H3C S3600 Series User Manual

Operation Manual – Multicast
H3C S3600 Series Ethernet Switches-Release 1510 Chapter 1 Multicast Overview
1-6
z Addressing mechanism: Information is sent from a multicast source to a group of
receivers through multicast addresses.
z Host registration: A receiving host joins and leaves a multicast group dynamically
to implement membership registration.
z Multicast routing: A router or switch establishes a packet distribution tree and
transports packets from a multicast source to receivers.
z Multicast application: A multicast source must support multicast applications, such
as video conferencing. The TCP/IP protocol suite must support the function of
sending and receiving multicast information.
1.2.1 Multicast Address
As receivers are multiple hosts in a multicast group, you should be concerned about the
following questions:
z What destination should the information source send the information to in the
multicast mode?
z How to select the destination address, that is, how does the information source
know who the user is?
These questions are about multicast addressing. To enable the communication
between the information source and members of a multicast group (a group of
information receivers), network-layer multicast addresses, namely, IP multicast
addresses must be provided. In addition, a technology must be available to map IP
multicast addresses to link-layer MAC multicast addresses. The following sections
describe these two types of multicast addresses:
I. IP multicast address
Internet Assigned Numbers Authority (IANA) categorizes IP addresses into five classes:
A, B, C, D, and E. Unicast packets use IP addresses of Class A, B, and C based on
network scales. Class D IP addresses are used as destination addresses of multicast
packets. Class D address must not appear in the IP address field of a source IP
address of IP packets. Class E IP addresses are reserved for future use.
In unicast data transport, a data packet is transported hop by hop from the source
address to the destination address. In an IP multicast environment, the destination
address of a packet is a multicast address identifying a mutlicast group.All the receivers
join a group. Once they join the group, the data sent to this group of addresses starts to
be transported to the receivers. All the members in this group can receive the data
packets. This group is a multicast group.
A multicast group has the following characteristics:
z The membership of a group is dynamic. A host can join and leave a multicast
group at any time.
z A multicast group can be either permanent or temporary.

H3C S3600 Series Specifications

General

Brand	H3C
Model	S3600 Series
Category	Switch
Language	English