How to troubleshoot Dot1Q sub-interface input drops

[ernesttelecom1]

Hello there, i've been trying to troubleshoot sub interface input drops but I can't figure out how to look deeper into the counters for sub interface instead of physical ones. I'm not clear what counters show up in the show interface Total Input Drops. Appreciate your help.

RP/0/RSP0/CPU0:ASR001#show interfaces tenGigE 0/4/0/2.868 Mon May 15 11:22:48.056 EDT TenGigE0/4/0/2.868 is up, line protocol is up Interface state transitions: 39 Hardware is VLAN sub-interface(s), address is 78ba.f90f.87e2 Description: Internet address is 10.10.10.1/30 MTU 1518 bytes, BW 10000000 Kbit (Max: 10000000 Kbit) reliability 255/255, txload 3/255, rxload 43/255 Encapsulation 802.1Q Virtual LAN, VLAN Id 868, loopback not set, ARP type ARPA, ARP timeout 04:00:00 Last input 00:00:00, output 00:00:00 Last clearing of "show interface" counters 3d18h 30 second input rate 1723289000 bits/sec, 202175 packets/sec 30 second output rate 125656000 bits/sec, 33467 packets/sec 66035997122 packets input, 75885173087508 bytes, 47007357 total input drops 162342 drops for unrecognized upper-level protocol Received 5 broadcast packets, 164117 multicast packets 10329221447 packets output, 4993624967077 bytes, 0 total output drops Output 0 broadcast packets, 0 multicast packets RP/0/RSP0/CPU0:ASR001#

RP/0/RSP0/CPU0:ASR001#show interfaces tenGigE 0/4/0/2 Mon May 15 11:18:46.559 EDT TenGigE0/4/0/2 is up, line protocol is up Interface state transitions: 39 Dampening enabled: penalty 0, not suppressed half-life: 1 reuse: 250 suppress: 950 max-suppress-time: 1 restart-penalty: 0 Hardware is TenGigE, address is 78ba.f90f.553e (bia 78ba.f90f.87e2) Layer 1 Transport Mode is LAN Description:  Internet address is Unknown MTU 1514 bytes, BW 10000000 Kbit (Max: 10000000 Kbit) reliability 255/255, txload 3/255, rxload 40/255 Encapsulation ARPA, Full-duplex, 10000Mb/s, link type is force-up output flow control is off, input flow control is off loopback not set, Last input 00:00:00, output 00:00:00 Last clearing of "show interface" counters 2d23h 30 second input rate 1569587000 bits/sec, 190694 packets/sec 30 second output rate 120750000 bits/sec, 30554 packets/sec 52603743184 packets input, 60674409000729 bytes, 8557 total input drops 8557 drops for unrecognized upper-level protocol Received 4 broadcast packets, 268141 multicast packets 0 runts, 0 giants, 0 throttles, 0 parity 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 8133483702 packets output, 3845804316656 bytes, 0 total output drops Output 0 broadcast packets, 2850 multicast packets 0 output errors, 0 underruns, 0 applique, 0 resets 0 output buffer failures, 0 output buffers swapped out 0 carrier transitions RP/0/RSP0/CPU0:ASR001#

RP/0/RSP0/CPU0:ASR001#show controllers tenGigE 0/4/0/2 stats
Fri May 12 09:30:33.240 EDT
Statistics for interface TenGigE0/4/0/2 (cached values):

Ingress:
Input total bytes = 1036800258134601
Input good bytes = 1036800258134601

Input total packets = 877557094826
Input 802.1Q frames = 0
Input pause frames = 0
Input pkts 64 bytes = 662058
Input pkts 65-127 bytes = 131103195621
Input pkts 128-255 bytes = 31965759539
Input pkts 256-511 bytes = 16742145382
Input pkts 512-1023 bytes = 34264891911
Input pkts 1024-1518 bytes = 197143224682
Input pkts 1519-Max bytes = 466337215633

Input good pkts = 877556432730
Input unicast pkts = 877536359707
Input multicast pkts = 20734754
Input broadcast pkts = 365

Input drop overrun = 0
Input drop abort = 0
Input drop invalid VLAN = 0
Input drop invalid DMAC = 0
Input drop invalid encap = 0
Input drop other = 662092 <<-- Does this counter appear in the show interface input drops?

Input error giant = 4
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 = 466337215633
Input MIB jabber = 0
Input MIB CRC = 0

RP/0/RSP0/CPU0:ASR001#show drops np np1 location 0/4/CPU0
Fri May 12 09:39:40.401 EDT

Node: 0/4/CPU0:
----------------------------------------------------------------

NP 1 Drops:                                                                  <<--Does this counters show up under the show interface/subinterface Total Input Drops?
----------------------------------------------------------------
RSV_DROP_IPV4_TXADJ_NO_MATCH                        12
RSV_DROP_IPV4_DROP_NULL_RTE 14
RSV_EGR_LAG_NOT_LOCAL_DROP_CNT           5625286
IPV4_TTL_ERROR_EXCD                                       4927
MDF_PUNT_POLICE_DROP                                     4927
----------------------------------------------------------------
RP/0/RSP0/CPU0:ASR001#

Thanks in advance

[Aleksandar Vidakovic · Accepted solution]

Physical controller drop counters should contribute to the "total input drops" of the main interface, but not the sub-interface.

At NP microcode level, all drop counters where the input interface is know in the current microcode context are contributing to the "total input drops" at sub-interface level (also at interface level if that's where packets are logically received). You can use the "monitor np interface" feature to zoom into this. This command is described in https://supportforums.cisco.com/document/12927596/asr9000xr-troubleshooting-packet-drops-drops-np-microcode.

It is possible that some control plane drops are also contributing to "total input drops". One example are ES-IS PDU drops by IS-IS. This is unfortunately not an easy one to answer in today's XR releases. To zoom into these today you would have to run "debug statsd collector".

An enhancement request is in the pipeline to improve further the input drops transparency, but it's not getting much priority. Please feel free to ask someone from your account team at Cisco to reach out to me if you would like to get more priority to this improvement.

hope this helps,

/Aleksandar