Add option to walk

[yvan34]

Hello,
I have a MIB that use the char "_" in.
To walk, it's needed to add option to snmpwalk --> -Pu (this option is allow "_" in MIB)
In zabbix, when i use this MIB, i got the same error than snmpwalk when i don't use option -Pu.

########### Sample
The mib is for Zyxel GPON OTL1404

The command without option Pu :
snmpwalk -v3 -a SHA -A mypass -x DES -X mypass -l authPriv -u myuser MYHOST ZYXEL-olt1404-MIB::ifGponPortName
The result :
Expected "(" (_): At line 7507 in /usr/share/snmp/mibs/OLT1404.mib
Should be ACCESS (as): At line 7507 in /usr/share/snmp/mibs/OLT1404.mib
Bad parse of OBJECT-TYPE: At line 7507 in /usr/share/snmp/mibs/OLT1404.mib
ZYXEL-olt1404-MIB::ifGponPortName: Unknown Object Identifier

The command with option Pu :
snmpwalk -Pu -v3 -a SHA -A mypass -x DES -X mypass -l authPriv -u myuser MYHOST ZYXEL-olt1404-MIB::ifGponPortName
The result :
ZYXEL-olt1404-MIB::ifGponPortName.1 = STRING: "pon-1"
ZYXEL-olt1404-MIB::ifGponPortName.2 = STRING: "pon-2"
ZYXEL-olt1404-MIB::ifGponPortName.3 = STRING: "pon-3"
ZYXEL-olt1404-MIB::ifGponPortName.4 = STRING: "pon-4"
ZYXEL-olt1404-MIB::ifGponPortName.5 = STRING: "eth-1"
ZYXEL-olt1404-MIB::ifGponPortName.6 = STRING: "eth-2"

In Zabbix log, i found exactly the same error massage when i do not use the option Pu
################ END Sample

My question : Where can i put this option in Zabbix for walking this MIB ?

Thanks for help