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Cisco Bug: CSCus85835 - Traffic packet size greater than interface mtu--traffic not dropped

Last Modified

Jan 14, 2017

Products (1)

  • Cisco Carrier Routing System

Known Affected Releases

6.0.0.FWDG

Description (partial)

Symptom:
TOPO:
TGN--sunstone---ASR9K---TGN

The TGN facing interface is Gi0/RP0/CPU0/2.211, mtu is 1514. When sending traffic with pkt size as 2000, the traffic can go through and be fragmented on sunstone egress intf.

RP/0/RP0/CPU0:ott02-sim-012-r1#clear counters
Clear "show interface" counters on all interfaces [confirm]
RP/0/RP0/CPU0:Feb  9 15:18:39.106 : statsd_manager_g[1127]: %MGBL-IFSTATS-6-CLEAR_COUNTERS : Clear counters on all interfaces
RP/0/RP0/CPU0:ott02-sim-012-r1#sh int Gi0/RP0/CPU0/2.211 acc
GigabitEthernet0/RP0/CPU0/2.211
  Protocol              Pkts In         Chars In     Pkts Out        Chars Out
  IPV4_UNICAST             3466           242620            0                0
  IPV4_MULTICAST              0                0         3469           242830
  IPV6_UNICAST                1               72            0                0
  MPLS                    86499         84088055        14544         11296095
  CLNS                        5             6191            1             1493


RP/0/RP0/CPU0:ott02-sim-012-r1#                     



RP/0/RP0/CPU0:ott02-sim-012-uut#sh int Gi0/RP0/CPU0/0.102 acc  <---ingress, traffic supposed to drop here.
GigabitEthernet0/RP0/CPU0/0.102
  Protocol              Pkts In         Chars In     Pkts Out        Chars Out
  IPV4_UNICAST             1601          3166778            0                0
  IPV4_MULTICAST              0                0           31             2170
  IPV6_UNICAST                3              200            1               72
  IPV6_ND                     3              254            3              216
  CLNS                       62            91297          130           171299


RP/0/RP0/CPU0:ott02-sim-012-uut#sh int Gi0/RP0/CPU0/2.211 acc  <---egress
GigabitEthernet0/RP0/CPU0/2.211
  Protocol              Pkts In         Chars In     Pkts Out        Chars Out
  IPV4_UNICAST               35             2450         3202         99333630
  IPV4_MULTICAST              0                0           34             2380
  MPLS                        0                0         3202          3269242
  CLNS                       63            92726          134           177071


RP/0/RP0/CPU0:ott02-sim-012-uut#                                              


P/0/RP0/CPU0:ott02-sim-012-uut#sh int Gi0/RP0/CPU0/0
GigabitEthernet0/RP0/CPU0/0 is up, line protocol is up
  Interface state transitions: 3
  Hardware is GigabitEthernet, address is 5246.016a.dd3d (bia 5246.016a.dd3d)
  Internet address is 109.1.0.1/24
  MTU 1514 bytes, BW 1000000 Kbit (Max: 1000000 Kbit)
     reliability 255/255, txload 0/255, rxload 0/255
  Encapsulation ARPA,
  Duplex unknown, 1000Mb/s, link type is force-up
  output flow control is off, input flow control is off
  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 00:03:27
  30 second input rate 0 bits/sec, 0 packets/sec
  30 second output rate 0 bits/sec, 1 packets/sec
     3 packets input, 242 bytes, 0 total input drops
     0 drops for unrecognized upper-level protocol
     Received 0 broadcast packets, 0 multicast packets
              0 runts, 0 giants, 0 throttles, 0 parity
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     140 packets output, 12974 bytes, 0 total output drops
     Output 0 broadcast packets, 114 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/RP0/CPU0:ott02-sim-012-uut#

Conditions:
image:
Refpoint = calvados/release@flex-xr-twig/2
Built By     : kentp
 Built On     : Sun Feb  8 18:23:17 EST 2015
 Build Host   : rtp-ads-552
 Workspace    : /nobackup/kentp/pims/nightly_flex-xr-twig/150208A/workspace
 Source Base  : ios_ena
 Devline      : flex-xr-twig/flex-xr-twig.lu%FLEX-XR-TWIG_NIGHTLY_15_02_08A
 Devline Type : ACME Project (Devline uses a project: flex-xr-twig%133)
 flex-xr-twig   EFR-00000296717   Project
 flex-xr        EFR-00000294743   Project
 ci-531         EFR-00000292004   Lineup
 ci-530         EFR-00000290307   Lineup
 default        EFR-00000289219   Lineup
RP/0/RP0/CPU0:ott02-sim-012-uut#
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