ZyXEL Communications GS1900 Series, Руководство пользователя

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GS1900 Series User’s Guide
82
C
HA PTER
1 0
Mo nito r: MAC Ta b le
10.1 O ve rvie w
This section provides information for
MAC Ta b le
in
Mo nito r
.
The
MAC Ta b le
screen (a MAC table is also known as a filtering database) shows how frames are
forwarded or filtered across the Switch’s ports. When a device (which may belong to a VLAN group)
sends a packet which is forwarded to a port on the Switch, the MAC address of the device is shown on
the Switch’s
MAC Ta b le
. It also shows whether the MAC address is dynamic (learned by the Switch) or
static (manually entered in the
Sta tic MAC Fo rwa rding
screen).
The Switch uses the
MAC Ta b le
to determine how to forward frames. See the following figure.
1
The Switch examines a received frame and learns the port from which this source MAC address came.
2
The Switch checks to see if the frame's destination MAC address matches a source MAC address
already learned in the
MAC Ta b le
.
• If the Switch has already learned the port for this MAC address, then it forwards the frame to that port.
• If the Switch has not already learned the port for this MAC address, then the frame is flooded to all
ports. Too much port flooding leads to network congestion.
• If the Switch has already learned the port for this MAC address, but the destination port is the same as
the port it came in on, then it filters the frame.
Fig ure 84
MAC Table Flowchart
This link takes you to a screen where you can view the MAC address and VLAN ID of a device attach to
a port. You can also view what kind of MAC address it is.