iES28TG/iES28GF User Manual
34
iS5 Communications Inc.
Label
Description
Protocol Version
The version of the STP protocol. Valid values include STP, RSTP and
MSTP.
Forward Delay
The delay used by STP bridges to transit root and designated ports
to forwarding (used in STP compatible mode). The range of valid values is
4 to 30 seconds.
Max Age
The maximum time the information transmitted by the root bridge is
considered valid. The range of valid values is 6 to 40 seconds, and
Max
Age
must be <= (FwdDelay-1)*2.
Maximum Hop Count
This defines the initial value of remaining hops for MSTI information
generated at the boundary of an MSTI region. It defines how many
bridges a root bridge can distribute its BPDU information to. The
range of valid values is 4 to 30 seconds, and
MaxAge must be <= (FwdDelay-1)*2.
Transmit Hold Count
The number of BPDUs a bridge port can send per second. When
exceeded, transmission of the next BPDU will be delayed. The range
of valid values is 1 to 10 BPDUs per second.
Save
Click to save changes.
Reset
Click to undo any changes made locally and revert to previously saved
values.
4.3.2
MSTP
MSTP was developed to improve recovery times since STP and RSTP takes seconds, which is n ot
acceptable in some industrial applications. MSTP supports multiple spanning trees within a
network by grouping and mapping multiple VLAN’s into different spanning-tree instances, known as
MSTI’s, forming individual MST regions. Each switch is assigned an MST region. Each MST region
consists of one or more MSTP switches with the same VLAN’s, at least one MST instance, and the
same MST region name. This allows the switches to use different paths in the network to effectively
balance loads.
Port Settings
This page allows you to examine and change the configurations of current MSTI ports. A MSTI port is a
virtual port, which is instantiated separately for each active CIST (physical) port for each MSTI
instance configured and applicable for the port. The MSTI instance must be selected before
MSTI port configuration options are displayed.
