<!-- Module User's Guide -->

<chapter>
	<chapterinfo>
	<revhistory>
		<revision>
		<revnumber>$Revision: 1827 $</revnumber>
		<date>$Date: 2007-03-12 17:22:53 +0200 (Mon, 12 Mar 2007) $</date>
		</revision>
	</revhistory>
	</chapterinfo>
	<title>User's Guide</title>
	
	<section>
		<title>Overview</title>

		<para>The SNMPStats module provides an SNMP management interface
		to OpenSER.  Specifically, it provides general SNMP queryable 
		scalar statistics, table representations of more complicated data such as 
		user and contact information, and alarm monitoring capabilities.
		</para>
		<section>
			<title>General Scalar Statistics</title>
			<para>
			The SNMPStats module provides a number of general scalar statistics.  
			Details are available in OPENSER-MIB, OPENSER-REG-MIB, 
			OPENSER-SIP-COMMON-MIB, and OPENSER-SIP-SERVER-MIB.  But briefly, 
			these scalars are:
			</para>
			<para>
			openserSIPProtocolVersion, openserSIPServiceStartTime, openserSIPEntityType,
			openserSIPSummaryInRequests, openserSIPSummaryOutRequest, 
			openserSIPSummaryInResponses, openserSIPSummaryOutResponses,
			openserSIPSummaryTotalTransactions, openserSIPCurrentTransactions, 
			openserSIPNumUnsupportedUris, openserSIPNumUnsupportedMethods, 
			openserSIPOtherwiseDiscardedMsgs, openserSIPProxyStatefulness
			openserSIPProxyRecordRoute, openserSIPProxyAuthMethod, 
			openserSIPNumProxyRequireFailures, openserSIPRegMaxContactExpiryDuration,
			openserSIPRegMaxUsers, openserSIPRegCurrentUsers, 
			openserSIPRegDfltRegActiveInterval, openserSIPRegAcceptedRegistrations,
			openserSIPRegRejectedRegistrations, openserMsgQueueDepth.
			openserCurNumDialogs, openserCurNumDialogsInProgress, 
			openserCurNumDialogsInSetup, openserTotalNumFailedDialogSetups
			</para>
			<para>
			There are also scalars associated with alarms.  They are as follows:
			</para>

			<para>
			openserMsgQueueMinorThreshold, openserMsgQueueMajorThreshold,
			openserMsgQueueDepthAlarmStatus, openserMsgQueueDepthMinorAlarm,
			openserMsgQueueDepthMajorAlarm, openserDialogLimitMinorThreshold,
			openserDialogLimitMajorThreshold, openserDialogUsageState,
			openserDialogLimitAlarmStatus, openserDialogLimitMinorAlarm,
			openserDialogLimitMajorAlarm
			</para>
		</section>
		<section>
			<title>SNMP Tables</title>
			<para>
			The SNMPStats module provides several tables, containing more complicated
			data.  The current available tables are:
			</para>

			<para>
			openserSIPPortTable, openserSIPMethodSupportedTable, 
			openserSIPStatusCodesTable, openserSIPRegUserTable, openserSIPContactTable,
			openserSIPRegUserLookupTable
			</para>
		</section>
		<section>
			<title>Alarm Monitoring</title>
			<para>
			If enabled, the SNMPStats module will monitor for alarm conditions. 
			Currently, there are two alarm types defined.  
			</para>
			
			<orderedlist numeration="arabic">
			<listitem>
				<para>
				The number of active dialogs has passed a minor or major threshold.
				The idea is that a network operation centre can be made aware that 
				their SIP servers may be overloaded, without having to explicitly
				check for this condition.
				</para>
				<para>
				If a minor or major condition has occured, then a 
				openserDialogLimitMinorEvent trap or a 
				openserDialogLimitMajorEvent trap will be generated, 
				respectively. The minor and major thresholds are
				described in the parameters section below.
				</para>
			</listitem>
			<listitem>
				<para>
				The number of bytes waiting to be consumed across all of OpenSERs
				listening ports has passed a minor or major threshold.  The idea is
				that a network operation centre can be made aware that a machine 
				hosting a SIP server may be entering a degraded state, and to 
				investigate why this is so. 
				</para>
				<para>
				If the number of bytes to be consumed passes a minor or major 
				threshold, then a openserMsgQueueDepthMinorEvent or 
				openserMsgQueueDepthMajorEvent trap will be sent out, respectively.
				</para>
			</listitem>

