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in.mpathd(1M)		System Administration Commands		 in.mpathd(1M)

       in.mpathd  - daemon for network adapter (NIC) failure detection,	recov-
       ery, automatic failover and failback


       The in.mpathd daemon performs Network Interface Card (NIC) failure  and
       repair  detection.  In the event	of a NIC failure, it causes IP network
       access from the failed NIC to failover to a standby NIC,	if  available,
       or  to  any another operational NIC that	has been configured as part of
       the same	network	multipathing group. Once the failed NIC	 is  repaired,
       all network access will be restored to the repaired NIC.

       in.mpathd  needs	 a special test	address	on each	NIC for	the purpose of
       sending and receiving probes on each  NIC.  Use	the  ifconfig  command
       -failover  option  to configure these test addresses. See ifconfig(1M).
       The test	address	must belong to a subnet	that is	known to the hosts and
       routers on the link.

       The  in.mpathd daemon can detect	NIC failure and	repair by two methods,
       by sending and receiving	ICMP echo requests and replies	on  each  NIC,
       and  by monitoring the IFF_RUNNING flag for each	NIC. The link state on
       some models of NIC is indicated by the IFF_RUNNING flag,	 allowing  for
       faster  failure detection when the link goes down. The in.mpathd	daemon
       considers a NIC to have failed if either	of the above two methods indi-
       cates  failure. A NIC is	considered to be repaired only if both methods
       indicate	the NIC	is repaired.

       The in.mpathd daemon sends the ICMP  echo  request  probes  to  on-link
       routers.	 If no routers are available, it sends the probes to neighbor-
       ing hosts. Thus,	for network failure detection and repair,  there  must
       be  at  least  one neighbor on each link	that responds to ICMP echo re-
       quest probes.

       in.mpathd works on both IPv4 and	IPv6. If IPv4 is plumbed on a NIC,  an
       IPv4 test address is configured on theNIC, and the NIC is configured as
       part of a network multipathing group, then in.mpathd will start sending
       ICMP probes on the NIC using IPv4.

       In  the	case of	IPv6, the link-local address must be configured	as the
       test address. The in.mpathd daemon will not accept a non-link-local ad-
       dress  as  a  test address. If the NIC is part of a multipathing	group,
       and the test address has	been configured, then in.mpathd	will probe the
       NIC for failures	using IPv6.

       Even if both the	IPv4 and IPv6 protocol streams are plumbed, it is suf-
       ficient to configure only one of	the two, that is, either an IPv4  test
       address	or an IPv6 test	address	on a NIC. If only an IPv4 test address
       is configured, it probes	using only ICMPv4. If only an  IPv6  test  ad-
       dress is	configured, it probes using only ICMPv6. If both type test ad-
       dresses are configured, it probes using both ICMPv4 and ICMPv6.

       The  in.mpathd  daemon  accesses	 three	variable  values  in  /etc/de-
       fault/mpathd:   FAILURE_DETECTION_TIME,	 FAILBACK   and	  TRACK_INTER-

       The FAILURE_DETECTION_TIME variable specifies the NIC failure detection
       time  for  the ICMP echo	request	probe method of	detecting NIC failure.
       The shorter the failure detection time, the greater the volume of probe
       traffic.	 The  default  value  of FAILURE_DETECTION_TIME	is 10 seconds.
       This means that NIC failure will	be detected  by	 in.mpathd  within  10
       seconds.	 NIC  failures	detected by the	IFF_RUNNING flag being cleared
       are acted on as soon as the in.mpathd daemon notices the	change in  the
       flag.  The  NIC repair detection	time cannot be configured; however, it
       is defined as double  the value of FAILURE_DETECTION_TIME.

       By default, in.mpathd does failure detection only on NICs that are con-
       figured	as  part  of  a	 multipathing  group. You can set TRACK_INTER-
       FACES_ONLY_WITH_GROUPS to no to enable failure detection	 by  in.mpathd
       on  all	NICs,  even if they are	not part of a multipathing group. How-
       ever, in.mpathd cannot do failover from a failed	NIC if it is not  part
       of a multipathing group.

