fddi_config(8)fddi_config(8)NAMEfddi_config - Displays and modifies the Fiber Distributed Data Inter‐
face (FDDI) parameters
SYNOPSIS
/usr/sbin/fddi_config -i interface_name [-c valid_counter_inter‐
val_time] [-d] [-l link_error_monitor_threshold] [-p [1 | 0]] [-r
restricted_token_timeout_time] [-t token_request_time] [-v valid_trans‐
mit_time] [-x [1 | 0]]
OPTIONS
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.) 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
1000 milliseconds. 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 interface. 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 Operational. (For the fta FDDI interface only.)
DESCRIPTION
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 param‐
eters 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 Negotiated TRT.
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 cap‐
ture 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
frequently 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.
EXAMPLES
To show the parameters you can set for the fza0 interface, enter:
fddi_config-i fza0 -d To change the TRT value for the fta0 interface
to 10.2, enter: fddi_config-t10.2 -i fta0 To turn the ring purger off,
enter: fddi_config-p 0 -i mfa0
SEE ALSO
Files: fta(7), fza(7), mfa(7)fddi_config(8)