			</orderedlist>
			<para>
			Full details of these traps can be found in the distributions OPENSER-MIB
			file.  
			</para>
		</section>
	</section>

	
	<section>
	<title>How it works</title>

	<section>
	<title>How the SNMPStats module gets its data</title>
	<para>
	The SNMPStats module uses OpenSERs internal statistic framework to collect most of its
	data. However, there are two exceptions.  
	<orderedlist>
		<listitem>
			<para>
			The openserSIPRegUserTable and openserSIPContactTable rely on the usrloc 
			modules	callback system.  Specifically, the SNMPStats module will receive 
			callbacks whenever a user/contact is added to the system.
			</para>
		</listitem>
		<listitem>
			<para>
			The SNMPStats modules openserSIPMsgQueueDepthMinorEvent and 
			openserSIPMsgQueueDepthMajorEvent alarms rely on the OpenSER core to find out
			what interfaces, ports, and transports OpenSER is listening on.  However,
			the module will actually query the proc file system to find out the number
			of bytes waiting to be consumed.  (Currently, this will only work on systems
			providing the proc file system).
			</para>
		</listitem>
	</orderedlist> 
	</para>
	</section>
	<section>
	<title>How data is moved from the SNMPStats module to a NOC</title>
	<para>
	We have now explained how the SNMPStats module gathers its data. We still have not
	explained how it exports this data to a NOC (Network Operations Centre), or
	administrator.
	</para>
	<para>
	The SNMPStats module expects to connect to a <emphasis>Master Agent</emphasis>.  This
	would be a NetSNMP daemon running either on the same system as the OpenSER instance, or 
	on another system.  (Communication can take place over TCP, so there is no restriction
	that this daemon need be on the same system as OpenSER).
	</para>
	<para>
	If the master agent is unavailable when OpenSER first starts up, the SNMPStats module will
	continue to run.  However, you will not be able to query it.  Thankfully, the SNMPStats
	module continually looks for its master agent.  So even if the master agent is started late, 
	or if the link to the SNMPStats module is severed due to a temporary hardware failure
	or crashed and restarted master agent, the link will eventually be re-established.  No
	data should be lost, and querying can begin again. 
	</para>
	<para>
	To request for this data, you will need to query the master agent.  The master agent will
	then redirect the request to the SNMPStats module, which will respond to the master agent, 
	which will in turn respond to your request.  
	</para>
	</section>

	</section>

	<section>
	<title>Dependencies</title>
	<section>
		<title>&ser; Modules</title>
		<para>
		The SNMPStats module provides a plethora of statistics, some of which are collected
		by other modules.  If the dependent modules are not loaded then those specific 
		statistics will still be returned, but with zeroed values.  All other statistics will
		continue to function normally.  This means that the SNMPStats module has no  
		<emphasis>hard/mandatory</emphasis> dependencies on other modules.  There are however,
		<emphasis>soft</emphasis> dependencies, as follows:
		<itemizedlist>
		
		<listitem>
		<para>
		<emphasis>usrloc</emphasis> - all scalars and tables relating to users and contacts are
		dependent on the usrloc module.  If the module is not loaded, the respective tables
		will be empty. 
		</para>
		</listitem>
		
		<listitem>
		<para>
		<emphasis>dialog</emphasis> - all scalars relating to the number of dialogs are 
		dependent on the presence of the dialog module.  Furthermore, if the module is 
		not loaded, then the openserDialogLimitMinorEvent, and openserDialogLimitMajorEvent
		alarm will be disabled. 
		</para>
		</listitem>
		
