Netgear XCM8806 Chassis Hardware Installation Guide - Page 457

NETGEAR 8800 Chassis Switch CLI Manual blackhole Enables the blackhole option. Any packets with either a source MAC address or a destination MAC address matching the FDB entry are dropped. Default N/A. Usage Guidelines Permanent entries are retained in the database if the switch is reset or a power off/on cycle occurs. A permanent static entry can either be a unicast or multicast MAC address. After they have been created, permanent static entries stay the same as when they were created. If the same MAC address and VLAN is encountered on another virtual port that is not included in the permanent MAC entry, it is handled as a blackhole entry. The static entry is not updated when any of the following take place: • A VLAN identifier (VLANid) is changed. • A port is disabled. • A port enters blocking state. • A port goes down (link down). A permanent static FDB entry is deleted when any of the following take place: • A VLAN is deleted. • A port mode is changed (tagged/untagged). • A port is deleted from a VLAN. Permanent static entries are designated by spm in the flags field of the show fdb output. You can use the show fdb command to display permanent FDB entries. If the static entry is for a PVLAN VLAN that requires more than one underlying entry, the system automatically adds the required entries. For example, if the static entry is for a PVLAN network VLAN, the system automatically adds all required extra entries for the subscriber VLANs. You can create FDB entries to multicast MAC addresses and list one or more ports. If more than one port number is associated with a permanent MAC entry, packets are multicast to the multiple destinations. IGMP snooping rules take precedence over static multicast MAC addresses in the IP multicast range (01:00:5e:xx:xx:xx) unless IGMP snooping is disabled. Note: When a multiport list is assigned to a unicast MAC address, load sharing is not supported on the ports in the multiport list. Chapter 10. FDB Commands | 457