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XG2000 series User's Guide
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All Rights Reserved, Copyright (C) PFU LIMITED 2009
4.1 Basic Switch Functions
This section describes the basic switch functions.
4.1.1 Switching Mode
The device provides the following two switching modes.
z Store-and-forward switching mode
After the device finishes receiving a frame, it checks the FCS (Frame Check Sequence) and
performs a validity check (on packet size, etc.) before forwarding the frame. If the switch
receives a frame with an error frame, it discards it.
z Cut-through switching mode
The device transmits the frame to the destination as soon as the first 64 bytes of the frame
are received with no errors. Since the device starts transmitting the frame before it receives
the entire frame, this mode allows forwarding at low latency.
To change the switching modes, carry out the following procedures in the administrator EXEC mode.
Command Task
xg# configure terminal
Switch to global configuration mode.
xg(config)# bridge forward-mode
{cut-through | store-and-forward }
xg(config)# no bridge forward-mode
Select the cut-through (or store-and-forward) for the
switching mode.
xg(config)# exit
Exit to administrator EXEC mode.
4.1.2 MAC Address Table Management
The MAC address table is a database used for managing the association between address information and destination ports.
The device can learn up to 16384 entries of MAC addresses.
z MAC address table management
The device has two methods for MAC address table management.
− SVL(Shared VLAN Learning)
The device learns MAC addresses common to all VLANs. Different VLANs with identical
MAC addresses are treated as identical entries.
− IVL(Independent VLAN Learning)
The device learns MAC addresses separately for each VLAN. Identical MAC addresses with
different VLANs are treated as separate entries.
To change the MAC address table management modes, carry out the following procedures in the
management EXEC mode.
Command Task
xg# configure terminal
Switch to the global configuration mode.
xg(config)# bridge learn-mode { ivl | svl }
xg(config)# no bridge learn-mode
Select IVL or SVL for the MAC address table management
mode.
xg(config)# exit
Exit to administrator EXEC mode.
xg# copy running-config startup-config
Save the current settings of the device to nonvolatile memory.
xg# reset
If the MAC address table management mode is changed, the
new setting becomes enabled after the device is restarted.
z Dynamic MAC address learning
The device dynamically learns MAC addresses from received frames. If MAC addresses are not
refreshed before the aging time expires, they will be removed from the MAC address table.
To disable the dynamic learning, carry out the following procedures in the administrator
EXEC mode.
Command Task
xg# configure terminal
Switch to global configuration mode.
xg(config)# interface port 1 2 3
xg(config)# interface port range 1 3
Switch to the interface edit mode to specify the port(s) to be
configured.
In this example, the global interface configuration mode is
selected for ports 1 through 3.
xg(config-if)# suppress-address-learning
xg(config-if)# no
suppress-address-learning
Enable (or disable) the dynamic MAC address learning.
xg(config-if)# exit
Exit to global configuration mode.
xg(config)# exit
Exit to administrator EXEC mode.