Network Configurations and Cable Connections
3-12
893-743-A
Connection in a Model 281xSA/280x cluster is accomplished via Model 988
10BASE-T Workgroup Expansion Cables and the expansion ports on the hubs.
The Model 281xSA hub extends full SNMP functionality to the ports on the
Model 280x hub, providing up to 80 managed ports. Figure 3-10 shows a
typical cluster configuration network with four Model 2803 hubs connected to
the Model 2813SA.
Cluster Operation
A Model 281xSA/280x cluster configuration operates like a single-hub
network, with these two additional conditions:
■
Local hub management is disabled for any Model 280x hub connected to a
Model 281xSA hub through the expansion port.
■
Because of the nature of the expansion port connection, repeater
functionality is distributed among all the units in the cluster, and the
cluster becomes a single logical IEEE 802.3 Ethernet repeater.
If the Model 281xSA hub in a cluster loses power, the cluster configuration
stops operating as a cluster. It loses the SNMP management, and the Model
280x hubs become isolated 16-port segments. If any one of the Model 280x
hubs in a cluster loses power, the remaining hubs maintain the cluster
configuration.
Connecting a Cluster Configuration
In the work area, connections to the network station are the same as those
already described in the earlier section “Cable Connections in the Work Area.”
Follow the appropriate steps for either STP or UTP cable.
To connect the cluster configuration, follow these steps:
1.
Connect the station cables to the hub host ports, as described earlier
in “Ethernet Station Connections.”
NOTE:
A cluster configuration requires one (and only one) Model 281xSA
hub, which supplies four expansion ports. These ports can be used to connect
any combination of Model 2803 and 2804 hubs to the Model 281xSA hub. You
cannot connect Model 280x hubs into a cluster without a Model 281xSA or
Model 281x hub.