3Com 5500 SI - Switch - Stackable, Configuration Manual

Page: 545 / 686

RSTP Configuration 545
Specify a Switch
as the root or
backup root
bridge The role of the
current Switch as the
root or backup root
bridge depends on
the STP calculation. A Switch can be made the root bridge by
specifying its Bridge preference to 0.
Configure the
Bridge
preference of a
Switch The Bridge
preference of a
Switch is 32768. A Switch can be made the root bridge by
specifying its Bridge preference to 0.
Specify Forward
Delay, Hello
Time, and Max
Age Forward Delay fixes
on 15 seconds, Hello
Times on 2 seconds,
and Max Age on 20
seconds. The other Switches copies the
configuration on the root bridge with
respect to these time parameters. You can
therefore only configure them on the root
bridge. The default values are highly
recommended.
Specify the
maximum
transmission
rate of STP
packets on a
port No Ethernet port can
send more than 3 STP
packets within one
Hello Time. The more STP packets a port sends within
one Hello Time, the more resources are
consumed. It is therefore recommended to
limit the transmission rate of STP packets
on a port, preferably to the default value.
Configure
whether to
connect a port
with a
peer-to-peer link RSTP can detect
automatically
whether the current
Ethernet port is
connect to a
peer-to-peer link. The two ports connected with a
peer-to-peer link can rapidly transit to the
forwarding status by sending synchronous
packets, eliminating unnecessary
forwarding delay.
Specify the Path
Cost on a port
Specify the
standard to
follow in Path
Cost calculation
The Switch gets the
path cost of a port
from the link rate
under the IEEE 802.1t
standard. The path cost of a port is closely related to
the transmission rate of the link the port
connected with. The larger the link rate is,
the smaller the path cost shall be. It is
recommended to use the default
configuration.
Specify mCheck
for a port - You can change the operational mode of a
port from STP-compatible to RSTP.
Configure the
protection
functions on a
Switch No protection
function is enabled
on a Switch. It is recommended to enable the Root
protection function on the root bridge.
Switch C
and
Switch D Enable the STP
feature on the
Switch
Enable the STP
feature on the
port
The STP feature is
disabled from the
Switch, but will be
enabled on all ports
once being enabled
on the Switch. The configuration of STP feature status on
the port will not take effect if the STP
feature is disabled from the Switch.
Configure RSTP
operational
mode The Switch works in
RSTP mode. If there are Switches respectively running
STP and RSTP on the network, it is
recommended to set the Switch in
STP-compatible mode.
Configure the
Bridge
preference of a
Switch The Bridge
preference of a
Switch is 32768. A Switch can be made the designated
bridge of the downstream Switches by
specifying an appropriate Bridge preference
in the STP calculation.
Table 595 RSTP Configuration (continued)
Device Configuration Default Value Note