Mac Table - ZyXEL Communications GS3700 Series User Manual

This chapt er int roduces t he M AC Ta ble screen.
53.1 MAC Table Overview
The M AC Ta ble screen ( a MAC t able is also known as a filt ering dat abase) shows how fram es are
forwarded or filt ered across t he Swit ch's port s. When a device ( which m ay belong t o a VLAN group)
sends a packet which is forwarded t o a port on t he Swit ch, t he MAC address of t he device is shown
on t he Swit ch's M AC Ta ble . I t also shows whet her t he MAC address is dynam ic ( learned by t he
Swit ch) or st at ic ( m anually ent ered in t he St a t ic M AC For w a r ding screen) .
The Swit ch uses t he M AC Ta ble t o det erm ine how t o forward fram es. See t he following figure.
1 The Swit ch exam ines a received fram e and learns t he port from which t his source MAC address
cam e.
2 The Swit ch checks t o see if t he fram e's dest inat ion MAC address m at ches a source MAC address
already learned in t he M AC Ta ble .
• I f t he Swit ch has already learned t he port for t hi s MAC address, t hen it forwards t he fram e t o
t hat port .
• I f t he Swit ch has not already learned t he port for t his MAC address, t hen t he fram e is flooded t o
all port s. Too m uch port flooding leads t o net work congest ion t hen t he Swit ch sends an ARP t o
request t he MAC address. The Swit ch t hen learns t he port t hat replies wit h t he MAC address.
• I f t he Swit ch has already learned t he port for t h is MAC address, but t he dest inat ion port is t he
sam e as t he port it cam e in on, t hen it filt ers t he fram e.
Figure 376 MAC Table Flowchart
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MAC Table