[c-nsp] ASR9k - input drops

[Pshem Kowalczyk]

Hi,

We're trying to determine a cause of 'total input drops' on one of
TenG interfaces on ASR9k. The interface is a CE facing one.
(statistics have not been cleared, but the issue is ongoing):


TenGigE0/2/0/2 is up, line protocol is up
  Interface state transitions: 3
  Hardware is TenGigE, address is 0026.51c7.7c72 (bia 0026.51c7.7c72)
  Layer 1 Transport Mode is LAN
  Description: RIC ETH55 IDA100547449
  Internet address is Unknown
  MTU 9100 bytes, BW 10000000 Kbit
     reliability 255/255, txload 0/255, rxload 0/255
  Encapsulation ARPA,
  Full-duplex, 10000Mb/s, LR, link type is force-up
  output flow control is off, input flow control is off
  loopback not set,
  Maintenance is enabled,
  ARP type ARPA, ARP timeout 04:00:00
  Last input 00:00:00, output 00:00:00
  Last clearing of "show interface" counters never
  5 minute input rate 29804000 bits/sec, 16890 packets/sec
  5 minute output rate 27375000 bits/sec, 14317 packets/sec
     72867439423 packets input, 28161167294502 bytes, 2009080145 total
input drops <-------------
     0 drops for unrecognized upper-level protocol
     Received 56581832 broadcast packets, 259175 multicast packets
              0 runts, 0 giants, 0 throttles, 0 parity
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     68009941001 packets output, 28145762923844 bytes, 0 total output drops
     Output 149319242 broadcast packets, 12 multicast packets
     0 output errors, 0 underruns, 0 applique, 0 resets
     0 output buffer failures, 0 output buffers swapped out
     3 carrier transitions

There is nothing in QoS stats:

RP/0/RSP0/CPU0:SPNZTRC01#sh policy-map interface te0/2/0/2 | inc drop
Wed Feb 16 14:36:04.291 NST
    Policed and dropped :                   0/0
    Policed and dropped :                   0/0
    Policed and dropped :                   0/0
    Policed and dropped :                   0/0
    Policed and dropped :                   0/0
    Taildropped(packets/bytes)           : 0/0
    RED random drops(packets/bytes)      : 0/0
    Policed and dropped :                   0/0
    Taildropped(packets/bytes)           : 0/0
    RED random drops(packets/bytes)      : 0/0
    Policed and dropped :                   0/0
    Policed and dropped :                   0/0
    Taildropped(packets/bytes)           : 0/0
    RED random drops(packets/bytes)      : 0/0

Nothing in the controller stats either:


Statistics for interface TenGigE0/2/0/2 (cached values):

Ingress:
    Input total bytes           = 28161868016008
    Input good bytes            = 28161868016008

    Input total packets         = 72870660366
    Input 802.1Q frames         = 0
    Input pause frames          = 0
    Input pkts 64 bytes         = 0
    Input pkts 65-127 bytes     = 15972559313
    Input pkts 128-255 bytes    = 1426886684
    Input pkts 256-511 bytes    = 54131742869
    Input pkts 512-1023 bytes   = 109006345
    Input pkts 1024-1518 bytes  = 0
    Input pkts 1519-Max bytes   = 1230465155

    Input good pkts             = 72870660366
    Input unicast pkts          = 72813817202
    Input multicast pkts        = 259175
    Input broadcast pkts        = 56583989

    Input drop overrun          = 0
    Input drop abort            = 0
    Input drop unknown 802.1Q   = 0
    Input drop other            = 0

    Input error giant           = 0
    Input error runt            = 0
    Input error jabbers         = 0
    Input error fragments       = 0
    Input error CRC             = 0
    Input error collisions      = 0
    Input error symbol          = 0

    Input error other           = 0

    Input MIB giant             = 1230465155
    Input MIB jabber            = 0
    Input MIB CRC               = 0


Any idea what that value (total input drops) actually refers to? We do
not seem to have any reports from the customers about degraded
performance, but nonetheless it's worrying.

kind regards
Pshem