Nagios Plugins

Hi, when I create a service to check_snmp values, if the snmp agent returns a enumeration value with the following declaration

rttState OBJECT-TYPE
SYNTAX INTEGER {
unknown(0),
running(1),
stopped(2)
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The currently configured status of an instance."
::= { rttEntry 3 }

if the command doesn't include a warning or critical threshold,

./check_snmp -p 161 -H 10.36.0.50 -o enterprises.40312.1.1.1.3.1 -C public -P 2c -l "rttState-Instance1" -m /usr/share/snmp/mibs/RTT-MIB.txt

the check_snmp command returns
rttState-Instance1 OK - running(1) |

However, if the warning or critical threshold is declared, such as

./check_snmp -p 161 -H 10.36.0.50 -o enterprises.40312.1.1.1.3.1 -C public -P 2c -l "rttState-Instance1" -m /usr/share/snmp/mibs/RTT-MIB.txt -w 1:2

it would return

rttState-Instance1 OK - 1 | RTT-MIB::rttState.1=1

It doesn't display the enumerated value.