Cisco Cisco FastHub 412M 10 100 Repeater

The FastHub 400M can store up to 4096 MAC addresses in memory. The optional switched uplink 
modules can store up to 1536 MAC addresses. If there is excessive flooding of unicast packets on these 
devices, your hub or module might have reached its maximum. To clear the MAC address table, 
power-cycle the hub. (CSCdk90641) 

Some 400 FastHubs have improperly terminated 100-MB TXEN signal lines at the extension port. 
If this problem occurs when no extension module is present, 100-MB data can be corrupted. 
Firmware version 1.00.02 and later detect the absence of an extension module and isolate the 
extension port from the hub.

You must purchase and use the FastHub 400 stacking cable (part number WS-C400-CAB-EXP) to 
create a hub stack of interconnected FastHub 400 models. Do not use any other cable for this 
purpose. You can order this cable from your Cisco representative or reseller.

A FastHub 400 does not support modem connections over a telephone line to a PC connected to 
another modem by a telephone line. To connect to a FastHub 400 by using a modem, see your 
modem manual for the correct configuration command syntax. (CSCdk83978)

Before connecting a FastHub 400M model to a modem, configure your modem to ignore input from 
the data terminal equipment (DTE) during dial-out or dial-in. Without this precaution, there is a 
small chance that the modem could disconnect. See your modem manual for the correct 
configuration command syntax. (CSCdk83009)

When changing or moving units within a managed hub stack, note these configuration rules.

The stacking cable connectors are lockable. When you insert the stacking cable, be sure that it snaps 
into place.

The stacking cables are not hot-swappable. You must power down the hub stack before connecting 
or disconnecting a stacking cable. If you connect or disconnect a stacking cable while the power is 
on, power-cycle the stack to ensure correct stack-management operation.

The primary management hub is referred to as the M1 hub. The secondary management hub is 
referred to as the M2 hub.

The M1 hub continuously stores the configuration settings for these stack elements:

Itself.

The three hubs that it has most recently managed (whether or not the hubs are currently being 
managed).

TX and FX switched uplink modules for itself and for each of the three hubs that it has most 
recently managed.

This means that if you remove a hub (other than the M1 hub) or module from the stack and later 
reinstall the same device, the M1 hub might reconfigure that device with its former configuration in 
the stack. Whether or not this happens depends upon whether the stored configuration for that 
particular device has been retained by the M1 hub or overwritten in subsequent changes.