Switch 7700 Configuration Guide

114 CHAPTER 6: MULTICAST PROTOCOL
Application of Multicast IP multicast technology effectively solves the problem of packet forwarding from
single-point to multi-point. It implements high-efficient data transmission from
single-point to multi-point in IP networks and can save a large amount of network
bandwidth and reduce network loads. New value-added services that use
multicast can be delivered including direct broadcasting, Web TV, distance
learning, distance medicine, net broadcasting station and real-time audio/video
conferencing.
■ Multimedia and streaming media applications
■ Communications of the training and corporate sites
■ Data repository and finance (stock) applications
■ Any “point-to-multi-point” data distribution
With the increase of multimedia services on IP networks, multicast has huge
market potential.
GMRP GMRP (GARP Multicast Registration Protocol), based on GARP, is used for
maintaining dynamic multicast registration information. All the switches
supporting GMRP can receive multicast registration information from other
switches and dynamically update local multicast registration information. Local
multicast registration information can be transmitted to other switches. This
information switching mechanism keeps consistency of multicast information
maintained by every GMRP-supporting device in the same switching network.
A host transmits GMRP Join message. After receiving the message, the switch
adds the port to the multicast group, and broadcasts the message throughout the
VLAN; thereby the multicast source in the VLAN knows the multicast member.
When the multicast source sends packets to its group, the switch only forwards
the packets to the ports connected to members, thereby implementing the Layer 2
multicast in VLAN.
The multicast information transmitted by GMRP includes local static multicast
registration information configured manually and the multicast registration
information dynamically registered by other switches.
ConfigurING GMRP The main tasks in a GMRP configuration include:
■ Enabling/Disabling GMRP
■ Enabling/Disabling GMRP on the port
In the configuration process, GMRP must be enabled globally before it is enabled
on the port.
Enable/Disable GMRP Globally
Perform the following configuration in system view.
Tab le 3 Enabling/Disabling GMRP Globally
Operation Command
Enable GMRP globally. gmrp
Disable GMRP globally. undo gmrp