[c-nsp] broken counters on sup720 (not 32bit snmp issue)

[Bas]

Hi,

I've got a 6506/sup720 running 12.2.18SXF4 with some strange behaviour.

One vlan generates about 4Gbit/s traffic, but both snmp and "sh int
vlan xx" report incorrect values.

The rollover point seems to be around 3.5Gbit/s, after that values are
reported to be around 700Mbit/s and up.

before rollover:

mgr-r1#sh int vlan 11 | i minu
 1 minute input rate 3481725000 bits/sec, 299069 packets/sec
 1 minute output rate 151468000 bits/sec, 165552 packets/sec

After rollover:

mgr-r1#sh int vlan 11 | i minu
 1 minute input rate 780017000 bits/sec, 308148 packets/sec
 1 minute output rate 156125000 bits/sec, 172028 packets/sec

Strange enough packets/sec still increments correctly.

Is this a know issue? Is there something I can do about this?

Thanks in advance,

Bas