Transport tweaks
****************


Custom request timeout
======================

Send SNMP GET request using the following options:

* with SNMPv2c, community 'public'

* over IPv4/UDP

* to an Agent at demo.snmplabs.com:161

* for an OID in string form

* use custom timeout and request retries values

Transport timing settings (maximum number of request retries and
individual request timeout in seconds) can be set on a per-target
basis as explained by the code that follows.

Keep in mind that while timeout value can be specified in fractions of
a second, default pysnmp timer resolution is quite low (about 0.5 sec)
so there's no much point in using timeouts which is not a multiple of
0.5 Internal timer can be programmatically adjusted to finer
resolution if needed.

If retries value is set to 0, pysnmp will issue a single request. Even
if no response arrives, there will be no retry. Likewise, retries=1
means one initial request plus one retry.

Functionally similar to:

   $ snmpget -v1 -c public -t 2 -r 0 demo.snmplabs.com 1.3.6.1.2.1.1.1.0

   from pysnmp.hlapi import *

   errorIndication, errorStatus, errorIndex, varBinds = next(
       getCmd(SnmpEngine(),
              CommunityData('public'),
              UdpTransportTarget(
                  ('demo.snmplabs.com', 161), timeout=2.0, retries=0
              ),
              ContextData(),
              ObjectType(ObjectIdentity('1.3.6.1.2.1.1.1.0')))
   )

   if errorIndication:
       print(errorIndication)
   elif errorStatus:
       print('%s at %s' % (errorStatus.prettyPrint(),
                           errorIndex and varBinds[int(errorIndex) - 1][0] or '?'))
   else:
       for varBind in varBinds:
           print(' = '.join([x.prettyPrint() for x in varBind]))

"Download" script.


GET over IPv6
=============

Send SNMP GET request using the following options:

* with SNMPv3 with user 'usr-md5-des', MD5 auth and DES privacy
  protocols

* over IPv6/UDP

* to an Agent at [::1]:161

* for three OIDs in string form

Functionally similar to:

   $ snmpget -v3 -l authPriv -u usr-md5-des -A authkey1 -X privkey1 udp6:[::1]:161 1.3.6.1.2.1.1.1.0 1.3.6.1.2.1.1.2.0 1.3.6.1.2.1.1.3.0

   from pysnmp.hlapi import *

   errorIndication, errorStatus, errorIndex, varBinds = next(
       getCmd(SnmpEngine(),
              UsmUserData('usr-md5-des', 'authkey1', 'privkey1'),
              Udp6TransportTarget(('::1', 161)),
              ContextData(),
              ObjectType(ObjectIdentity('1.3.6.1.2.1.1.1.0')),
              ObjectType(ObjectIdentity('1.3.6.1.2.1.1.2.0')),
              ObjectType(ObjectIdentity('1.3.6.1.2.1.1.3.0')))
   )

   if errorIndication:
       print(errorIndication)
   elif errorStatus:
       print('%s at %s' % (errorStatus.prettyPrint(),
                           errorIndex and varBinds[int(errorIndex) - 1][0] or '?'))
   else:
       for varBind in varBinds:
           print(' = '.join([x.prettyPrint() for x in varBind]))

"Download" script.

See also: library reference.
