GMRP learning Summary

GMRP learning summary GMRP (GARP Multicast Registration Protocol) is a specific application of the GARP Protocol, defined in 802.1D, used for the switch and end station) automatically join (Register) or exit (deregister) a multicast group, so that the LAN knows where the multicast receiver is in the network, so that the multicast tree is a subset of the spanning tree, because the path to the switch and the endpoint device that are not added to the multicast group is trimmed (prune. GMRP is the multicast group registration and cancellation message, and the protocol that spreads to all switches and endpoints in the LAN. GMRP protocol is an optional feature of LAN devices. GMRP defines two property types only when Extended Filtering Servic is supported: 1) the vswitch and the endpoint device use the multicast member Information to declare that they are added to a multicast Group. The attribute value is the declared multicast address, the port that receives the multicast member information and registers the gmrp pdu writes the multicast address and the received port number to the filter Database (Filtering Database, which is the mac table we usually call) A Group registry Entry is created. Unlike a vswitch, the endpoint device must register the multicast registry entry only when source pruning is required. In this case, the endpoint device interface must support registration and application functions, it not only supports the application-only or simple application function. The source pruning function is described later. 2) The Group Service Requirement Information method and process are the same as those for registering and canceling multicast members. There are only two attribute values: Forward All Groups and Forward Unregistered Groups. That is, the switch or the endpoint device declares that it receives all multicast group data or not registered multicast group data. In this way, it can be compatible with switches that do not support the GMRP protocol (only switches that support basic Filtering Service). All multicast data or unregistered multicast data will be sent to him. Some endpoint devices (such as routers or network monitors) can use this feature to implement some special functions. The registration and cancellation of GMRP Group Membership and Group Service Requirement and the propagation in the LAN are defined by GARP, but the attribute values are embodied. By receiving GMRP protocol information, the source pruning endpoint device knows which multicast groups have multicast members in the LAN. If a multicast group does not have multicast members in the LAN, the endpoint device does not send data to this multicast group. This is the source pruning. Devices that support source pruning must support registration and application functions. Otherwise, the application-only or simple application functions are supported. (Vromrp interface, especially the receiver DR, is suitable for supporting this function) for GMRP Packet encapsulation formats, see GARP Message format. The special parameter values are as follows: GIP context = 0, indicates that GIP context is the base spanning tree (established by stp/rstp); GIP context = VID, indicating that GIP context is the MAC address of the vlan context packet: 0x0180c2000020 attribute type: attr type = 1: group Membership; attr type = 2: Group Service Requirement attribute value: the value of Group Membership is a 48-bit multicast mac address. The value of Group Service Requirement is a byte. 0 indicates Forward All Groups, 1 indicates Forward Unregistered Groups, 2 ~ 255 currently, the registration process and state machine of retained multicast are the same as those defined by GARP. However, after some control interfaces receive the registration declaration of a multicast group, if the multicast forwarding table does not have the corresponding table items of the multicast group and the input port. A new table item may be created, but it is subject to the following conditions: If the Restricted_Group_Registration control bit is true, the static Filtering Entry) in this multicast group, the value of Registrar Administrative Control must be Normal Registration to add and receive a logout declaration. If the group Filtering entry does not exist, ignore this declaration. If yes, the corresponding table items are deleted. If the multicast group does not receive the declared port but has no other port members, the multicast group is deregistered and spread to the LAN. GMRP in VLAN environment is in vlan-aware LAN, and multicast data streams are restricted in the spanning tree of vlan. GMRP receiving and propagation are limited to the spanning tree of the vlan and the member port range of the vlan. 1. If the input GMRP packet is un-tagged or priority-tagged, the packet is discarded if the accept Frame Type (Acceptable Frame Type) of the port is Admit Only VLAN taggedframes; otherwise, PVID is assigned to the GMRP packet. 2. If the input GMRP packet is tagged, GIP context is the VID in the packet. 3. If the input or output port is not a member port of the vlan, GMRP packets are discarded. 4. If the output port is un-tagged, GMRP does not contain tags. Otherwise