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Limiting the Number of MAC Addresses Learned from Each Logical Interface

You can configure a limit to the number of MAC addresses learned from the logical interfaces on an MX Series router.

To configure a limit to the total number of MAC addresses that can be learned from the logical interfaces, include the global-mac-limit limit statement at the [edit protocols l2-learning] hierarchy level:

The default limit to the number of MAC addresses that can be learned the router as a whole is 393,215. The range that you can configure for the router as a whole is 20 through 1,048,575.

After the configured MAC address limit is reached, the default is for packets to be forwarded. You can specify that the packets be dropped by including the packet-action drop statement at the [edit protocols l2-learning global-mac-limit] hierarchy level:

You can also configure a limit to the number of MAC address learned from all the interfaces in a bridge domain or from a specific logical interface only. .

Note:

The behavior is different for some configurations. For aggregated Ethernet interfaces and label-switched interfaces, the behavior is to learn all the new MAC addresses even when the limit has been reached. The excess addresses are later deleted. The learning limit does not apply to bridge domain trunk ports, because they have no counters for the individual domains, and those domains might have different MAC learning limits.

Note:

When static MAC addresses are configured, the learning limit is the configured limit minus the number of static addresses.

Note:

On MX Series routers running Junos OS Release 8.4 and later, statistics for an aged destination MAC entry are not retained. In addition, source and destination statistics are reset during a MAC move. In previous releases, only source statistics were reset during a MAC move.