CGMP agreement, Cisco Group Management Protocol:
CGMP for multicast traffic at Layer 2 network restrictions. Since the switch can not view the three packets, IGMP packets can not be distinguished. Use the CGMP, tell the switch router multicast group user interface, only router capable of producing CGMP packet, the switch just listening CGMP packets.
Mainly provide some services:
1, to allow IP multicast packets to be switched to those ports that have IP multicast clients.
2, the network bandwidth is saved in the user field to warrant broadcast unwanted IP multicast traffic.
3, no additional overhead when creating a separate VLAN for each multicast packet switched network.
There are two CGMP packets:
the Join router to join a multicast group members to switch to advertise
Leave a router deleted from the multicast group members to switch Notices
Once activated CGMP is used, it can automatically identify CGMP-Capable router connected port. CGMP is activated by default mode, it supports the largest registered as IP multicast group 64. CGMP support multicast routers periodically send CGMP was added with information (JoinMessages), performs network switching to advertise their behavior. Receiving switch save the information, and sets a retention time similar to the router (the Holdtime) timer (Timer). Each switch receives a CGMP join message, timer also with its constantly updated. When the router hold time is terminated, the switch will be responsible for all known multicast group out of CGMP.
RGMP protocol, the Cisco router port Group Management Protocol
Cisco router port Group Management Protocol (RGMP) make up the Internet Group Management Protocol (IGMP: Internet Group ManagementProtocol) deficiencies in Snooping technology mechanism exists. RGMP protocol acting between the multicast routers and switches. By RGMP, the switch may be forwarded multicast packet is fixed routers need thereof. RGMP is designed for backbone switching is applied to a network (BackboneSwitched Networks) connected to multiple routers.
IGMP Snooping technique limitations mainly in: this technique can only be fixed directly or indirectly to multicast traffic through the other switches connected between the receiver switch port, at IGMP Snooping technique, multicast traffic can not be fixed at least one port connected to the multicast router, the multicast traffic to cause diffusion of these ports. IGMP Snooping is inherent in the mechanism of limitations. Based on this, the router can not report flow state, so the switch can only know the type of multicast traffic requested by the host, without knowing the type of router traffic received by the port.
RGMP protocol support multicast traffic in fixed-port router. Fixed flow for the efficient implementation requirements of network switches and routers must support RGMP. By an RGMP, key switches for each port need to know the type of the group, and then transmits the information to the multicast router switch. But only RGMP router sends information at the expense of RGMP messages received. When the group is no longer required to receive traffic, the router will send a leave message RGMP (Leave Message). RGMP protocol network switches consumes RGMP messages reach network ports and subjected to processing operations. Moreover, the switch does not allow RGMP the received information is forwarded RGMP / spread to other network ports.
RGMP is designed to support distribution tree with Join / Prune multicast routing protocol used in combination. Typical protocol PIM-SM. RGMP protocol specifies only IP v4 multicast routing operation, without including IPv6.
