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Strange interface counters when QOS applyed on serial interface

Hi Guys,

I have two 2951 routers connected by serial lines, same IOS.

With NO QOS applied, both serial has similiar counters on pkgs and chars/bytes:
R1 output = R2 input AND R2 output = R2 input.

=== R1 with NO QOS =================================================

sh int s0/0/0
  Last clearing of "show interface" counters 00:02:00
  Queueing strategy: fifo
  30 second input rate 247000 bits/sec, 253 packets/sec
  30 second output rate 820000 bits/sec, 233 packets/sec
     32761 packets input, 4493558 bytes, 0 no buffer
     31947 packets output, 16002224 bytes, 0 underruns

sh int s0/0/0 acc
                Protocol    Pkts In   Chars In   Pkts Out  Chars Out
                      IP      32747    4492550      31933   16002299

=== R2 with NO QOS =================================================

sh int s0/0/0
  Last clearing of "show interface" counters 00:02:00
  Queueing strategy: fifo
  30 second input rate 836000 bits/sec, 232 packets/sec
  30 second output rate 246000 bits/sec, 253 packets/sec
     31951 packets input, 16002444 bytes, 0 no buffer
     32788 packets output, 4495147 bytes, 0 underruns

sh int s0/0/0 acc
                Protocol    Pkts In   Chars In   Pkts Out  Chars Out
                      IP      31955   16011564      32811    4498482

With QOS applied, both serial has similiar counters on pkgs and very different counters on chars/bytes.
R1 output = R2 input and R2 output = R1 input (only pkgs, not in char/bytes)

=== R1 with QOS ====================================================

sh int s0/0/0
  Last clearing of "show interface" counters 00:02:01
  Queueing strategy: Class-based queueing
  30 second input rate 404000 bits/sec, 365 packets/sec
  30 second output rate 116000 bits/sec, 363 packets/sec
     44298 packets input, 6286247 bytes, 0 no buffer
     42344 packets output, 1724160 bytes, 0 underruns

sh int s0/0/0 acc
                Protocol    Pkts In   Chars In   Pkts Out  Chars Out
                      IP      44285    6285502       6724    1717527

=== R2 with QOS ====================================================

sh int s0/0/0
  Last clearing of "show interface" counters 00:02:01
  Queueing strategy: Class-based queueing
  30 second input rate 1622000 bits/sec, 359 packets/sec
  30 second output rate 416000 bits/sec, 366 packets/sec
     42344 packets input, 24839624 bytes, 0 no buffer
     44311 packets output, 6286875 bytes, 0 underruns

sh int s0/0/0 acc
                Protocol    Pkts In   Chars In   Pkts Out  Chars Out
                      IP      42340   24839972      35470    4650871

The traffic is flowing fine. The problem apperas to be only on interfaces counters on cli/snmp and because this my traffic graphic appears very strange.

Does anyone know something about it or see this behavior? The olders routers with IOS 12 don't have this problem.

This behavior occurs only with IOS 15.2 and 15.3, the 2 versions I had a chance to test.

I'm missing something or this is a possible bug? I dont see anything on bug search tool related to this ios/platform.

Thanks

Luiz

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