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nifftmt(7)
NAME
nifftmt - Traffic monitoring for the Network Interface Failure Finder
(NIFF)
SYNOPSIS
#include <net/if.h>
#include <sys/ioctl.h>
DESCRIPTION
The NIFF traffic monitor thread checks the connectivity of network
interfaces and issues events when it detects a change in an interface's
connectivity. It does this by monitoring the interface's data counters and
using the event management (EVM) framework to inform interested subscribers
of connectivity-related events.
Typically, the traffic monitor looks at a network interface's counters once
every several seconds and issues an event based on what it determines from
their value.
There are two basic types of events. The first type occurs when an
interface is added to the list of events already being monitored. In this
case, the traffic monitor sends an event to indicate the interface is up
and running. The other type of event occurs when the traffic monitor does
not see any traffic coming into the interface for a period of time. The
traffic monitor thread uses timing parameters to determine when to issue an
event.
TIMING PARAMETERS
The timing parameters for the traffic monitor are passed to the NIFF
traffic monitor thread using the ioctl(2) system call and the
monitored_interface structure defined in the <net/if.h> file. See ioctl(2)
for further information.
The following lists the NIFF traffic monitor thread timing parameters:
name The name of an interface that is to be monitored. For example,
tu0 and fta0.
t1 Specifies the time period, in seconds, that the traffic monitor
thread delays between reads of the interface counters when the
network is running normally. The traffic monitor thread issues a
yellow alert when there is no change in the received byte count
for a period of t1 seconds. By default, niffconfig sets this
time period to 20 seconds. This corresponds to the niffconfig -t
option.
dt Specifies the time period, in seconds, that the traffic monitor
thread delays between reads of the interface counters when it
suspects there is a connectivity problem. This number must be
smaller than the number given for the t1 option. The traffic
monitor thread issues an orange alert when there is no change in
the received byte count for t1 plus dt seconds. If another dt
seconds goes by with no change in the received byte count, the
traffic monitor thread issues a red alert. By default,
niffconfig sets this time period to 5 seconds. This corresponds
to the niffconfig -d option.
t2 The total number of traffic-free seconds that must pass before
the traffic monitor thread declares the interface to be dead.
After t2 seconds with no change in the interface's received byte
count, the traffic monitor thread issues a dead event. This
number must be equal to at least the sum of t1 and two times t2.
By default, niffconfig sets this time period to 60 seconds. This
corresponds to the niffconfig -o option.
The interface continues to be monitored every dt seconds in case it comes
back on-line.
The traffic monitor thread enforces the following restriction between the
timing parameters:
t2 > t1 + 2dt, and dt < t1
It is up to the subscribers to take action based on the events that the
traffic monitor reports. For example, the niffd daemon attempts to generate
traffic that the suspect interface's receiver will pick up. Other
subscribers may want to take action such as to migrate applications to
another node or to activate another network interface to replace the
suspect interface.
The traffic monitor responds to the following ioctl(2) commands:
#include <net/if.h>
mif_t arg;
ioctl(fd, command, arg);
As shown in the previous example, mif_t is a monitored interface structure.
Most commands require the name field of the mif_t structure to be filled
in. The applicable commands are:
SIOCTMTADD
Adds the named interface to the list of interfaces being
monitored. The timing parameters must be filled in as noted in
the TIMING PARAMETERS section. If this is the first interface to
be added, the SIOCTMTADD command also starts the thread.
SIOCTMTREMOVE
Removes the named interface from the list of monitored
interfaces. If the last interface in the list of those being
monitored is removed, the thread is stopped.
SIOCTMTMODIFY
Modifies the timing parameters for the named interface. The
relationship between the timing parameters must be as noted in
the TIMING PARAMETERS section.
SIOCTMTHOWMANY
Returns the number of bytes required to store a complete status
dump of the interfaces currently being monitored. See
SIOCTMTDUMP. This command does not require a third argument to
ioctl.
SIOCTMTSTATUS
Fills in the mif_t structure for the named interface, thereby
sending its status back to the caller.
SIOCTMTDUMP
Fills in the user-supplied buffer with the status of each
interface being monitored.
SIOCTMTWALK
Used for debugging. Causes the kernel to print the status of
each interface that is currently being monitored.
EVENTS
The traffic monitor posts the following events:
vendor.hw.net.niff.down
This event is posted when the traffic monitor thread declares an
interface to be dead.
vendor.hw.net.niff.up
This event is posted when the traffic monitor thread has not seen
traffic on an interface for t1 seconds. This event is also
posted every dt seconds until either traffic is detected or the
traffic monitor determines that the interface is dead.
RETURN CODES
EBUSY An SIOCTMTADD was attempted on an interface that is already being
monitored.
ENOBUFS The kernel could not allocate memory to copy in the user's
buffer.
EINVAL The relationship between the timing parameters is not correct, or
an invalid command was given to the traffic monitor.
ENXIO An SIOCTMTADD, SIOCTMTSTATUS, or SIOCTMTMODIFY command was
attempted on an interface that is not currently being monitored.
EXAMPLES
The following example illustrates the use of a few NIFF ioctl functions:
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/param.h>
#include <net/if.h>
#include <errno.h>
/* these strings map to the "state" enum */
char *state[] = {"INIT", "GREEN", "YELLOW", "ORANGE", "RED", "DEAD"};
/* usage: niff_example tu0 tu1 tu2...
* must supply the name of at least one
* network interface
*/
main(int ac, char **av)
{
int t1 = 20, t2 = 60, dt = 5;
char **oldav;
mif_t mif;
int s;
oldav = ++av;
s = socket(AF_INET, SOCK_DGRAM, 0);
/* tell the traffic monitor to start watching these interfaces */
while (*av) {
printf("Adding interface %s to the traffic monitor0, *av);
bzero(&mif, sizeof (mif));
bcopy(*av, &mif.name[0], MIN(strlen(*av) + 1, sizeof (mif.name - 1)));
mif.current_interval = mif.next_time = mif.t1 = t1;
mif.t2 = t2;
mif.dt = dt;
mif.time_to_dead = mif.t2 - mif.t1 + 2 * mif.dt;
mif.flags = 0;
if (ioctl(s, SIOCTMTADD, &mif) < 0) {
perror("couldn't add interface");
break;
}
++av;
}
av = oldav;
/* get the status of the interfaces - NB will probably always
* be in the "init" state
*/
while (*av) {
printf("checking the status of interface %s0, *av);
bzero(&mif, sizeof (mif));
bcopy(*av, &mif.name[0], MIN(strlen(*av) + 1, sizeof (mif.name - 1)));
if (ioctl(s, SIOCTMTSTATUS, &mif) < 0) {
perror("couldn't get status for interface");
break;
} else
printf("Interface: %05s, state: %s, t1: %d, dt: %d, t2: %d, time to
dead: %d, current_interval:%d, next time: %d0,
mif.name, state[mif.current_state], mif.t1, mif.dt, mif.t2,
mif.time_to_dead, mif.current_interval, mif.next_time);
++av;
}
av = oldav;
/* tell the traffic monitor to stop watching */
while (*av) {
printf("deleting interface %s from the traffic monitor0, *av);
bzero(&mif, sizeof (mif));
bcopy(*av, &mif.name[0], MIN(strlen(*av) + 1, sizeof (mif.name - 1)));
if (ioctl(s, SIOCTMTREMOVE, &mif) < 0) {
perror("couldn't remove interface");
}
++av;
}
exit(0);
}
RELATED INFORMATION
ioctl(2), EVM(5), niffconfig(8), niffd(8)
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