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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 time_to_dead field (shown in the EXAMPLES section and in niffconfig -v)
is the amount of time that expires between the red alert being raised and
the interface being declared dead. It is calculated by the traffic monitor
thread as t2 - t1 - (2 * dt).
The interface continues to be monitored every dt seconds in case it comes
back on-line.
You can specify the values for t1, dt, and t2 in seconds (if the
MIF_MILLISECONDS bit is clear in the flags field), or in milliseconds (if
the MIF_MILLISECONDS bit is set). See the EXAMPLES section to see how this
is used.
The traffic monitor thread enforces the following restriction between the
timing parameters:
t2 > t1 + 2dt
dt < t1
t1 >= 0.5
t2 >= 1.1
dt >= 0.2
In the preceding restrictions, the minimum values for t1, dt, and t2 are in
seconds.
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.alert
This is a notice event. It 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.
vendor.hw.net.niff.down
This is an alert event. It is posted when the traffic monitor thread
cannot detect connectivity through a network interface. The interface
is considered dead.
vendor.hw.net.niff.up
This is a notice event. It is posted when the traffic monitor thread
has detected connectivity through a network interface.
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 monitor\n", *av);
bzero(&mif, sizeof (mif));
bcopy(*av, &mif.name[0], MIN(strlen(*av) + 1, sizeof (mif.name) - 1));
mif.t1 = t1;
mif.t2 = t2;
mif.dt = 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 %s\n", *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 ", mif.name,
state[miff.current_state]);
if (mif.flags & MIF_MILLISECONDS)
printf("Timer values in milliseconds...\n");
else
printf("Timer values in seconds...\n");
printf("t1: %d, dt: %d, t2: %d, time to dead: %d,
current_interval:%d, next time: %d\n",
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 monitor\n", *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("could not remove interface");
}
++av;
}
exit(0);
}
SEE ALSO
Routines: ioctl(2)
Files: EVM(5)
Commands: niffconfig(8), niffd(8)
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