3Com 5500-SI Configuration Manual page 546

546 C 26: RSTP C
HAPTER ONFIGURATION
Table 595 RSTP Configuration (continued)
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
and Switch
Switch G
Enable the STP
feature on the
port
Configure RSTP
operational
mode
Configure the
timeout time
factor of a
Switch
Default Value Note
The Switch, if has not In a stable network, it is recommended to
received any Hello set the timeout time factor to 5, 6, or 7.
packet from the Then the Switch will not consider the
upstream Switch for upstream Switch failed unless it has not
thrice the Hello Time, received any Hello packet from it for 5, 6,
will consider the or 7 times the Hello Time.
upstream Switch
failed and recalculate
the spanning tree.
No Ethernet port can The more STP packets a port sends within
send more than 3 STP one Hello Time, the more resources are
packets within one consumed. It is therefore recommended to
Hello Time. limit the transmission rate of STP packets
on a port, preferably to the default value.
All Ethernet ports are The port preference plays an important role
at the preference in root port selection. You can make a port
128. 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 current forwarding status by sending synchronous
Ethernet port is packets, eliminating unnecessary
connect to a forwarding delay.
peer-to-peer link.
The Switch gets the The path cost of a port is closely related to
path cost of a port the transmission rate of the link the port
from the link rate connected with. The larger the link rate is,
under the IEEE 802.1t the smaller the path cost shall be. It is
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 in If there are Switches respectively running
RSTP mode. STP and RSTP on the network, it is
recommended to set the Switch in
STP-compatible mode.
The Switch, if has not In a stable network, it is recommended to
received any Hello set the timeout time factor to 5, 6, or 7.
packet from the Then the Switch will not consider the
upstream Switch for upstream Switch failed unless it has not
thrice the Hello Time, received any Hello packet from it for 5, 6,
will consider the or 7 times the Hello Time.
upstream Switch
failed and recalculate
the spanning tree.