Netgear XSM4324FS Software Administration Manual Software Version 12.x - Page 436

M4300 Series and M4300-96X Fully Managed Switches while port loop protection is enabled. If the switch receives a packet with the previously mentioned multicast destination address, the source MAC address in the packet is compared with the MAC address of the switch. If the MAC address does not match, the packet is forwarded to all ports that are members of the same VLAN, just like any other multicast packet. The packet is not forwarded to the port from which it was received. If the source MAC address matches the MAC address of the switch, the switch can perform one of the following actions, depending on how you configure the action: • The port is shut down. • A log message is generated. (If a syslog server is configured, the log message can be sent to the syslog server.) • The port is shut down and a log message is generated. If loop protection is disabled, the multicast packet is silently dropped. You can configure the interval between two successive loop protection PDU packets with the transmit-interval command. The default interval parameter is 5 seconds. If the switch receives a loop protocol packet on a port for which the action is set to shut down the port, the port can no longer receive and send frames. Loop protection operates at the port level, regardless of VLAN assignment and membership, detecting loops across VLANs. The protection uses the OUI-Extended Ethernet Type frame format (0x88b7), which is an IEEE-sanctioned format for vendor-specific packets. Loop protection does not impact end nodes and is not intended for ports that serve as uplinks between spanning tree-aware switches. Loop protection can coexist with Spanning Tree Protocol (STP). You can enable both loop protection and STP on a port because these features function independently of each other. STP does not bring a port down when a loop is detected but keeps the port in blocking state. Because PDUs are allowed in a blocking state, loop protection packets are received and loop protection brings down the port that is involved in the loop (if the configured action is to shut down the port). The following example shows how you can enable loop protection on ports 1/0/1 and 1/0/2: 1. Enable loop protection globally. (Netgear Switch) (Config) #keepalive Enable loop protection on ports 1/0/1 and 1/0/2 and set the violation action to shutting down the port and logging a message. (Netgear Switch) (Config)#interface 1/0/1,1/0/2 (Netgear Switch) (Interface 1/0/1-1/0/2)#keepalive (Netgear Switch) (Interface 1/0/1-1/0/2)#keepalive action both Tools 436 Software Administration Manual