Zabbix and count of records in SNMP tree

[bion]

Hello all.

We have a little problem: how to count the number of MAC addresses on the switch port. For example, on port 13 discovered 2 MAC addresses. By means snmpwalker I can see it:

alex@ubuntu:~$ snmpwalk -c public -v 2c 192.168.1.1 .atPhysAddress.13
RFC1213-MIB::atPhysAddress.13.1.192.168.1.2 = Hex-STRING: 00 21 9B D7 C6 31 
RFC1213-MIB::atPhysAddress.13.1.192.168.1.128 = Hex-STRING: 00 0C 29 84 7A E5

Can we count record in snmp tree (in our case number=2) and monitored this value by means Zabbix?

Thanks to all.