I'm trying to use low-level discovery to walk the OID tree for an F5 BIG-IP load balancer and have it discover all the resource pools. Here's sample output from snmpwalk:

$ snmpwalk -v2c -c public 192.168.20.16 F5-BIGIP-LOCAL-MIB::ltmPoolName
F5-BIGIP-LOCAL-MIB::ltmPoolName."client-sites" = STRING: client-sites
F5-BIGIP-LOCAL-MIB::ltmPoolName."external_webservices_pool" = STRING: external_webservices_pool

As you can see, rather than a specific SNMP index, each of these items is a string. This is more of a problem if you look at the raw OIDs:

$ snmpwalk -On -v2c -c public 192.168.20.16 F5-BIGIP-LOCAL-MIB::ltmPoolName.\"client-sites\"
.1.3.6.1.4.1.3375.2.2.5.1.2.1.1.12.99.108.105.101.110.116.45.115.105.116.101.115 = STRING: client-sites
$ snmpwalk -On -v2c -c public 192.168.20.16 F5-BIGIP-LOCAL-MIB::ltmPoolName.\"external_webservices_pool\"
.1.3.6.1.4.1.3375.2.2.5.1.2.1.1.25.101.120.116.101.114.110.97.108.95.119.101.98.115.101.114.118.105.99.101.115.95.112.111.111.108 = STRING: external_webservices_pool

Zabbix appears to expect a single index at the end of the tree, but that doesn't work with this type of mib tree in which the values are just arbitrary strings.