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nr(7)
NAME
nr - Redundant Array of Independent Network Adapters (NetRAIN)
DESCRIPTION
The NetRAIN virtual interface configures multiple interfaces on the same
LAN segment into a single interface. One of the real interfaces is always
active while the others remain idle. If the active interface fails, an
idle interface comes online. The failover time is adjustable depending on
your network configuration and operation.
You can configure the NetRAIN interface with the ifconfig command or with
the ioctl system call. See ifconfig(8) for more information. You can also
adjust some NetRAIN default parameters with the sysconfig command. The
SIOCIFADD ioctl parameter creates the NetRAIN virtual interface and adds
the real interfaces to this NetRAIN set. After creating the NetRAIN
virtual interface, one or more real interfaces are attached to it. NetRAIN
uses the Network Interface Failure Finder (NIFF) traffic monitoring
facility to monitor the interfaces. See nifftmt(7) for more information.
You can add or remove individual interfaces from the set, or disassemble
the entire set by using the ifconfig command.
Parameters
The following list of ioctl parameters is used to configure the nr
interface:
SIOCIFADD
Creates the NetRAIN virtual interface if it has not already been
created. This parameter requires an if_nrset structure for the arg
parameter (found in the <net/if.h> file). The if_nrset structure
contains the name of the nr interface (nr0, nr1, ...) and a list of
interfaces to attach to the NetRAIN set. Upon successful completion of
this command, the NetRAIN set is configured and the monitoring thread
is activated. If the command fails, the name of the interface that
could not be added is copied back into the user space buffer (for error
message generation).
The list of NetRAIN interfaces is kept in a static table. The default
size is specified by the nr_maxdev kernel attribute. The interfaces
themselves are numbered from 0 to nr_maxdev-1 (for example, nr0, nr1,
...). To change the size of this table, change the nr_maxdev attribute
for the netrain kernel subsystem by using the sysconfig command. You
must reboot the system for the new value to take effect.
SIOCIFREMOVE
Removes one or all members of the NetRAIN set. This command requires
an ifreq structure with the ifr_name field set to the NetRAIN interface
name (nrx) and the ifr_index field set to the interface index of the
interface to be removed from the set (the ifreq structure is found in
the <net/if.h> file).
You can find the interface index of an interface by using the
SIOCGIFINDEX ioctl. If the specified interface is the current active
interface in the NetRAIN set, the active interface is switched to
another NetRAIN set member. If the NetRAIN set has only one member,
removal of this member is equivalent to disassembling the NetRAIN set.
If the ifr_index field is set to 0, the NetRAIN set is disassembled,
the UP flag is cleared on all members, the hardware address is reset to
the default value, and the hardware address is cleared for the nr
interface. You can reuse the nr interface in a future SIOCIFADD
command.
SIOCIFSWITCH
Forces a manual switch to another interface in the NetRAIN set. This
command requires an ifreq structure passed in the arg field
(<net/if.h>). The ifr_name field can be the nr interface name or the
name of any member in the set. If the name is the nr interface or the
active member, the next member in the set is brought online. If any
other member is specified in the ifr_name field, that interface is
brought online.
SIOCGNRSET
Retrieves the members of a NetRAIN set. This command requires an
if_nrset structure to be passed in the arg field (<net/if.h>). The
nr_name field may be the nr interface name or the name of any member of
the set. Upon return, the nr_name field contains the nr interface name
and the nr_buf field is a list of member names. This buffer must be
large enough to hold all the members or an ENOBUFS error is returned.
SIOCIFAUTOFAIL
Forces the active interface to switch to the next available interface
at regular intervals. It requires an ifreq structure in the arg field.
The ifr_name field must contain the nr interface name and the ifr_value
field contains an integer number of seconds between each switch
operation. A value of zero disables this feature.
The following ioctl parameter is used to control the interface monitoring
frequency. This parameter requires an mif_t structure (found in the
<net/if.h> file). The name field contains the NetRAIN interface name and
the t1 and t2 fields contain timer values.
SIOCIFNRTIMERS
Sets two NetRAIN interface timing parameters in the mif_t structure.
The t1 parameter specifies the time period, in seconds, that the
traffic monitor thread delays between reads of the interface counters
when the network is running normally. If there is no change in the
received byte count for t1 seconds, the traffic monitor thread issues a
yellow alert. The recommended t1 value is 4.
The t2 parameter specifies the traffic-free time period, in seconds,
that must pass before the traffic monitor thread declares the interface
dead. The recommended t2 value is 10 for Ethernet interfaces and 16
for Asynchronous Transfer Mode (ATM) LAN Emulation (LANE) interfaces.
