note 88349 added to function.snmpget

About the "timeout" and "retries" parameters (conveniently not documented): From snmp_api.h (net-snmp): 170 struct snmp_session { 171 /* 172 * Protocol-version independent fields 173 */ 174 long version; 175 int retries; /* Number of retries before timeout. */ 176 long timeout; /* Number of uS until first timeout, then exponential backoff */ The important pieces here are "retries" and "timeout". "retries": this number is the number of retries before timeout. If not specified, this defaults to SNMP_DEFAULT_RETRIES--the C constant; there is no corresponding PHP constant. "timeout": this is the number of MICRO-SECONDS (*not* nano-seconds; the "u" is latin-character shorthand for a lowercase Greek "myu"). If not specified, this defaults to SNMP_DEFAULT_TIMEOUT--the C constant; there is no corresponding PHP constant. From snmp_api.h (net-snmp): 250 #define SNMP_DEFAULT_RETRIES -1 251 #define SNMP_DEFAULT_TIMEOUT -1 Now, if the default values (SNMP_DEFAULT_RETRIES or SNMP_DEFAULT_TIMEOUT) are used, then SNMP defaults the values to--and again, these are internal constants--DEFAULT_RETRIES and DEFAULT_TIMEOUT, respectively. From snmp_api.c (net-snmp): 189 #define DEFAULT_RETRIES 5 190 #define DEFAULT_TIMEOUT 1000000L This means: 1. SNMP tries 1 + 5 times to perform an action. 2. SNMP initially times out after 1 second. After some testing against an agent that does not return a proper error code if an OID is not found, I currently do not believe that "snmpget" only retries 5 times; using the default settings for "snmpget", I've seen the following output from a script that simply performed one snmpget with an IP, community string, and "ifName.1": Performing snmpget... Warning: snmpget(): Error in packet: (noSuchName) There is no such variable name in this MIB. in /root/test.php on line 13 Warning: snmpget(): This name does not exist: in /root/test.php on line 13 [...] [These two warning lines continued essentially forever--at least 10 minutes, which is definitely not worth 5 retries.] However, changing the retries value here had some effect; I am currently not sure why. ---- Server IP: 64.71.164.2 Probable Submitter: 216.158.20.130 ---- Manual Page -- http://www.php.net/manual/en/function.snmpget.php Edit -- https://master.php.net/note/edit/88349 Del: integrated -- https://master.php.net/note/delete/88349/integrated Del: useless -- https://master.php.net/note/delete/88349/useless Del: bad code -- https://master.php.net/note/delete/88349/bad+code Del: spam -- https://master.php.net/note/delete/88349/spam Del: non-english -- https://master.php.net/note/delete/88349/non-english Del: in docs -- https://master.php.net/note/delete/88349/in+docs Del: other reasons-- https://master.php.net/note/delete/88349 Reject -- https://master.php.net/note/reject/88349 Search -- https://master.php.net/manage/user-notes.php