Thank you for all the answers!
I figured out that it was my mistake - if I unpack MIBs into /usr/share/snmp/mibs directory, then e.g. mbrowse loads them appropriately.
The truth is, that as a part of my msc thesis I must write module which retrieves counters of queued packets/bytes in best-effort queues for all interfaces. Both IReasoning MIB browser and MBrowse sees OID: jnxCosQstatQedPkts (.1.3.6.1.4.1.2636.3.15.4.1.3) (it's under the one suggested by conty). It is marked as leaf and it has type counter(64) so it suggests (at least for me) that it is single-value. Apart from this it it obvious that it must contain information for multiple queues for multiple interfaces....
Ok, so when i walk this OID there is:
snmpwalk -m JUNIPER-COS-MIB -v 2c -c private myrouter .1.3.6.1.4.1.2636.3.15.4.1.3
JUNIPER-COS-MIB::jnxCosQstatQedPkts.151.0 = Counter64: 279809
JUNIPER-COS-MIB::jnxCosQstatQedPkts.151.1 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.151.2 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.151.3 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.151.4 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.151.5 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.151.6 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.151.7 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.507.0 = Counter64: 874176
JUNIPER-COS-MIB::jnxCosQstatQedPkts.507.1 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.507.2 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.507.3 = Counter64: 1778836
JUNIPER-COS-MIB::jnxCosQstatQedPkts.507.4 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.507.5 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.507.6 = Counter64: 0
JUNIPER-COS-MIB::jnxCosQstatQedPkts.507.7 = Counter64: 0
and values for *.151.0 and *.507.0 are the same as I can retrieve using CLI:
lab@187# run show interfaces queue ge-0/0/0
Physical interface: ge-0/0/0, Enabled, Physical link is Up
Interface index: 133, SNMP ifIndex: 151
Description: MGMT INTERFACE - DO NOT DELETE
Forwarding classes: 8 supported, 4 in use
Egress queues: 8 supported, 4 in use
Queue: 0, Forwarding classes: best-effort
Queued:
Packets : 279844 1 pps
lab@187# run show interfaces queue ge-0/0/1
Physical interface: ge-0/0/1, Enabled, Physical link is Up
Interface index: 134, SNMP ifIndex: 507
Forwarding classes: 8 supported, 4 in use
Egress queues: 8 supported, 4 in use
Queue: 0, Forwarding classes: best-effort
Queued:
Packets : 874176 0 pps
But I don't know if there is any "generic" method to retrieve OID numbers for best-effort queued packets for all router's interfaces. (it is something I would put in a documentation for my soft).
Thank you in advance.