3Com 400 Family Configuration Manual page 171

Device Configuration
Configure the
timeout time
factor of a
Switch
Specify the
maximum
transmission
rate of STP
packets on a
port
Specify the
preference of a
port
Configure
whether to
connect a port
with a
peer-to-peer link
Specify the Path
Cost on a port
Specify the
standard to
follow in Path
Cost calculation
Specify mCheck
for a port
Configure the
protection
functions on a
Switch
Switch E, Enable the STP
Switch F & feature on the
Switch G Switch
Enable the STP
feature on the
port
Configure RSTP
operational
mode
Default Value Note
The Switch, if has In a stable network, it is recommended to
not received any set the timeout time factor to 5, 6, or 7.
Hello packet from Then the Switch will not consider the
the upstream upstream Switch failed unless it has not
Switch for thrice received any Hello packet from it for 5, 6,
the Hello Time, will or 7 times the Hello Time.
consider the
upstream Switch
failed and
recalculate the
spanning tree.
No Ethernet port The more STP packets a port sends within
can send more one Hello Time, the more resources are
than 3 STP packets consumed. It is therefore recommended to
within one Hello limit the transmission rate of STP packets
Time. on a port, preferably to the default value.
All Ethernet ports The port preference plays an important
are at the role in root port selection. You can make a
preference 128. port to be root port by giving it a smallest
preference value.
RSTP can detect The two ports connected with a
automatically peer-to-peer link can rapidly transit to the
whether the forwarding status by sending synchronous
current Ethernet packets, eliminating unnecessary
port is connect to a forwarding delay.
peer-to-peer link.
The Switch gets The path cost of a port is closely related to
the path cost of a the transmission rate of the link the port
port from the link connected with. The larger the link rate is,
rate under the IEEE the smaller the path cost shall be. It is
802.1t standard. recommended to use the default
configuration.
- You can change the operational mode of
a port from STP-compatible to RSTP.
No protection It is recommended to enable the loop
function is enabled protection function on the intermediate
on a Switch. Switches.
The STP feature is The configuration of STP feature status on
disabled from the the port will not take effect if the STP
Switch, but will be feature is disabled from the Switch.
enabled on all
ports once being
enabled on the
Switch.
The Switch works If there are Switches respectively running
in RSTP mode. STP and RSTP on the network, it is
recommended to set the Switch in
STP-compatible mode.
RSTP Configuration 169