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DCS-3950 series Ethernet switch manual

8.4.1.1 show mac-address-table

Command: show mac-address-table [static|aging-time|blackhole|count] [address

<mac-addr>] [vlan <vlan-id>] [interface <interface-name>]

Parameter: static entry; aging-time address aging time; blackhole filtering entry; count

address counter; <mac-addr> entry’s MAC address; <vlan-id> entry’s VLAN number;

<interface-name> entry’s interface name

Command mode: Admin Mode

Default: MAC address table is not displayed by default.

Usage guide: This command can display various sorts of MAC address entries. Users

can also use show mac-address-table to display all the MAC address entries.

Example: Display all the filter MAC address entries.

Switch#show mac-address-table blackhole

8.4.2 Troubleshooting

Using the show mac-address-table command, a port is found to be failed to learn the

MAC of a device connected to it. Possible reasons:

z The connected cable is broken.

z Spanning Tree is enabled and the port is in ‘discarding’ status; or the device is just

connected to the port and Spanning Tree is still under calculation, wait until the

Spanning Tree calculation finishes, and the port will learn the MAC address.

z If not the problems mentioned above, please check for the switch port and contact

technical support for solution.

8.5 MAC Address Function Extension

8.5.1 MAC Address Binding

8.5.1.1 Introduction to MAC Address Binding

Most switches support MAC address learning, each port can dynamically learn

several MAC addresses, so that forwarding data streams between known MAC addresses

within the ports can be achieved. If a MAC address is aged, the packet destined for that

entry will be broadcasted. In other words, a MAC address learned in a port will be used for

forwarding in that port, if the connection is changed to another port, the switch will learn

the MAC address again to forward data in the new port.

However, in some cases, security or management policy may require MAC

addresses to be bound with the ports, only data stream from the binding MAC are allowed

to be forwarded in the ports. That is to say, after a MAC address is bound to a port, only

Digitalchina Networks DCS-3950 series User Manual

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