		</itemizedlist>
		The contents of the openserSIPMethodSupportedTable change depending on which modules
		are loaded.  
		</para>
	</section>
	<section>
	<title>External Libraries or Applications</title>
	<para>
	The following libraries or applications must be installed before running
	&ser; with this module loaded:
		<itemizedlist>
		<listitem>
		<para>
			<emphasis>NetSNMP v5.3 or greater</emphasis> - NetSNMP must be around 
			at the time of compilation.  Furthermore, there are several shared objects
			that must be loadable at the time SNMPStats is loaded.  This means that
			NetSNMP must be installed (but not necessarily running) on the system that
			has loaded the SNMPStats module.  (Details can be found in the compilation 
			section	below).
		</para>
		</listitem>
		</itemizedlist>
	</para>
	</section>
	</section>
	<section>
	<title>Exported Parameters</title>
	<section>
		<title><varname>sipEntityType</varname> (String) </title>

		<para>
		This parameter describes the entity type for this OpenSER instance,
		and will be used in determining what is returned for the
		openserSIPEntityType scalar. Valid parameters are:
		</para>

		<para>
		<emphasis>
		registrarServer, redirectServer, proxyServer, userAgent, other
		</emphasis>
		</para>

		<example>
		<title>Setting the <varname>sipEntityType</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("snmpstats", "sipEntityType", "registrarServer")
modparam("snmpstats", "sipEntityType", "proxyServer")
...
		</programlisting>
		</example>

		<para>
		Note that as the above example shows, you can define this parameter more
		than once.  This is of course because a given OpenSER instance can take on
		more than one role.
		</para>
	</section>

	<section>
		<title><varname>MsgQueueMinorThreshold</varname> (Integer)</title>

		<para>
		The SNMPStats module monitors the number of bytes waiting to be consumed by 
		OpenSER.  If the number of bytes waiting to be consumed exceeds a minor
		threshold, the SNMPStats module will send out an openserMsgQueueDepthMinorEvent
		trap to signal that an alarm condition has occured.  The minor threshold is set
		with the MsgQueueMinorThreshold parameter.  
		</para>

		<example>
		<title>Setting the <varname>MsgQueueMinorThreshold</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("snmpstats", "MsgQueueMinorThreshold", 2000)
...
		</programlisting>
		</example>

		<para>
		If this parameter is not set, then there will be no minor alarm monitoring.
		</para>
	</section>
	
	<section>
		<title><varname>MsgQueueMajorThreshold</varname> (Integer)</title>

		<para>
		The SNMPStats module monitors the number of bytes waiting to be consumed by 
		OpenSER.  If the number of bytes waiting to be consumed exceeds a major
		threshold, the SNMPStats module will send out an openserMsgQueueDepthMajorEvent
		trap to signal that an alarm condition has occured.  The major threshold is set
		with the MsgQueueMajorThreshold parameter.  
		</para>

		<example>
		<title>Setting the <varname>MsgQueueMajorThreshold</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("snmpstats", "MsgQueueMajorThreshold", 5000)
...
		</programlisting>
		</example>

		<para>
		If this parameter is not set, then there will be no major alarm monitoring.
		</para>
	</section>

	<section>
		<title><varname>dlg_minor_threshold</varname> (Integer)</title>

		<para>
		The SNMPStats module monitors the number of active dialogs.  If the number of
		active dialogs exceeds a minor threshold, the SNMPStats module will send out 
		an openserDialogLimitMinorEvent trap to signal that an alarm condition has 
		occured.  The minor threshold is set with the dlg_minor_threshold parameter.  
		</para>

		<example>
		<title>Setting the <varname>dlg_minor_threshold</varname> parameter</title>
		<programlisting format="linespecific">
...
  modparam("snmpstats", "dlg_minor_threshold", 500)
...
		</programlisting>
		</example>

