# 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.