Description

On QFX5120 running Junos, SNMP queries to dot3OutPauseFrames and dot3InPauseFrames return 0 even when pause frames are observed via CLI under MAC Priority Flow Control Statistics

 

In contrast, QFX5130 running Junos EVO correctly reports these counters through SNMP, indicating a possible implementation gap or bug in SNMP MIB support on Junos.

 

Symptoms

Output from Junos switch:

 

user@switch> show interfaces <interface> extensive | grep "SNMP|^ {2,}(MAC Prio|Priority :)"

Interface index: <ID>, SNMP ifIndex: 513 Generation: <value>

Interface flags: SNMP-Traps Internal: 0x4000

MAC Priority Flow Control Statistics:

Priority : 0 0 0

Priority : 1 0 0

Priority : 2 0 0

Priority : 3 0 0

Priority : 4 0 0

Priority : 5 0 0

Priority : 6 0 8310 <----- (Pause frames observed)

Priority : 7 0 0

 

user@switch> show snmp mib get 1.3.6.1.2.1.10.7.10.1.4.513

dot3OutPauseFrames.513 = 0

 

Output from Junos EVO switch:

 

user@switch> show interfaces <interface> extensive | grep "SNMP|^ {2,}(MAC Prio|Priority :)"

Interface index: <ID>, SNMP ifIndex: 669, Generation: <value>

Interface flags: SNMP-Traps

MAC Priority Flow Control Statistics:

Priority : 0 0 0

Priority : 1 0 0

Priority : 2 0 0

Priority : 3 0 0

Priority : 4 0 0

Priority : 5 0 0

Priority : 6 506066 0 <----- (Pause frames observed)

Priority : 7 0 0

 

user@switch> show snmp mib get 1.3.6.1.2.1.10.7.10.1.3.669

dot3InPauseFrames.669 = 506066

Solution

On QFX5120 (and on other Junos QFX5K) Priority Flow Control (PFC) stats are not supported via SNMP. It is only available in CLI ( show interfaces extensive <>). 

 

All Junos EVO based QFX5K platforms like QFX5220, QFX5130, QFX5230 & QFX5240 supports PFC stats via SNMP and telemetry. 

 

MIB Reference:

https://apps.juniper.net/mib-explorer/navigate?software=Junos%20OS%20Evolved&release=25.2R1&name=jnxCosPfcPriorityTable&oid=1.3.6.1.4.1.2636.3.15.11




 

Modification History

2025-09-03 : Article Created