Cisco :: Find Client IP Connected To VLAN From Catalyst 3600

I would like to get using of course SNMP, list of client IPs connected to VLAN in Cisco Catalyst 3600.So far, I have pseudo-algorithm made by me which obtains those IP addresses, but I am not sure if this is done in right way :

1) Receive all IP addresses from Catalyst using oid 1.3.6.1.2.1.4.20.1.2. I get something like :

IP-MIB::ipAdEntIfIndex.10.10.2.1 = INTEGER: 152
IP-MIB::ipAdEntIfIndex.10.10.2.251 = INTEGER: 152
IP-MIB::ipAdEntIfIndex.10.10.3.251 = INTEGER: 151 and so on.
2) Get ifIndex of VLAN (oid 1.3.6.1.2.1.4.20.1.2.10.10.2.1.<IP_ADDRESS>) for particular IP address from above list :
IP-MIB::ipAdEntIfIndex.10.10.2.1 = INTEGER: 152
IP-MIB::ipAdEntIfIndex.10.10.2.251 = INTEGER: 152
IP-MIB::ipAdEntIfIndex.10.10.3.251 = INTEGER: 151
3) Get VLAN name (oid 1.3.6.1.4.1.9.9.46.1.3.1.1.4.1.<IF_INDEX>) If_index is borrowed from list above :
IP-MIB::ipAdEntNetMask.152 = No Such Instance currently exists at this OID
IP-MIB::ipAdEntNetMask.151 = No Such Instance currently exists at this OID

In the third step I have this problem, that instance can not be found in OID. It is weird, because for about forty IP addresses i can find about their 10 VLAN names to which they are connected.