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Cisco Bug: CSCvv93835 - RPF drops seen (incrementing) even when RPF is not enabled

Last Modified

Oct 01, 2020

Products (1)

  • Cisco Carrier Routing System

Known Affected Releases

5.3.3.CE

Description (partial)

Symptom:
Seeing RPF drop counters (increasing)  in the ipv6 CEF table even when RPF is not enabled.

RP/0/RP0/CPU0:dlstx405igs#sh cef ipv6 drops location 0/2/CPU0
CEF Drop Statistics
Node: 0/2/CPU0
  Unresolved drops     packets :               0
  Unsupported drops    packets :               0
  Null0 drops          packets :          989389
  No route drops       packets :           37956
  No Adjacency drops   packets :               0
  Checksum error drops packets :               0
  RPF drops            packets :     31868266305
  RPF suppressed drops packets :               0
  RP destined drops    packets :               0
  Discard drops        packets :               0
  GRE lookup drops     packets :               0
  GRE processing drops packets :               0
  LISP punt drops      packets :               0
  LISP encap err drops packets :               0
  LISP decap err drops packets :               0
RP/0/RP0/CPU0:dlstx405igs#sh cef ipv6 drops location 0/2/CPU0
CEF Drop Statistics
Node: 0/2/CPU0
  Unresolved drops     packets :               0
  Unsupported drops    packets :               0
  Null0 drops          packets :          989389
  No route drops       packets :           37956
  No Adjacency drops   packets :               0
  Checksum error drops packets :               0
  RPF drops            packets :     31868291904
  RPF suppressed drops packets :               0
  RP destined drops    packets :               0
  Discard drops        packets :               0
  GRE lookup drops     packets :               0
  GRE processing drops packets :               0
  LISP punt drops      packets :               0
  LISP encap err drops packets :               0
  LISP decap err drops packets :               0
RP/0/RP0/CPU0:dlstx405igs#

Conditions:
Customer at one point had RPF enabled and was hitting a knwong ddts  and then disabled it . But even after disabling, they were seeing RPF drops on multiple nodes. bundle int shows RPF enabled in the UIDB output.

RP/0/RP0/CPU0:dlstx405igs#show uidb data bundle-ether 7 location 0/6/CPU0 | in IPV6
  IPV6 ENABLE: 1
  IPV6 MULTICAST: 0
  USE TABLE ID IPV6: 0
  IPV6 ICMP PUNT: 1
  IPV6 NETFLOW SAMPLING ENABLE: 1
  IPV6 BGP POLICY ACCOUNTING: 0
  IPV6 BGP POLICY ACCOUNTING SRC: 0
  IPV6 BGP POLICY ACCOUNTING DST: 0
  IPV6 BGP POLICY ACCOUNTING STATS POINTER: 0x0
  IPV6 QOS POLICY PROPAGATION VIA BGP SRC: Disabled (0)
  IPV6 QOS POLICY PROPAGATION VIA BGP DST: Enabled (1)
  IPV6 ACL COUNT: 1
  IPV6 ACL ENABLE: 1
  IPV6 ACL COMMON ENABLE: 0
  IPV6 ACL ID: 2
  IPV6 ACL STATS INDEX: 0
  IPV6 MULTICAST BOUNDARY ACL: 0
  IPV6 RPF CHECK: 1
  IPV6 RPF ALLOW SELF PING: 1
  IPV6 RPF ALLOW DEFAULT: 0
  IPV6 RPF STRICT: 0
  IPV6 SRC LOOKUP NEEDED: 1
  IPV6 EFFECTIVE UIDB INDEX: 0
RP/0/RP0/CPU0:dlstx405igs#
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