H3C Technologies H3C Intelligent Management Center - Manual (Page 377)

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When the Root Type is set to Primary or Secondary, the bridge Priority cannot be set.
7. Enter the Admin VLAN ID for this instance in the Admin VLAN ID field. You can enter more than one
VLAN ID. Separate each VLAN ID with a comma (,). You can also enter VLAN IDs by range, using
a dash (-) between the beginning and ending of the VLAN ID range.
Admin VLAN ID is used to tie an MSTI to a specific VLAN. The configured VLAN-to-instance
mapping does not take effect until MSTP is enabled.
8. Click OK to accept your changes.
9. Click Close to close the MSTI window.
For more information about configuring the spanning tree feature, refer to your switch vendor's
documentation.
Modifying port MSTP settings
To modify port configuration of the Multiple spanning tree Protocol (MSTP) settings:
1. Click the MSTP link located under the Protocol Management section of the right navigation tree on
the selected router or switch's Device Details page.
2. Click the Port MSTP tab located at the top of the page to navigate to the Port MSTP page.
3. Locate the port you want to modify the MSTP settings for from the list provided.
4. Click the Modify icon associated with the instance you want to modify.
5. Select the port priority for the selected port from the Priority list.
The priority of a port is an important factor in determining whether the port can be elected as the
root port of a device during the spanning tree calculation process. If all other conditions are equal,
the port with the highest priority is elected as the root port. On an MSTP-enabled device, a port can
have different priorities in different MSTIs, and the same port can play different roles in different
MSTIs, so that data of different VLANs can be propagated along different physical paths, thus
implementing per-VLAN load balancing. When the priority of a port is changed, MSTP
re-computes the role of the port and initiate a state transition. Generally, a configured lower
priority value indicates a higher priority of the port.
If all the ports of a switch have the same port priority value, the port priorities are determined by
the port indexes. You can set port priority values based on the actual networking requirements. The
default port priority is 128.
6. Enter the path cost to the root bridge in the Path Cost to Root Bridge field.
The Path Cost to Root Bridge parameter is related to the rate of port-connected links. On a switch
supporting MSTP, the port may have varying path costs in different spanning tree instances so that
traffic from different VLANs can be forwarded along different physical links to implement
per-VLAN load sharing. By default, MSTP calculates the path cost of each port.
7. To enable CIST Edge Port, select Enable from the CIST Edge Port field.
The CIST Edge Port option is only applicable when the MSTI is a CIST. Edge port indicates that the
port is neither directly connected to any switch nor indirectly connected to any switch through the
port-connected network. When the operator specifies one port as the edge port and when the port
migrates from the congestion state to the forwarding state, fast migration can be implemented
without any delay. The user can only configure the port connecting the terminal as the edge port.
If BPDUs from other ports are received on the edge port, the port becomes a non-edge port again.
This parameter is valid for all spanning tree instances. In other words, when the port is configured
as an edge port or non-edge port, the port is configured as an edge port or non-edge port on the
CIST and all MSTIs. When the port receives BPDUs, the port actually operates as a non-edge port
even it if is configured as the edge port by the operator. By default, all Ethernet ports of a switch
are non-edge ports.