Many thanks Morten for the answer. Now my NAV installation includes graphs for broadcast & multicast packets per second.
I modified the following files:
/usr/share/nav/templates/ipdevinfo/port-details.html /usr/share/pyshared/nav/ipdevpoll/plugins/statports.py /usr/share/pyshared/nav/web/ipdevinfo/views.py /usr/share/pyshared/nav/web/ipdevinfo/utils.py
to include the references to the new counters.
Furthermore I added the rows regarding the new oid objects on snmpoid db table.
As a reference regarding Enterasys hardware (in this case matrix N7 firmware version 06.12.08.0003), I noticed that if you make an snmp query for the ifOutMulticastPkts counter, the switch incorrectly answers with the ifOutBroadcastPkts value, instead ifHCOutMulticastPkts is fine, so I implemented in statports.py the same logic as HC_OCTET_COUNTERS (= choose HC if available).
Alex