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7. Configure multicast-group route
7.1 multicast-group route overview
the implement of D-Link's multicast-group route
♦ IGMP
♦ OLNK
♦ PIM-DM
♦ PIM-SM
♦ DVMRP
This chapter introduce how to configure multicast-group route protocol.If you want to know the
complete description of multicast-group route command of this chapter,please referrence
chapter about "multicast-group route command".
Traditional IP transmission allow one host to other one(unicast communication) or all(broadcast
communication), multicast-group technology provides the third choose,it allow a host send message to
some hosts.These hosts are called group member.
The
destination
(224.0.0.0—239.255.255.255). Transmission of multicast-group message is similar to UDP.It is a
best-effort service,and don't provide reliable transmission and error control which is provided by TCP.
The application which constitutes multicast-group needs sender and receiver.The sender need not join
a group to send a multicast-group message,and that the receiver must join a group before it receives
the message of this group.
The relation of the group member is dynamic,hosts could join and leave the group at any
moment,also,the position and number of group member are not limited.if you need,a host can be a
member of some groups at a time.So,the state of group and number of group member change as time
goes by.
Routers execute multicast-group route protocol(e.g.PIM-DM,PIM-SM)in order to maintenance the
route table which is used to transmit multicast-group message,and use IGMP protocol to learn the
states of the group member which connect to the same network.Hosts send IGMP report message in
order to join in the specified IGMP group.
IP multicast-group technology is fit to "one to many"multimedia implement.
7.1.1 The implement of D-Link's multicast-group
In the router software of D-Link, multicast-group route contain protocols as follow:
♦ IGMP run between router and host in the LAN,trace the relation of group member.
♦ OLNK is a static multicast-group technology used in simple topology structure,it not only implement
multicast-group transmit,but also reduce the waste of CPU and bandwidth of multicast-group route
protocol.
♦ PIM-DM/PIM-SM/DVMRP are dynamic multicast-group route protocol,run over the routers,they
establish multicast-group route table in order to implement multicast-group transmission.
The following picture display the multicast-group protocol used in the IP multicast-group environment.
Model Name
address
of
message
send
to
group
member
- 297 -
other
is
D
class
address
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