CANOGA PERKINS 9161 Network Interface Device - Manual (Page 39)

Using the Software 9161 Network Interface Device User’s Manual
Managing the Network Interface
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3.5 Managing the Network Interface
The Switch Configuration menu offers options to set network parameters. Ethernet bridges or
switches use the Spanning Tree Protocol (STP), an algorithm that creates a logical topology that
connects all network segments and ensures only one path between any two stations (reference
Table 3-3). When STP is enabled, the 9161 monitors the incoming data packets and periodically
sends Bridge Protocol Data Units (BPDU). STP monitors the incoming BPDUs to detect any
loops. If the same BPDU arrives on two ports, STP blocks one port to remove the loop. Because
this tree-like structure spans all nodes in the network, it is called Spanning Tree. Figure 3-4
shows a typical STP application.
NOTE: For details on the Spanning Tree Algorithm, see the IEEE 802.1
specifications.
Figure 3-4. Typical Spanning Tree Application
In a service provider environment, you can include VLANS from different customers. The tagging
and double tagging features, when enabled, keep the ID tag on a packet as it exits a port; or
when disabled, strip the ID tag as it exits a port. The customer's tag for a VLAN is assigned
through the VLAN; the double (service provider's) tag is derived from the PVID and assigned
before the packet exits the 9161. See Figure and follow these guidelines:
• Enable double tagging on the service provider port and disable it on the customer's port.
• The SP tag priority is derived from the port priority.
• If you set up Pbit translation, the translation occurs before the Pbit is copied to the SP tag
Table 3-3. Network Spanning Tree Parameters Options
Menu Item Description
1. Global Spanning Tree Parameters Set the network-wide parameters
2. Multiple Spanning Tree Parameters Set and view Multiple Spanning Tree instances
3. Global Spanning Tree Report View current network-wide parameters
5. VLAN Configuration Set the VLAN parameters