3Com SuperStack 4 Configuration Manual page 232

244 C 10: RSTP C
HAPTER ONFIGURATION
Device Configuration
Specify Forward
Delay, Hello
Time, and Max
Age
Specify the
maximum
transmission
rate of STP
packets on 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 C & Enable the STP
Switch D feature on the
Switch
Enable the STP
feature on the
port
Configure RSTP
operational
mode
Configure the
Bridge
preference of a
Switch
Configure the
timeout time
factor of a
Switch
Default Value Note
Forward Delay fixes The other Switches copies the
on 15 seconds, configuration on the root bridge with
Hello Times on 2 respect to these time parameters. You can
seconds, and Max therefore only configure them on the root
Age on 20 bridge. The default values are highly
seconds. recommended.
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.
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 Root
function is enabled protection function on the root bridge.
on a Switch.
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.
The Bridge A Switch can be made the designated
preference of a bridge of the downstream Switches by
Switch is 32768. specifying an appropriate Bridge
preference in the STP calculation.
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.