<!-- ""@(#)pnm 1.2 97/10/16 Sun Microsystems Inc"" >
 
<title>Public Network Management</title>
<h1>Public Network Management</h1>

The Public  Network Management (PNM) component  of Sun Cluster 2.0 has
two primary  functions - to  monitor the status of configured adapters
on a host   and report general  adapter  or network  failures, and  to
transparently failover to configured backup adapters  on a host in the
event of  failure  of the  primary adapter. PNM  periodically monitors
network  statistics on the  set of public interfaces  of a node and in
the case of  any abnormalities will  attempt to distinguish  between a
quiescent network, faulty network, and a faulty network interface.<p>

The results  of the PNM monitoring  are used by  various components in
Sun Cluster 2.0.   The network adapter  failover component of PNM uses
the  PNM monitoring  results to  decide if  adapter failover  would be
useful.  No adapter failover is  performed if the network is diagnosed
to be faulty. Fault  probes associated with <a href=sc/ha">HA</a> data
services and  the  hactl(1m) <a  href="sc/haapi">HA Data  Services API
</a>utility make use of the PNM utility  to diagnose the cause of data
service  failure.  The information returned  by PNM  is used to decide
whether to migrate the data service  and where to  migrate it to.  The
syslog  messages written by the  PNM  facility on detection of adapter
failures is picked up by the  cluster monitor GUI, which translates it
into the appropriate pictorial depiction  on the GUI, thereby enabling
the system administrator to take corrective action.<p>
