16
CONFIDENTIAL
26-Jan-04
© 2002 Procket Networks, Inc. All rights reserved.
Multicast Addressing
•IP Multicast Group Addresses
• 224.0.0.0–239.255.255.255
• Class “D” Address Space
• High order bits of 1st Octet = “1110”
•TTL value defines scope and limits distribution
•IP multicast packet must have TTL > interface TTL or it is discarded
•values are: 0=host, 1=network, 32=same site, 64=same region, 128=same continent, 255=unrestricted
•No longer recommended as a reliable scoping mechanism
IANA Reserved Addresses
   IANA is the responsible Authority for the assignment of reserved class D addresses.  Other interesting reserved addresses are:
    224.0.0.2   - PIMv1   (ALL-ROUTERS - due to transport in IGMPv1)
    224.0.0.5   - OSPF ALL ROUTERS      (RFC1583)
    224.0.0.6   - OSPF DESIGNATED ROUTERS    (RFC1583)
    224.0.0.9   - RIP2   Routers
    224.0.0.13 - PIMv2
    224.0.1.39 - CISCO-RP-ANNOUNCE     (Auto-RP)
    224.0.1.40 - CISCO-RP-DISCOVERY     (Auto-RP)

“ftp://ftp.isi.edu/in-notes/iana/assignments/multicast-addresses” is the authoritative source for reserved multicast addresses.


Additional Information
   "Administratively Scoped IP Multicast", June 1997, has a good discussion on scoped addresses.  This document is available at:

       “draft-ietf-mboned-admin-ip-space-03.txt”