XS26GS Managed Optical Ethernet Switch User Manual
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Priority, and Root Guard for each port, and also can set Path Cost and Priority.
Edge Port
: selects
Enabled
to configure the specified Ethernet port as an edge port. By
default, all Ethernet ports are non-edge ports.
An edge port is such a port that is directly connected to a user terminal instead of
another switch or network segment. Rapid transition to the forwarding state is applied to
edge ports, 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
: choose 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
: specified to automatically determine whether the link connected to the
specified Ethernet port is a point-to-point link.
Protocol
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. This argument ranges from 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 disconnected from the link).