User's Manual

221
Users Manual of CS-6306R
The modification of the priority of the Ethernet port will arise the recalculation of the
spanning tree. We recommend user to use the default value and let RSTP protocol
calculate the path cost of the current Ethernet interface.
When the port speed is 10Mbps, the path cost of the Ethernet interface is 2000000.
When the port speed is 100Mbps, the path cost of the Ethernet interface is
200000.
19.1.6.7 Configuring the Port Priority
If a loop occurs, spanning tree uses the port priority when selecting an interface to put into the forwarding
state. You can assign higher priority values (lower numerical values) to interfaces that you want selected first,
and lower priority values (higher numerical values) that you want selected last. If all interfaces have the same
priority value, spanning tree puts the interface with the lowest interface number in the forwarding state and
blocks the other interfaces.
Follow these configurations in the interface configuration mode:
Command Purpose
spanning-tree rstp port-priorityvalue
Configures the port priority for an
interface.
no spanning-tree rstp port-priority Returns the port priority to the default
value.
The modification of the priority of the Ethernet interface will arise the recalculation
of the spanning tree.
The default Ethernet interface priority is 128.
Configuring MTSP 19.2
19.2.1 MSTP Overview
19.2.1.1 Introduction
Multiple Spanning Tree Protocol (MSTP) is used to create simple complete topology in the bridging LAN.
MSTP can be compatible with the earlier Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol
(RSTP).
Both STP and RSTP only can create sole STP topology. All VLAN messages are forwarded through the only
STP. STP converges too slow, so RSTP ensures a rapid and stable network topology through the handshake
mechanism.
MSTP inherits the rapid handshake mechanism of RSTP. At the same time, MST allows different VLAN to be
distributed to different STPs, creating multiple topologies in the network. In networks created by MSTP,
frames of different VLANs can be forwarded through different paths, realizing the load balance of the VLAN
data.
Different from the mechanism that VLAN distributes STP, MSTP allows multiple VLANs to be distributed to
one STP topology, effectively reducing STPs required to support lots of VLANs.