       The  in.mpathd  daemon  will restore network traffic back to the	previ-
       ously failed NIC, after it has detected a NIC repair. To	disable	 this,
       set the value of	FAILBACK to no in /etc/default/mpathd.

	     Contains default values used by the in.mpathd daemon.

       See attributes(5) for descriptions of the following attributes:

       |      ATTRIBUTE	TYPE	     |	    ATTRIBUTE VALUE	   |
       |Availability		     |SUNWcsr			   |

       ifconfig(1M), attributes(5), icmp(7P), icmp6(7P),

       System Administration Guide, Volume 3

	 IFF_NOFAILOVER	address	address	is not unique and failure detection is
	 not possible

	   Every test address that is configured must be unique	on the system.
	   Otherwise  in.mpathd	 cannot	 do  failure detection.	Since the IPv6
	   test	address	is a link-local	address, which in turn is derived from
	   the ethernet	address, each NIC must have a unique MAC address.

	 NIC  interface_name  of  group	group_name is not plumbed for IPv[4|6]
	 and may affect	failover capability

	   All NICs in a multipathing group must be homogeneously plumbed. For
	   example,  if	 a NIC is plumbed for IPv4, then all NICs in the group
	   must	be plumbed for IPv4. The streams modules pushed	 on  all  NICs
	   must	be identical.

	 Failures  cannot  be  detected	on interface_name as no	IFF_NOFAILOVER
	 address is available

	   Every NIC that is configured	as part	of a multipathing  group  must
	   have	 a  test  address,  which can be either	IPv4 or	IPv6, or both.
	   Otherwise in.mpathd cannot probe the	NIC, and this message is  dis-

	 Invalid failure detection time	assuming default 10000

	   An  invalid value was encountered for FAILURE_DETECTION_TIME	in the
	   /etc/default/mpathd file.

	 Too small failure detection time of time assuming minimum 100

	   The minimum value that can be specified for	FAILURE_DETECTION_TIME
	   is currently	100 milliseconds.

	 Invalid value for FAILBACK value

	   Valid values	for the	boolean	variable FAILBACK are yes or no.


	   Valid    values    for    the    boolean    variable	  TRACK_INTER-
	   FACES_ONLY_WITH_GROUPS are yes or no.

	 Cannot	meet requested failure detection time of time ms  on  (inet[6]
	 interface_name) new failure detection is time ms

	   The	round  trip  time for ICMP probes is higher than the specified
	   failure detection time. The network is probably  congested  or  the
	   probe  targets  are	loaded.	 in.mpathd automatically increases the
	   failure detection time to whatever it can achieve under these  con-

	 Improved failure detection time time ms on (inet[6] interface_name)

	   The round trip time for ICMP	probes has now decreased and in.mpathd
	   has lowered the failure detection time correspondingly.

	 NIC failure detected on interface_name

	   in.mpathd has detected NIC failure on interface_name, and  has  set
	   the IFF_FAILED flag on NIC interface_name.

	 Successfully  failed  over  from  NIC	interface_name1	 to NIC	inter-

	   in.mpathd has caused	the network traffic to failover	from  NIC  in-
	   terface_name1  to  NIC interface_name2, which is part of the	multi-
	   pathing group.

	 NIC repair detected on	interface_name

	   in.mpathd has detected that NIC interface_name is repaired and  op-
	   erational. If the IFF_FAILED	flag on	the NIC	was previously set, it
	   will	be reset.

	 Successfully failed back to NIC interface_name

	   in.mpathd has restored network traffic back to NIC  interface_name,
	   which is now	repaired and operational.

	 The link has gone down	on interface_name

	   in.mpathd  has  detected  that  the IFF_RUNNING flag	for NIC	inter-
	   face_name has been cleared, indicating the link has gone down.

	 The link has come up on interface_name

	   in.mpathd has detected that the IFF_RUNNING	flag  for  NIC	inter-
	   face_name has been set, indicating the link has come	up.

SunOS 5.9			  3 Dec	2001			 in.mpathd(1M)


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