Netgear XCM8806 Chassis User Manual - Page 258

NETGEAR 8800 User Manual The network VLAN entry is used when traffic comes in from the network ports destined for an non-isolated port. Isolated Subscriber VLAN When a new MAC address is learned on an isolated subscriber VLAN port, two entries are added to the FDB table: • MAC address, isolated subscriber VLAN tag, port number, and a flag that indicates that the packet should be dropped • MAC address, network VLAN tag, port number, and a special flag for tag translation Ports in the isolated VLAN do not communicate with one another. If a port in the isolated VLAN sends a packet to another port in the same VLAN that already has an entry in the FDB, that packet is dropped. You can verify the drop packet status of an FDB entry by using the show fdb command. The D flag indicates that packets destined for the listed address are dropped. The network VLAN entry is used when traffic comes in from the network ports destined for an isolated port. Network VLAN When a new MAC address is learned on a network VLAN port, the following entry is added to the FDB table: MAC address, network VLAN tag, and port number. For every subscriber VLAN belonging to this PVLAN, the following entry is added to the FDB table: MAC address, subscriber VLAN tag, and port number Calculating the Total FDB Entries for a PVLAN The following formula can be used to estimate the maximum number of FDB entries for a PVLAN: FDBtotal = [(MACnon-iso + MACiso) * 2 + (MACnetwork * (VLANnon-iso + VLANiso + 1))] The formula components are as follows: • MACnon-iso = number of MAC addresses learned on all the non-isolated subscriber VLANs • MACiso = number of MAC addresses learned on all the isolated subscriber VLANs • MACnetwork = number of MAC addresses learned on the network VLAN • VLANnon-iso = number of non-isolated subscriber VLANs • VLANiso = number of isolated subscriber VLANs 258 | Chapter 9. VLANs