3 Web-based Management
because no loop can be incurred by network topology change on edge ports. The spanning
tree protocol allows a port to enter the forwarding state rapidly by setting it to be an edge port,
and it is recommended to configure the Ethernet ports connected directly to user terminals as
edge ports, so that they may enter the forwarding state immediately.
Normally, configuration BPDUs cannot reach an edge port because the port is not connected
to another switch. But, in case that BPDU guard function is disabled on an edge port,
configuration BPDUs sent deliberately by a malicious user may reach the port. If an edge port
receives a BPDU, it changes itself to be a non-edge port.
P2P: select from Force_True, Force_False, and Auto.
Force_True: specifies that the link connected to the specified Ethernet port is a
point-to-point link.
Force_False: specifies that the link connected to the specified Ethernet port is not a
point-to-point link.
Auto: automatically determines whether the link connected to the specified Ethernet port
is a point-to-point link.
Migration: For backward compatibility with switches running 802.1d, RSTP selectively sends
802.1d configuration BPDUs and TCN BPDUs on per-port basis.
When a port is initialized, the migration-delay timer is started, and RSTP BPDUs are sent in
this time interval. When this timer is active, the switch processes all BPDUs received on the
port and ignores the protocol type.
If the switch receives an 802.1d BPDU after the port's migration-delay timer is expired, it
assumes that it is connected to an 802.1d switch and starts using only 802.1d BPDUs.
However, if the RSTP switch is using 802.1d BPDUs on a port and receives an RSTP BPDU
after the timer is timed out, it restarts the timer and starts using RSTP BPDUs on that port.
Tx Hold Count: the maximum number of configuration BPDUs a port can send in each Hello
time. It is in the range of 1 to 10 and is 3 by default.
External Cost: sets the path cost of the specified port. It is in the range of 1 to 200000000,
the default value is 0 (Auto).
Priority: port priority, it is in the range of 0 to 255; the default value is 128.
Root Guard: by default, the root protection function is disabled.
Due to configuration error or malicious attack, the root bridge in the network may receive
configuration BPDUs with priorities higher than that of a root bridge, which will cause a new
root bridge to be elected and network topology jitter will occur. In this case, data flows that
should have been transmitted along a high-speed link may be led to a low-speed link.
This problem can be resolved by enabling the root protection function.
Root-protection-enabled ports can only be kept as designated ports. When a port of this type
receives configuration BPDUs with higher priorities, that is, when it is to become a
non-designated port, it turns to the discarding state and stops forwarding packets (as if it were
To Next Page
Loading...
Need help?
General