Mac Bridge Function - Fujitsu PRIMEQUEST 480 System Design Manual

CHAPTER 5 Business LAN Management by GSWB
5.2.2

MAC bridge function

A GSWB supports the MAC bridge function complying with IEEE802.1D.
The MAC bridge function relays frames between MAC sublayers in transmission
lines that differ up to Media Access Control (MAC). The MAC layer is a lower
sublayer of the data link layer. The following functions are also supported as related
functions.
Address learning function
The function for learning MAC addresses is supported. This function
automatically learns, for filtering and forwarding execution purposes, which bridge
port each terminal is connected to. A learning table stores the correspondence of
MAC addresses and ports.
Age-out function
The information on MAC addresses and ports registered in a learning table is
deleted if the information is not referenced for a certain amount of time. This
function allows more effective use of the learning table. The user can set the aging
time.
Figure 5.2
Address learning Address learning
Self-learning with
Self-learning with
communication on
communication on
a LAN
a LAN
MAC address
a
e
c
Adding Adding
5-12
shows why this function is effective.
If, however, there is no communication If, however, there is no communication
for a certain amount of time, information for a certain amount of time, information
is deleted. is deleted.
PRIMEQUEST PRIMEQUEST
Port number
1
Partition#n Partition#n
5
2
GSWB GSWB
1 1 2 2
a b c d
MAC address
Figure 5.2 Address learning and age-out
When a terminal is moved, if learned information is not When a terminal is moved, if learned information is not
deleted, it may not be possible to execute deleted, it may not be possible to execute
communication at the move-to location. communication at the move-to location.
Age-out Age-out
Because Because
Port
5 5
number
To the To the
previous port previous port
e
a
PRIMEQUEST PRIMEQUEST
Partition#n Partition#n
GSWB GSWB
Port
1 1 2 2 5 5
number
Packets are Packets are
not reached. not reached.
?
b d e
Moving Moving
C122-B001-02EN
c