Information Technology Reference
In-Depth Information
main parameters of IP multicasting are:
•
The group membership is dynamic.
•
Hosts may join and leave the group at any time.
•
There is also no limit to the location or number of members in a host group.
•
A host may be a member of more than one group at a time.
•
A host group may be permanent or transient. Permanent groups are well-known and are
administratively assigned a permanent IP address. The group is then dynamically associ-
ated with this IP address. IP multicast addresses that are not reserved to permanent
groups are available for dynamic assignment to transient groups.
•
Multicast routers forward IP multicast datagrams into the Internet.
23.13.1 Group addresses
A special group of addresses are assigned to multicasting. These are known as Class D ad-
dresses, and they begin with 1110 as their starting 4 bits (Class E addresses with the upper
bits of 1111 are reserved for future uses). The Class D addresses thus range from
224.0.0.0
(11100000 00000000 00000000 00000000)
239.255.255.255
(11101111 11111111 11111111 11111111)
The address 224.0.0.0 is reserved. 224.0.0.1 is also assigned to the permanent group of all IP
hosts (including gateways), and is used to address all multicast hosts on the directly con-
nected network. Reserved and allocated addresses are:
224.0.0.0
Reserved
224.0.0.1
All systems on current subnet
224.0.0.2
All routers on current subnet
224.0.0.3
Unassigned
224.0.0.4
DVMRP routers
224.0.0.5
OSPFIGP all routers
224.0.0.6
OSPFIGP designated routers
224.0.0.7
ST routers
224.0.0.8
ST hosts
224.0.0.9
RIP2 routers
224.0.0.10-224.0.0.255
Unassigned
224.0.1.0
VMTP managers group
224.0.1.1
NTP network time protocol
224.0.1.2
SGI-dogfight
224.0.1.3
Rwhod
224.0.1.4
VNP
224.0.1.5
Artificial horizons-aviator
224.0.1.6
NSS-name service server
224.0.1.7
AUDIONEWS-audio news multicast
224.0.1.8
SUN NIS+ information service
224.0.1.9
MTP multicast transport protocol
224.0.1.10-224.0.1.255
Unassigned
224.0.2.1
rwho group (BSD) (unofficial)
224.0.2.2
SUN RPC PMAPPROC_CALLIT
224.0.3.0-224.0.3.255
RFE generic service
224.0.4.0-224.0.4.255
RFE individual conferences
