3Com S7902E, Configuration Manual

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Dynamically Assigning Ports to VLANs Based on MAC Addresses
After a port on a device receives a packet with an unknown source MAC address, the device checks the
list of MAC address-to-VLAN mappings for a match. If a match is found, the device dynamically learns
the MAC address and assigns the receiving port to the corresponding VLAN. Then, subsequent packets
with this source MAC address can be directly forwarded through the port. This feature is referred to as
MAC-based dynamic port assignment. It allows different ports in a same VLAN to use the same MAC
address bundled with the VLAN.
The device periodically checks whether dynamic MAC address entries are updated. If a dynamic MAC
address entry is not updated within a certain period of time, the device deletes the MAC address entry,
thus removing the port included in the entry from the corresponding VLAN.
Do not enable this function together with 802.1X or MAC authentication. This is to allow ports to
dynamically join VLANs with no authentication performed.
Configuring a MAC Address-Based VLAN
z
MAC-based VLANs are available only on hybrid ports.
z
With MAC-based dynamic port assignment enabled, packets with unknown source MAC
addresses are sent to the CPU for processing. Because this packet processing mode has the
highest priority, the configuration of MAC learning limit and disabling MAC address learning
becomes invalid in this case. Therefore, you are recommended not to configure these two features
together with MAC-based dynamic port assignment.
z
In MAC-based dynamic port assignment, the port that receives a packet with an unknown source
MAC address can be successfully assigned to the matched VLAN only when the matched VLAN is
a static VLAN.
z
With MAC-based dynamic port assignment enabled, the port that receives a packet with no mask
MAC address.
z
Because MAC-based dynamic port assignment is mainly configured on the downlink ports of the
user access devices, do not enable this function together with link aggregation.
z
With MSTP enabled, if the MST instance for the corresponding VLAN is blocked, the packet with
the unknown source MAC address will fail to be sent to the CPU. As a result, the receiving port
cannot be dynamically assigned to the corresponding VLAN. Since MAC-based dynamic port
assignment is mainly configured on the access side, you are recommended not to configure it
together with MSTP.
Follow these steps to configure a MAC-based VLAN:
To do... Use the command... Remarks
Enter system view system-view —
Associate MAC addresses
with a VLAN
mac-vlan mac-address
mac-address [ mask mac-mask ]
vlan vlan-id [ priority priority ]
Required
Support for the mask keyword in
this command depends on the
device model.