbook page 319

298 Cisco LAN Switching Configuration Handbook
00000001-00000000-010111110
First 24 bits of MAC address
01-00-5E
Translates into Layer 2 MAC address
Figure B-6 Layer 3-to-Layer 2 Multicast Translation
Well-known or assigned IP protocols are registered with the IANA. The information pre-
sented here is reproduced with permission from the IANA. For the most current IP proto-
col number assignment information, refer to www.iana.org/numbers.htm under the
"Multicast Addresses" link.
Host extensions for IP multicasting (RFC 1112) specifies the extensions required of a
host implementation of the Internet Protocol to support multicasting. The multicast
addresses are in the range 224.0.0.0 through 239.255.255.255. Current addresses are listed
in the table that follows.
The range of addresses between 224.0.0.0 and 224.0.0.255, inclusive, is reserved for the
use of routing protocols and other low-level topology discovery or maintenance proto-
cols, such as gateway discovery and group membership reporting. Multicast routers
should not forward any multicast datagram with destination addresses within this range,
regardless of its TTL.
Table B-4 shows the registered multicast addresses, along with the application, and the
RFC number (if applicable) or other reference.
Table B-4 Registered Multicast Addresses and Associated Applications, RFCs, and
Group, Application, and References
Base address (reserved)
RFC 1112
Multicast group address Layer 3
239.208.46.95
Bit is set to 0
0 1010000-00101110-010111111
Lower 23 bits of MAC address are the
same as the lower 23 bits of the
IP multicast address
50-2E-5F
References
1 1010000.00101110.01011111
Address
224.0.0.0