Netgear XCM8810 Chassis Hardware Installation Guide - Page 574

NETGEAR 8800 Chassis Switch CLI Manual limit-learning blackhole stop-learning lock-learning unlimited-learning unlock-learning Specifies a limit on the number of MAC addresses that can be dynamically learned on the specified ports. Specifies that blackhole entries are allowed. Specifies that the learning be halted to protect the switch from exhausting FDB resources by not creating blackhole entries. Specifies that the current FDB entries for the specified ports should be made permanent static, and no additional learning should be allowed. Specifies that there should not be a limit on MAC addresses that can be learned. Specifies that the port should be unlocked (allow unlimited, dynamic learning). Default Unlimited, unlocked learning. Usage Guidelines N/A Limited learning The limited learning feature allows you to limit the number of dynamically-learned MAC addresses per VLAN. When the learned limit is reached, all new source MAC addresses are blackholed at both the ingress and egress points. This prevent these MAC addresses from learning and responding to Internet control message protocol (ICMP) and address resolution protocol (ARP) packets. If the limit you configure is greater than the current number of learned entries, all the current learned entries are purged. Dynamically learned entries still get aged, and can be cleared. If entries are cleared or aged out after the learning limit has been reached, new entries will then be able to be learned until the limit is reached again. Permanent static and permanent dynamic entries can still be added and deleted using the create fdbentry and delete fdbentry commands. These override any dynamically learned entries. For ports that have a learning limit in place, the following traffic still flows to the port: • Packets destined for permanent MACs and other non-blackholed MACs • Broadcast traffic Traffic from the permanent MAC and any other non-blackholed MACs will still flow from the virtual port. 574 | Chapter 15. Security Commands