A10E/A28E/A28F Configuration Guide
root bridge or backup bridge of CIST if instance-id is 0 or parameter instance
instance-id is omitted.
The roots in device instances are independent mutually, that is to say, they cannot
only be the root bridge or backup bridge of one instance, but also the root bridge
or backup bridge of other spanning tree instances. However, in the same
spanning tree instance, the same device cannot be used as the root bridge and
backup bridge at the same time.
You cannot assign two or more root bridges for one spanning tree instance, but
can assign several backup bridges for one spanning tree. Generally speaking, you
had better assign one root bridge and several backup bridges for a spanning tree.
7.5.7 Configuring device interface and system priority
Whether the interface is selected as root interface can be judged by interface priority. Under
the identical condition, the smaller priority interface will be selected as root interface. An
interface may have different priorities and play different roles in different instances.
The device Bridge ID decides whether it can be selected as root of spanning tree. Configuring
smaller priority helps get smaller device Bridge ID and designate the A10E/A28E as root. If
priority is identical, the A10E/A28E with smaller MAC address will be selected as root.
Similar to configuring root and backup root, priority is independent mutually in different
instances. You can confirm priority instance through parameter instance instance-id.
Configure bridge priority for CIST if instance-id is 0 or parameter instance instance-id is
omitted.
Configure interface priority and system priority for the A10E/A28E as below.
Enter global configuration mode.
Alpha-A28E(config)#interface port
port-id
Enter physical layer interface
configuration mode.
Alpha-A28E(config-port)#spanning-
tree [ instance
instance-id
]
priority
priority-value
Alpha-A28E(config-port)#exit
Set interface priority for a STP
instance.
Alpha-A28E(config)#spanning-tree
[ instance
instance-id
] priority
priority-value
Set system priority for a STP
instance.
The value of priority must be multiples of 4096, like 0, 4096, 8192, etc. It is 32768 by
default.
7.5.8 Configuring network diameter for switch network
Network diameter indicates the nodes number on the path has the most device number in
switch network. In MSTP, network diameter is valid only to CIST, and invalid to MSTI
instance. No matter how many nodes in a path in one domain, it is considered as just one node.
Actually, network diameter should be defined as the domain number in the path crossing the
most domains. The network diameter is 1 if there is only one domain in the whole network.
To Next Page
Loading...