NETGEAR AV Line M4250 GSM4210PX 8-Port Gigabit PoE+ Compliant Managed AV Switch with SFP (220W) - Manual (Page 253)

Table 65. MFDB statistics information
Description Field
The maximum number of entries that the multicast forwarding database
table can hold.
Max MFDB Table Entries
The largest number of entries that were present in the multicast forwarding
database table since the last reset. This value is also known as the MFDB
high-water mark.
Most MFDB Entries Since Last
Reset
The current number of entries in the multicast forwarding database table. Current Entries
Internet Group Management Protocol
snooping
Internet Group Management Protocol (IGMP) snooping allows a switch to forward
multicast traffic intelligently. Multicast IP traffic is destined to a host group. Host groups
are identified by class D IP addresses, which range from 224.0.0.0 to 239.255.255.255.
Based on the IGMP query and report messages, the switch forwards traffic only to the
ports that request the multicast traffic. This prevents the switch from broadcasting the
traffic to all ports and possibly affecting network performance.
A traditional Ethernet network can be separated into different network segments to
prevent placing too many devices onto the same shared media. Bridges and switches
connect these segments. When a packet with a broadcast or multicast destination
address is received, the switch forwards a copy into each of the remaining network
segments in accordance with the IEEE MAC Bridge standard. Eventually, the packet is
made accessible to all nodes connected to the network.
This approach works well for broadcast packets that are intended to be seen or
processed by all connected nodes. In the case of multicast packets, however, this
approach could lead to less efficient use of network bandwidth, particularly when the
packet is intended for only a small number of nodes. Packets are flooded into network
segments where no node is receptive to the packet. While nodes rarely incur any
processing overhead to filter packets addressed to unrequested group addresses, they
cannot transmit new packets onto the shared media during the period that the multicast
packet is flooded. The problem of wasting bandwidth is even worse when the LAN
segment is not shared, for example in full-duplex links.
Main User Manual 253 Configure Switching Information
AV Line of Fully Managed Switches M4250 Series Main User Manual