		<para>
		If this parameter is not set, then there will be no minor alarm monitoring.
		</para>
	</section>

	<section>
		<title><varname>dlg_major_threshold</varname> (Integer)</title>

		<para>
		The SNMPStats module monitors the number of active dialogs.  If the number of
		active dialogs exceeds a major threshold, the SNMPStats module will send out 
		an openserDialogLimitMajorEvent trap to signal that an alarm condition has 
		occured.  The major threshold is set with the dlg_major_threshold parameter.  
		</para>

		<example>
		<title>Setting the <varname>dlg_major_threshold</varname> parameter</title>
		<programlisting format="linespecific">
...
  modparam("snmpstats", "dlg_major_threshold", 750)
...
		</programlisting>
		</example>

		<para>
		If this parameter is not set, then there will be no major alarm monitoring.
		</para>
	</section>

	<section>
		<title><varname>snmpgetPath</varname> (String)</title>

		<para>
		The SNMPStats module provides the openserSIPServiceStartTime scalar.
		This scalar requires the SNMPStats module to perform a snmpget query
		to the master agent.  You can use this parameter to set the path to 
		your instance of NetSNMP's snmpget program.  
		</para>

		<para>
		<emphasis>
			Default value is <quote>/usr/local/bin/</quote>.
		</emphasis>
		</para>

		<example>
		<title>Setting the <varname>snmpgetPath</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("snmpstats", "snmpgetPath",     "/my/custom/path/")
...
		</programlisting>
		</example>
	</section>
	
	<section>
		<title><varname>snmpCommunity</varname> (String)</title>

		<para>
		The SNMPStats module provides the openserSIPServiceStartTime scalar.
		This scalar requires the SNMPStats module to perform a snmpget query
		to the master agent.  If you have defined a custom community string
		for the snmp daemon, you need to specify it with this parameter.  
		</para>

		<para>
		<emphasis>
			Default value is <quote>public</quote>.
		</emphasis>
		</para>

		<example>
		<title>Setting the <varname>snmpCommunity</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("snmpstats", "snmpCommunity", "customCommunityString")
...
		</programlisting>
		</example>
	</section>

	</section>
	<section>
	<title>Exported Functions</title>
		<para>
		Currently, there are no exported functions.
		</para>
	</section>
	<section>
	<title>Installation & Running</title>
	<para>
	There are several things that need to be done to get the SNMPStats module
	compiled and up and running.
	</para>

	<section>
	<title>
	Compiling the SNMPStats Module
	</title>
	<para>
	In order for the SNMPStats module to compile, you will need at least version
	5.3 of the NetSNMP source code.  The source can be found at:

	<programlisting format="linespecific">
    http://net-snmp.sourceforge.net/ 
	</programlisting>

	For the specifics of installing NetSNMP, please see the INSTALL document in the
	root of the NetSNMP source package.  
	</para>

	<para>
	The SNMPStats modules makefile requires that the NetSNMP script
	"net-snmp-config" can run.  At a minimum, running "net-snmp-config --agent-libs"
	from the OpenSER source directory should return something similar to: 

	<programlisting format="linespecific">
    -L/usr/local/lib -lnetsnmpmibs -lnetsnmpagent -lnetsnmphelpers -lnetsnmp
	</programlisting>

	The specifics of what is returned depends on how the system was configured. If
	your NetSNMP installation was installed from an RPM (or another packaged
	version), then there is a good chance that net-snmp-config will return
	something unecessarily longer.  It is highly recommended you install NetSNMP
	from source to avoid bringing in excessive dependencies to the SNMPStats
	module.
	</para>
	</section>
	
	<section>
	<title>
	Configuring NetSNMP to allow connections from the SNMPStats module.
	</title>
	<para>
	The SNMPStats module will communicate with the NetSNMP Master Agent.  This 
	communication happens over a protocol known as AgentX. This means that NetSNMP
	must have been compiled with AgentX support.  This will always be the case when
	you are compiling from source unless you explicitly removed AgentX support with
	./configure.  
	</para>

