According to RFC4293 it is possible to have per address family counters in interface statistics. Right now the per interface system wide traffic statistics (ipTrafficStats) is not supported by RouterOS at all. in the IP-MIB there are counters in ipIfStatsTable which have double indices:
- ipIfStatsIPVersion: 1 for IPv4 and 2 for IPv6
- ipIfStatsIfIndex: ifIndex of the interface the statistics belong to
IP-MIB is available from here: http://ipmsupport.solarwinds.com/mibs/IP-MIB/raw.aspx
bat:~$ snmpwalk -v 2c -c public some-router 1.3.6.1.2.1.4.31.3.1.33.2 <-- shows IPv6 only traffic
iso.3.6.1.2.1.4.31.3.1.33.2.210 = Counter64: 0
iso.3.6.1.2.1.4.31.3.1.33.2.749 = Counter64: 46320383060949
iso.3.6.1.2.1.4.31.3.1.33.2.1187 = Counter64: 1910005989
bat:~$ snmpget -v 2c -c public some-router ifDescr.210 ifDescr.749 ifDescr.1187
IF-MIB::ifDescr.210 = STRING: BVI2002
IF-MIB::ifDescr.749 = STRING: Bundle-Ether10.2006
IF-MIB::ifDescr.1187 = STRING: GigabitEthernet200/0/0/8
it would be very important to see per address-family counters to plan with resources like CGN/LSN in an ISP.
if it is not possible to support the actual IP-MIB, a vendor-specific implementation in the MIKROTIK-MIB is also an option.