debian net-snmp IF-MIB::ifNumber problem

Hello

I am trying to monitor a Linux host running Debian sarge with 5.1.2-6.2
net-snmp package installed. This acts as a router for many vpn
connections :
ifconfig -a | grep "Link encap" | wc -l
outputs 65.

Querying from another host the snmp daemon:
snmpwalk -Cc -c public -v 2c host-LinuxDebian IF-MIB::ifNumber
outputs: IF-MIB::ifNumber.0 = INTEGER: 63
while the same command querying a Cisco Catalist Switch responded
corectly.

Since I am somekind of newbie in snmp internals, I suspect me doing
something wrong. Still snmpd.conf, except that I specified the public
community is empty.

So I want to know if there is a problem with net-snmp package, or I am
wrong.

Thank you for any help/advice.
L.