	<para>
	After AgentX support has been compiled into NetSNMP, its configuration file needs
	to be changed to turn on AgentX support.  The exact location of the configuration 
	file (snmpd.conf) may vary depending on your system.  On my system, it is located in:
 
	<programlisting format="linespecific">
    /usr/local/share/snmp/snmpd.conf.
    	</programlisting>

	At the very end of the file add the following line:

	<programlisting format="linespecific">
    master agentx
	</programlisting>

	The line tells NetSNMP to act as an AgentX master agent, so that it can accept
	connections from sub-agents such as the SNMPStats module.  
	</para>

	<para>
	There is still one last step.  Even though we have compiled and configured NetSNMP
	to have AgentX support, we still need to tell the daemon which interface and 
	port to listen to for AgentX connections. This is done when the daemon is started
	as follows:

	<programlisting format="linespecific">
    snmpd -x mySystemName:PortNumber
	</programlisting>

	On my system, I start the NetSNMP daemon with:

	<programlisting format="linespecific">
    snmpd -x localhost:705
	</programlisting>

	This tells NetSNMP to act as a master agent, listening on the localhost
	interface at port 705.  
	</para>
	</section>
	
	<section>
	<title>
	Configuring the SNMPStats module for communication with a Master Agent
	</title>
	<para>
	The previous section explained how to set up a NetSNMP master agent to accept
	AgentX connections.  We now need to tell the SNMPStats module how to communicate
	with this master agent.  This is done by giving the SNMPStats module its own
	NetSNMP configuration file.  The file must be named snmpstats.conf, and must be
	in the same folder as the snmpd.conf file that was configured above. On my 
	system this would be:

	<programlisting format="linespecific">
    /usr/local/share/snmp/snmpstats.conf
	</programlisting>

	The default configuration file included with the distribution can be used, and
	contains the following:

	<programlisting format="linespecific">
    agentXSocket tcp:localhost:705
	</programlisting>

	The above line tells the SNMPStats module to register with the master agent on
	the localhost, port 705.  The parameters should match up with the snmpd process.
	Note that the master agent (snmpd) does not need to be present on the same
	machine as OpenSER.  localhost could be replaced with any other machine. 
	</para>
	</section>
	
	<section>
	<title>
	Testing for a proper Configuration
	</title>
	<para>
	As a quick test to make sure that the SNMPStats module sub-agent can succesfully
	connect to the NetSNMP Master agent, start snmpd with the following:

	<programlisting format="linespecific">
    snmpd -f -Dagentx -x localhost:705 2>&1 | less
	</programlisting>

	You should see something similar to the following:

	<programlisting format="linespecific">
    No log handling enabled - turning on stderr logging
    registered debug token agentx, 1
    ...
    Turning on AgentX master support.
    agentx/master: initializing...
    agentx/master: initializing...   DONE
    NET-SNMP version 5.3.1
	</programlisting>

	Now, start up OpenSER in another window.  In the snmpd window, you should see a
	bunch of:

	<programlisting format="linespecific">
    agentx/master: handle pdu (req=0x2c58ebd4,trans=0x0,sess=0x0)
    agentx/master: open 0x81137c0
    agentx/master: opened 0x814bbe0 = 6 with flags = a0
    agentx/master: send response, stat 0 (req=0x2c58ebd4,trans=0x0,sess=0x0)
    agentx_build: packet built okay
	</programlisting>

	The messages beginning with "agentx" are debug messages stating that something is happening
	with an AgentX sub-agent, appearing because of the -Dagentx snmpd switch.  The large number
	of debug messages appear at startup as the SNMPStats module registers all of its scalars
	and tables with the Master Agent.  If you receive these messages, then SNMPStats module
	and NetSNMP daemon have both been configured correctly.
	</para>
	</section>

	</section>
</chapter>

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