IBM 8239 Token-Ring Stackable Hub, Setup And User Manual

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8228 Mode
Normally, the 8239 checks for the presence of phantom insert voltage to determine
when a station is ready to insert into the ring. Some devices such as the IBM 8228
(generically referred to as fanout devices) do not provide phantom voltage. To allow
these types of devices to be inserted into the ring, the 8239 supports a port setting
called
8228_mode. When 8228_mode is enabled, the 8239 will not wait for
phantom voltage to be present but will automatically proceed with the port insertion
process. The default setting for 8228_mode is disabled. To enable 8228_mode,
issue the ENABLE PORT_SETTING 8228_MODE terminal interface command.
Note: Enabling 8228_mode when the port is not connected to a valid device will
cause network disruptions.
Speed Detect and Speed Threshold
The 8239 is able to verify that the station requesting to insert is running at the
same speed as the ring. If the ring speeds of the station and the ring do not match,
the 8239 does not allow the station to insert, preventing disruption to the ring. This
ring speed verification is done only when the speed_detect port setting is enabled.
The default value for speed_detect is enabled. To disable the port from
automatically performing speed detection, issue the DISABLE PORT_SETTING
SPEED_DETECT terminal interface command. Speed detection is configured on a
per-port basis.
When speed_detect is enabled, the 8239 allows a station running at a different
speed to continue to request insertion until it exceeds the speed-mismatch
threshold value. The default value for the speed mismatch threshold is 8 and is
associated with a given hub. To display or change the speed-mismatch threshold
value, issue the DISPLAY HUB or SET HUB SPEED_THRESHOLD terminal
interface commands, respectively.
The speed threshold is configured on a per-hub basis.
Beacon Threshold
When the 8239 detects that a port is the source of a beacon fault, that port is
automatically wrapped. The 8239 has a beacon threshold value to prevent the
same port from causing problems indefinitely on the network. The default value for
the beacon threshold value is 8. To display or change the beacon threshold value,
issue the DISPLAY HUB or SET HUB BEACON_THRESHOLD terminal interface
commands, respectively.
Beacon threshold is configured on a per-hub basis.
Port Up/Down Traps
The 8239 can be configured to send a Port up/down trap whenever a port is
inserted or deinserted. There are two types of configuration parameters associated
with Port up/down traps:
¹
A parameter that is global for the entire hub: You display this parameter by
issuing the DISPLAY TRAP_SETTINGS terminal interface command and
looking at the value of Port Up Down. The default value is enabled. To change
the value of the Port Up Down trap_setting, issue the ENABLE/DISABLE
TRAP_SETTING PORT_UP_DOWN terminal interface command. When the
port_up_down trap_setting is enabled, traps are sent when the port goes up or
down.
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8239 Setup and User’s Guide