CTC Union FRM220-100AS-1, User Manual

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CHAPTER 4
PROVISIONING VIA WEB BASED MANAGEMENT
1. Configuration BPDU (CBPDU), used for Spanning Tree computation
2. Topology Change Notification (TCN) BPDU, used to announce changes in the network topology
3. Topology Change Notification Acknowledgment (TCA), used to acknowledge changes
The Bridge Priority is a customizable value that you can use to influence which switch becomes the
root bridge. The switch with the lowest priority, which means lowest BID, becomes the root bridge
(the lower the priority value, the higher the priority). The default value for the priority is 32768
(0x8000). The priority range is between 1 and 65536 (0x0001 to 0xFFFF); with 1 as the highest
priority.
Maximum Age Time
, referred to by the switch as Max Age , is the amount of time a switch will
retain a BPDU's contents before discarding it. The default is 20 seconds. It also influences the
bridge table aging timer during the Topology Change Notification process.
Hello Time
is the time interval (number of seconds between) at which the root bridge transmits
configuration BPDUs.
When a device is first attached to a switch port, it will not immediately start to forward data. It will
instead go through a number of states while it processes BPDUs and determines the topology of
the network. The time spent in the listening and learning states is determined by a value known as
the
Forward Delay (default 15 seconds and set by the root bridge).
These timers should not be changed lightly. If you decide to change any or all of these timers, the
change must be configured on the root bridge! The root bridge will inform the non-root switches of
the change via BPDUs.
Within a bridge (switch) there will also be multiple ports (interfaces) that can be additionally
assigned priority within the bridge (switch). By default, the lowest port number will have the
highest priority. In the case of
100AS-1 , that would be the first fiber port, port 1. The ports may
change assigned priority under the Port Priority pull-down for each port. The Port Priority plus the
port number are combined to give the Port ID . For example, Port Priority of 128 (0x80) plus the
port number (first fiber port 1 = 01) will give a Port ID of 8001 . Port Priority can be set and the
results of the Port ID follow according to this conversion table:
Dec
0 16 32 48 64 80 96 112 128 144 160 176 192 208 224 240
Hex
00 10 20 30 40 50 60 70 80 90 A0 B0 C0 D0 E0 F0
The default port
Path Cost in 100AS-1 is set at 0 (auto) and can be set in a valid range up to
200,000,000.