LevelOne GSW-4876 - Manual (Page 135)

C HAPTER 4 | Configuring the Switch
Configuring the Spanning Tree Algorithm
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C ONFIGURING
STP/RSTP/CIST
I NTERFACES
Use the CIST Ports Configuration page to configure STA attributes for
interfaces when the spanning tree mode is set to STP or RSTP, or for
interfaces in the CIST. STA interface attributes include path cost, port
priority, edge port (for fast forwarding), automatic detection of an edge
port, and point-to-point link type.
You may use a different priority or path cost for ports of the same media
type to indicate the preferred path, edge port to indicate if the attached
device can support fast forwarding, or link type to indicate a point-to-point
connection or shared-media connection. (References to “ports” in this
section means “interfaces,” which includes both ports and trunks.)
P ATH
Basic/Advanced Configuration, Spanning Tree, CIST Ports
P ARAMETERS
These parameters are displayed:
◆ Port – Port identifier.
This field is not applicable to static trunks or dynamic trunks created
through LACP. Also, note that only one set of interface configuration
settings can be applied to all trunks.
◆ STP Enabled – Sets the interface to enable STA, disable STA, or
disable STA with BPDU transparency. (Default: Enabled)
BPDU transparency is commonly used to support BPDU tunneling,
passing BPDUs across a service provider’s network without any
changes, thereby combining remote network segments into a single
spanning tree. As implemented on this switch, BPDU transparency
allows a port which is not participating in the spanning tree (such as an
uplink port to the service provider’s network) to forward BPDU packets
to other ports instead of discarding these packets or attempting to
process them.
◆ Path Cost – This parameter is used by the STA to determine the best
path between devices. Therefore, lower values should be assigned to
ports attached to faster media, and higher values assigned to ports
with slower media. (Path cost takes precedence over port priority.)
By default, the system automatically detects the speed and duplex
mode used on each port, and configures the path cost according to the
values shown below.
Table 9: Recommended STA Path Cost Range
Port Type IEEE 802.1D-1998 IEEE 802.1w-2001
Ethernet 50-600 200,000-20,000,000
Fast Ethernet 10-60 20,000-2,000,000
Gigabit Ethernet 3-10 2,000-200,000