$Revision: 1722 $ $Date: 2007-03-01 14:10:43 +0200 (Thu, 01 Mar 2007) $

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.

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: 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 There are also scalars associated with alarms. They are as follows: openserMsgQueueMinorThreshold, openserMsgQueueMajorThreshold, openserMsgQueueDepthAlarmStatus, openserMsgQueueDepthMinorAlarm, openserMsgQueueDepthMajorAlarm, openserDialogLimitMinorThreshold, openserDialogLimitMajorThreshold, openserDialogUsageState, openserDialogLimitAlarmStatus, openserDialogLimitMinorAlarm, openserDialogLimitMajorAlarm

The SNMPStats module provides several tables, containing more complicated data. The current available tables are: openserSIPPortTable, openserSIPMethodSupportedTable, openserSIPStatusCodesTable, openserSIPRegUserTable, openserSIPContactTable, openserSIPRegUserLookupTable

If enabled, the SNMPStats module will monitor for alarm conditions. Currently, there are two alarm types defined. 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. 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. 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. 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. Full details of these traps can be found in the distributions OPENSER-MIB file.

The SNMPStats module uses OpenSERs internal statistic framework to collect most of its data. However, there are two exceptions. 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. 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).

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. The SNMPStats module expects to connect to a Master Agent. 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). 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. 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.

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 hard/mandatory dependencies on other modules. There are however, soft dependencies, as follows: usrloc - 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. dialog - 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. The contents of the openserSIPMethodSupportedTable change depending on which modules are loaded.

The following libraries or applications must be installed before running &ser; with this module loaded: NetSNMP v5.3 or greater - 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).

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: registrarServer, redirectServer, proxyServer, userAgent, other ... modparam("snmpstats", "sipEntityType", "registrarServer") modparam("snmpstats", "sipEntityType", "proxyServer") ... 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.

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. ... modparam("snmpstats", "MsgQueueMinorThreshold", 2000) ... If this parameter is not set, then there will be no minor alarm monitoring.

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. ... modparam("snmpstats", "MsgQueueMajorThreshold", 5000) ... If this parameter is not set, then there will be no major alarm monitoring.

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. ... modparam("snmpstats", "dlg_minor_threshold", 500) ... If this parameter is not set, then there will be no minor alarm monitoring.

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. ... modparam("snmpstats", "dlg_major_threshold", 750) ... If this parameter is not set, then there will be no major alarm monitoring.

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. Default value is /usr/local/bin/. ... modparam("snmpstats", "snmpgetPath", "/my/custom/path/") ...

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. Default value is public. ... modparam("snmpstats", "snmpCommunity", "customCommunityString") ...

Currently, there are no exported functions.

There are several things that need to be done to get the SNMPStats module compiled and up and running.

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: http://net-snmp.sourceforge.net/ For the specifics of installing NetSNMP, please see the INSTALL document in the root of the NetSNMP source package. 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: -L/usr/local/lib -lnetsnmpmibs -lnetsnmpagent -lnetsnmphelpers -lnetsnmp 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.

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. 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: /usr/local/share/snmp/snmpd.conf. At the very end of the file add the following line: master agentx 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. 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: snmpd -x mySystemName:PortNumber On my system, I start the NetSNMP daemon with: snmpd -x localhost:705 This tells NetSNMP to act as a master agent, listening on the localhost interface at port 705.

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: /usr/local/share/snmp/snmpstats.conf The default configuration file included with the distribution can be used, and contains the following: agentXSocket tcp:localhost:705 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.

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: snmpd -f -Dagentx -x localhost:705 2>&1 | less You should see something similar to the following: 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 Now, start up OpenSER in another window. In the snmpd window, you should see a bunch of: 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 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.