User's Manual

2-12 Configuring, Installing, and Using Carrier Infrastructure
Configuring switches
This section describes configuration of the following switches:
• Switch connecting base stations at the cell site
• Head end switch
• ISP switch
Configuring the switch at the cell site
At the cell site, the network access provider must program a port on the switch to be a WAN
trunk to the head end switch.
Configuring the head end switch
WAN trunk ports on the head end switch must be configured to accept traffic from the cell
sites.
The head end switch then splits the traffic to the Management VLAN and the ISP VLANs.
The network access provider configures edge ports on the head end switch with the
Management VLAN ID, and the IDs of all the ISP VLANs.
Configuring the ISP switch
The ISP switch must be configured with the IDs of VLANs provided to the ISP by the
network access provider. A port on the switch is also configured with the ID of the control
VLAN.
Selecting backhaul links and circuits
Network access providers must select the links or circuits that connect the cells to the
backbone network. Each cell may have one or more base stations, and each base station
serves a sector within a cell. Service providers typically deploy cells in four or six sectors.
Depending on the upstream/downstream ratio selected and the configuration of the sector
covered by the base station, downlink capacity of up to 8 mb per second and uplink capacity
up to 4 mb per second may be required.
Adequate backhaul facilities must be provided to support this throughput.
Selecting links based on maximum rate needed
You can choose a link based on the maximum bit-transfer rate you might need. For example,
you might use DS-3 circuits to connect cells to a switch, and then connect those switches
together, using the appropriate higher-rate links.
Selecting links based on another rate
You might want to choose a link providing another data transfer rate. The link you choose
might depend on the expected and actual traffic rates for a given cell.
Choosing this option means you get lower cost circuits, but you also might get lower
throughput, increased response latency, and so on.