Difference between revisions of "Plugin:SNMP"
(Relicensed to MIT license.)
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| Copyright='''' Florian Forster
Latest revision as of 09:51, 21 May 2015
|Callbacks:||config, init, read, shutdown|
|Copyright:||2007–2012 Florian Forster|
|List of Plugins|
The SNMP plugin uses the Net-SNMP library to read values from network devices using the Simple Network Management Protocol (SNMP). SNMP is a widespread standard to provide management data from devices such as switches, routers, rack monitoring systems, uninterruptible power supplies (UPS), etc. While theoretically possible, collecting values from other computers via this protocol is discouraged in favor of collectd's own protocol, implemented by the Network plugin.
This plugin is a generic plugin, i.e. it cannot work without configuration, because there is no reasonable default behavior. Please read the Plugin snmp section of the collectd.conf(5) manual page for an in-depth description of the plugin's configuration. The majority of documentation for this plugin has been moved to the collectd-snmp(5) manual page.
- → See: Plugin:SNMP/Config
LoadPlugin snmp # ... <Plugin snmp> Type "voltage" Table false Instance "input_line1" Scale 0.1 Values "SNMPv2-SMI::enterprises.6050.5.4.1.1.2.1" Type "users" Table false Instance "" Shift -1 Values "HOST-RESOURCES-MIB::hrSystemNumUsers.0" Type "if_octets" Table true Instance "IF-MIB::ifDescr" Values "IF-MIB::ifInOctets" "IF-MIB::ifOutOctets" <Host "some.switch.mydomain.org"> Address "192.168.0.2" Version 1 Community "community_string" Collect "std_traffic" Interval 120 </Host> <Host "some.server.mydomain.org"> Address "192.168.0.42" Version 2 Community "another_string" Collect "std_traffic" "hr_users" </Host> <Host "some.ups.mydomain.org"> Address "192.168.0.3" Version 1 Community "more_communities" Collect "powerplus_voltge_input" Interval 300 </Host> </Plugin>
Data center power supply
The following graphs are from a device monitoring a data center's power supply. The graphs show voltage, current, power and for a main line or fuse.
Unique instance names
You should be careful with the OID you use for the Instance parameter: For example
IF-MIB::ifDescr is often not sufficiently unique, using
IF-MIB::ifName may be better. In some of the provided examples this will bite you with certain devices (for example switches by Cisco).
Another problem may arise from instance names being too long. Currently there is a 63 character limit on instance names, see Naming schema. If two strings only differ after the 63rd character, the resulting name will not be unique.
Maximum number of hosts
While collectd and the SNMP plugin don't have any limitation on the number of hosts you can configure, the library used by the SNMP plugin, libnetsnmp, uses the select(2) system call. This system call uses a fixed-size bitfield to hold file descriptors. On many systems this limits the number of hosts you can query with the SNMP plugin to 1024 (for example when using the GNU libc).
To solve this issue, the netsnmp library must be changed. A solution would be to switch to the poll(2) system call which doesn't have a static limit on the largest file descriptor it can handle.