Enterasys Networks 2200 - Manual (Page 272)

VLAN Configuration
12-10 VLAN Operation and Network Applications
12.7.2.2 Known Unicasts
When a VLAN switch receives a frame with a known MAC address as its destination address, the
action taken by the switch to determine how the frame is transmitted depends on the VLAN, the
VLAN associated FID, and if the port identified to send the frame is enabled to do so.
When a frame is received it is classified into a VLAN. The destination address is looked up in the
FID associated with the VLAN. If a match is found, it is forwarded out the port identified in the
lookup if, and only if, that port is allowed to transmit frames for that VLAN. If a match is not
found, then the frame is flooded out all ports that are allowed to transmit frames belonging to that
VLAN.
For example, assume that a frame is received by the switch depicted back in Figure 12-2 . This
frame is a unicast untagged frame received on Port 3. The frame is then classified for VLAN C.
The switch then makes its forwarding decision by comparing the destination MAC address to its
filtering database. In this case, the MAC address is looked up in the filtering database FID 3, which
is associated with VLAN C and VLAN D. The switch recognizes the destination MAC address of
the frame as being located out Port 4.
Having made the forwarding decision, the switch now examines the Port VLAN List of Port 4 to
determine if it may transmit a frame belonging to VLAN C. If so, the frame is transmitted out Port
4. If Port 4 has not been configured to transmit frames belonging to VLAN C, the frame is
discarded.
12.8 VLAN CONFIGURATION
This section describes how to set up the switch for local or remote management, and the VLAN
Local Management screens used to create and configure VLANs in a SmartSwitch.
12.8.1 Managing the Switch
The switch may be managed locally via a terminal connected to the COM port, or remotely
(SNMP or Telnet sessions) from a management station connected to a switch port that is a member
of the same VLAN as the switch’s Host Data Port. (By default, this is the default VLAN.) When
the switch is configured with VLANs, special precautions must be taken to use remote
management.