fddi_config - Displays and modifies the Fiber Distributed Data Interface
/usr/sbin/fddi_config -i interface_name [-c valid_counter_interval_time]
[-d] [-l link_error_monitor_threshold] [-p [1 | 0]] [-r
restricted_token_timeout_time] [-t token_request_time] [-v
valid_transmit_time] [-x [1 | 0]]
Changes or displays the FDDI characteristics for interface_name. You
must provide interface name.
Determines how often the driver counters are updated by the DEFTA
adapter. The default is 1 second. Setting the interval time to zero
(0) disables counter updates. (For the fta FDDI interface only.)
-d Displays the FDDI interface parameters you can set.
Sets the error rate threshold of Link Error Monitor (LEM). The range
for the LEM error rate threshold is an integer power of 10 from 1x10^-5
and 1x10^-8. The default LEM threshold is 1x10^-8.
Sets the ring purger state for the specified FDDI interface. A value
of 1 enables the ring purger ability; a value of 0 disables it.
Sets the Restricted Token Timeout parameter, defining how long a single
restricted mode dialog can last before being terminated. The range for
this parameter is from 0 to 10000 milliseconds. The default value is
Sets the Request Token Rotation Time (T_req) for interface_name. T_req
is used during the ring initialization process to negotiate a Target
Token Rotation Time (TTRT) for the ring. The range for this parameter
is from 4.0 milliseconds to 167.77208 milliseconds. The default value
is 8.0 milliseconds.
Sets the Valid Transmission Time (TVX) timer for a specific FDDI inter-
face. The range for the TVX timer is from 2.5 milliseconds to 5.2224
milliseconds. The default is 2.6214 milliseconds.
Enables (1) or disables (0) full-duplex operation for the fta FDDI
interface. If the full-duplex operation is enabled, the interface can
be in one of the following states: Idle, Request, Confirm, or Opera-
tional. (For the fta FDDI interface only.)
The fddi_config command allows you to display all the parameters you can
set for a specified FDDI interface and to modify one or more parameters
depending on your configuration requirements. If you change a parameter,
all parameters, including unchanged ones, are displayed as confirmation.
You must be superuser to use this command.
Each FDDI interface has a Media Access Control (MAC) entity. As part of
token ring initialization, all MAC entities on the ring participate in a
Claim Token Process to choose a Target Token Rotation Time (TTRT) value.
In this process, each MAC entity bids their own Request TRT (T_req). The
lowest T_req value is chosen as the Negotiated TRT (T_neg) or TTRT for the
ring. Use the netstat -I fza0 -s command to see the Requested TRT and
The TTRT value dictates an approximate, maximum delay for the token to make
a complete loop around the ring. The time it actually takes for a token to
complete a loop around the ring is determined by the stations on the ring
and whether or not the token is captured by a station. If the difference
between the time of the last passing of the token and the current time
exceeds TTRT, stations on the ring may no longer capture the token.
With small TTRT values, stations cannot hold a token very long on its loop
around the ring. This means that each station can transmit only a small
amount of data, but has the opportunity to capture the token more fre-
quently and transmit data. With large TTRT values, stations can hold a
token for a longer period of time, enabling them to transmit more data per
token capture. However, each station must wait a longer period of time to
capture a token. On a heavily loaded ring this might not be desirable.
Each MAC entity also maintains a Valid Transmission Time (TVX) timer to
recover from transient ring error conditions. The TVX timer specifies the
maximum amount of time that can elapse without receiving a valid frame or
nonrestricted token. When this timer expires, the MAC entity assumes that
the ring is no longer operational and initiates the Claim Token process to
reinitialize the ring.
1. To show the parameters you can set for the fza0 interface, enter:
fddi_config -i fza0 -d
2. To change the TRT value for the fta0 interface to 10.2, enter:
fddi_config -t10.2 -i fta0
3. To turn the ring purger off, enter:
fddi_config -p 0 -i mfa0
Files: fta(7), fza(7), mfa(7)