The NetRAIN virtual interface supports all other ioctl parameters. The
NetRAIN driver propagates these commands to the real device driver where
appropriate. See the reference page for each individual driver for more
details.
RESTRICTIONS
NetRAIN has the following restrictions:
· You must construct a NetRAIN set out of interfaces that are currently
idle. This means the interfaces cannot be marked as "up" in the Set up
Network Interface Card(s) dialog box of the SysMan Menu and they
cannot have IP addresses assigned to them.
· You must use two or more of the same type of network interface (FDDI,
ATM LAN Emulation, or Ethernet) dedicated to a single LAN segment. If
you use Ethernet adaptors, theymust all be of the same speed.
· You cannot run LAT over a NetRAIN virtual interface (nr) or any of the
interfaces that compose a NetRAIN set.
· Run separate cables from each network interface to the appropriate hub
or concentrator to provide physically redundant paths back to the
network. This reduces the chance of network failure due to cables
being accidentally unplugged.
· If necessary, you can adjust the timeout values to ensure that NetRAIN
will successfully detect and respond to network failure. You can tune
these parameters with the sysconfig command, ifconfig command, and the
ioctl system call. See nr(7), ifconfig(8), sysconfig(8),
dxkerneltuner(8), and sys_attrs_netrain(5) for more information.
By default, these parameters are tuned for operation over Ethernet,
but it is possible that the default values and other suggested timeout
values will not work in your environment. For example, if you are
connected to a switch, failover time will depend on the switch and its
configuration.
· You must use UNI Version 3.1 when running NetRAIN over LANE to obtain
acceptable failover times with some ATM switches, including the
Gigaswitch. If you use UNI Version 3.0, the failover time might be
long because the T309 timer is set to 90 seconds by default on some
switches. If the T309 timer is adjustable on your switch, you can set
the T309 timer to 10 seconds as in UNI Version 3.1 to try to achieve
acceptable failover times.
ERRORS
EBUSY
A specified interface is already configured.
EINVAL
Possible reasons include:
· The interface list contained an invalid interface type. All
interfaces must be either FDDI or Ethernet.
· The interface list contained interfaces of different types.
Interfaces must be either all FDDI or all Ethernet.
ENOBUFS
NetRAIN could not allocate system memory for the request.
ENXIO
Possible reasons include:
· The NetRAIN interface name was invalid or the unit number was out
of range (0 to nr_maxdev-1).
· An interface that was previously specified already belongs to a
NetRAIN set.
EXAMPLE
The following example creates a NetRAIN set from the specified interfaces.
The first argument is the NetRAIN virtual interface name, nrx. The second
argument is a comma-separated list of real interfaces that are added to the
NetRAIN set.
#include <stdio.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#define IFNAMSZ 16
int main(int argc, char *argv[])
{
struct if_nrset ifnrset;
char *addr;
nrset_t *buf;
int sock,i;
if (argc <= 2) {
printf("Usage: add <nrdev> <dev1>[,dev2...]0);
return(0);
}
/* Load the NetRAIN interface name */
if (--argc > 0) {
argv++;
strcpy(ifnrset.nr_name,*argv);
}
/* Count the members to be included in the NetRAIN set */
if (--argc > 0) {
++argv;
addr = *argv;
ifnrset.nr_cnt = 1;
for (i = 0; addr[i] != ' '; i++) {
if (addr[i] == ',') {
addr[i] = ' ';
ifnrset.nr_cnt++;
}
}
/* Allocate a buffer large enough to hold the interface names */
buf = (nrset_t *)malloc(ifnrset.nr_cnt * IFNAMSZ);
if (buf == NULL) {
perror("malloc: ");
return(0);
}
/* Load the interface array */
for (i=0; i<ifnrset.nr_cnt; i++) {
strcpy(buf[i].name,addr);
addr += strlen(addr)+1;
}
ifnrset.nr_len = ifnrset.nr_cnt * IFNAMSIZ;
ifnrset.nr_buf = (nrset_t *)buf;
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock < 0) {
free(buf);
perror("socket: ");
return(0);
}
if (ioctl(sock, SIOCIFADD, (char *)&ifnrset) != 0) {
close(sock);
free(buf);
perror("SIOCIFADD: ");
return(0);
}
free(buf);
close(sock);
}
return(0);
}
SEE ALSO
Functions: ioctl(2)
Interfaces: alt(7), bcm(7), ee(7), faa(7), fta(7), fza(7), le(7), ln(7),
tu(7)
Commands: nifftmt(7), ifconfig(8), sysconfig(8)
Tuning: sys_attrs_netrain(5)
Network Administration: Connections
System Configuration and Tuning
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Index for
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Alphabetical
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