LevelOne GSW-4876 - Manual (Page 26)

C HAPTER 1 | Introduction
Description of Software Features
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be ignored and will not be written to the address table. Static addresses
can be used to provide network security by restricting access for a known
host to a specific port.
IEEE 802.1D B RIDGE
The switch supports IEEE 802.1D transparent bridging. The address table
facilitates data switching by learning addresses, and then filtering or
forwarding traffic based on this information. The address table supports up
to 16K addresses.
S TORE - AND -F ORWARD
S WITCHING
The switch copies each frame into its memory before forwarding them to
another port. This ensures that all frames are a standard Ethernet size and
have been verified for accuracy with the cyclic redundancy check (CRC).
This prevents bad frames from entering the network and wasting
bandwidth.
To avoid dropping frames on congested ports, the switch provides 8 MB for
frame buffering. This buffer can queue packets awaiting transmission on
congested networks.
S PANNING T REE
A LGORITHM
The switch supports these spanning tree protocols:
◆ Spanning Tree Protocol (STP, IEEE 802.1D) – Supported by using the
STP backward compatible mode provided by RSTP. STP provides loop
detection. When there are multiple physical paths between segments,
this protocol will choose a single path and disable all others to ensure
that only one route exists between any two stations on the network.
This prevents the creation of network loops. However, if the chosen
path should fail for any reason, an alternate path will be activated to
maintain the connection.
◆ Rapid Spanning Tree Protocol (RSTP, IEEE 802.1w) – This protocol
reduces the convergence time for network topology changes to about 3
to 5 seconds, compared to 30 seconds or more for the older IEEE
802.1D STP standard. It is intended as a complete replacement for STP,
but can still interoperate with switches running the older standard by
automatically reconfiguring ports to STP-compliant mode if they detect
STP protocol messages from attached devices.
◆ Multiple Spanning Tree Protocol (MSTP, IEEE 802.1s) – This protocol is
a direct extension of RSTP. It can provide an independent spanning tree
for different VLANs. It simplifies network management, provides for
even faster convergence than RSTP by limiting the size of each region,
and prevents VLAN members from being segmented from the rest of
the group (as sometimes occurs with IEEE 802.1D STP).