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Traffic and status of network interfaces using 32 bit counters

Distribution: official part of Check_MK
License: GPL
Supported Agents: SNMP

This check monitors the operational status, link speed, traffic, packet counts, discards and errors of network interfaces by using the information provided by the standard SNMP MIB .1.3.6.1.2.1.2.2 (IF-MIB::ifTable). This MIB is usually supported by all SNMP devices, such as routers, switches, firewalls and even operating systems such as Windows and Linux.

Depending on the check parameters this check can go WARN or CRIT when the port status changes (i.e. is down), when the link speed changes (e.g. a port expected to be set to 1GBit/s operates only at 100MBit/s), when the absolute or procentual traffic of a port exceeds certain levels or if the rate of errors or discards exceeds configurable limits.

As of Check_MK version 1.1.9i1 this check supports averaging the in- and outgoing traffic over a configurable range of time by using an exponentially weighted moving average - just as Linux does for the CPU load averages. The averaging can be configured on a per host and per port base. This is done by adding a key "average" to the parameter dictionary with the number of minutes that the average should cover as its key. Port with averaging turned on output two additional performance values: the averaged traffic in bytes. If you have configured traffic levels, then those levels are applied to the averaged values.

Please note: if your devices supports SNMP v2c you rather should add them to bulkwalk_hosts and use the check if64. That is almost identical to if, but support 64-Bit counters and ifAlias.

Item

There are three allowed ways to specify a port: 1: the last component of the SNMP OID number (as string), the ifDescr of the port or the ifAlias of the port. If you are using the alias, you have to make sure that it is unique by configuring useful aliases in the switch. Check_MK does not check for uniqueness.

Discovery

The inventory creates one service for each port that fulfills configurable conditions. Per default these are ports which are currently found up and are of types 6 (ethernetCsmacd), 32 (frameRelay) or 117 (gigabitEthernet).

Grouping: In some situations you do not want to monitor a single interface but a group of interfaces that together form a pool. The if check supports such pools by defining groups. You can specifiy the members of a group by their port type and the item name(s) of the single interfaces. The data of all members is accumulated and put together in a single grouped interface service.

You can specify the groups with the ruleset if_groups. Groups are defined as list of dictionaries.

The keys are:

"name": String. Name of the group within the service description

"iftype": Integer. Interface port type as integer

"include_items": List of Strings. Interface item name. This name depends on further settings like if_inventory_uses_alias or if_inventory_uses_description

"single"(optional): Bool. Interfaces in this group do not show up as single service if "single" is set to True (Default: False)

For example: if_groups = (["name" : "Group WLAN", "iftype" : 6, "single" : True], ["lan"], ALL_HOSTS )