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Cisco Bug: CSCvv24436 - Fabricpath - Additional HSRP Anycast group config causes MCM MTS Buffer Buildup

Last Modified

Oct 19, 2020

Products (1)

  • CiscoPro Workgroup EtherSwitch Software

Known Affected Releases

7.3(4)D1(1) 8.2(4) 8.2(6) 8.4(2)

Description (partial)

Symptom:
MTS buffer increases every second 

SD010104-BGL14.1.K.18-N7K1-itchb(config-if-range)# sh sys int mts buff sum
node    sapno   recv_q  pers_q  npers_q log_q
sup     4968    0       0       1       0
sup     284     0       2       0       0
sup     1       1       0       0       0
sup-1   448     3       6       0       0
sup-1   452     0       1       0       0
sup-1   196     0       3       0       0
sup-1   453     56202   26744   0       0
sup-1   284     0       2       0       0
SD010104-BGL14.1.K.18-N7K1-itchb(config-if-range)# sh sys int mts buff sum
node    sapno   recv_q  pers_q  npers_q log_q
sup     4968    0       0       1       0
sup     284     0       2       0       0
sup-1   448     0       5       0       0
sup-1   452     0       0       1       1
sup-1   196     0       4       0       0
sup-1   340     2       1       0       0
sup-1   453     57295   26925   0       0               <-----Increase
sup-1   174     1       0       0       0
sup-1   284     0       2       0       0
sup-1   279     0       1       0       0
SD010104-BGL14.1.K.18-N7K1-itchb(config-if-range)# sh sys int mts buff sum
node    sapno   recv_q  pers_q  npers_q log_q
sup     4968    0       0       1       0
sup     284     0       2       0       0
sup-1   448     2       4       0       0
sup-1   452     0       1       0       0
sup-1   196     0       9       0       0
sup-1   340     1       1       0       0
sup-1   453     57993   27039   0       0                <-----Increase
sup-1   284     0       2       0       0
SD010104-BGL14.1.K.18-N7K1-itchb(config-if-range)# sh sys int mts buff sum
node    sapno   recv_q  pers_q  npers_q log_q
sup     4968    0       0       1       0
sup     284     0       2       0       0
sup-1   448     7       2       0       0
sup-1   196     0       7       0       0
sup-1   453     58541   27131   0       0               <-----Increase
sup-1   284     0       2       0       0
SD010104-BGL14.1.K.18-N7K1-itchb(config-if-range)# sh sys int mts buff sum
node    sapno   recv_q  pers_q  npers_q log_q
sup     4968    0       0       1       0
sup     284     0       2       0       0
sup-1   1195    0       1       0       0
sup-1   448     0       8       0       0
sup-1   196     0       1       0       0
sup-1   340     0       1       0       0
sup-1   453     59186   27242   0       0               <-----Increase
sup-1   284     0       2       0       0


An SVI that is configured with the additional hsrp group that is part of an Anycast group will flap between Initial and Active state  

SD010104-BGL14.1.K.18-N7K1-itchb(config-if-range)# sh hsrp anycast br
----------------------------------------------------------------
 Bundle/addr    Prio Switch.ID Track.ID   State     Vlans 
 * = Up
----------------------------------------------------------------
 100/IPv4    *  120   4000       N/A       Active     3561,3571,3581,3591,3611,3811,3821,3831,3901 
 101/IPv4    *  50    4001       N/A       Active     3562,3572,3582,3612,3812,3822,3832 
 102/IPv4    *  120   4002       N/A       Active     3563,3573,3583,3593,3613,3813,3823,3833 
 103/IPv4    *  120   4003       N/A       Active     3564,3574,3584,3594,3614,3814,3824 
 104/IPv4    *  120   4004       N/A       Active     3565,3575,3585,3595,3615,3815,3825 
 105/IPv4      120   4005       N/A       Initial    3566,3576,3596,3616,3816,3826,3836 
 106/IPv4    *  120   4006       N/A       Active     3567,3577,3587,3597,3817,3827,3837 
 107/IPv4    *  120   4007       N/A       Active     3568,3578,3588,3598,3628,3818,3828,3838 
 108/IPv4    *  120   4008       N/A       Active     3569,3579,3589,3819,3829,3839 
 109/IPv4    *  120   4009       N/A       Active     3570,3580,3590,3820,3830,3840  
 110/IPv4      120   4010       N/A       Active     3618-3627,3834                         <------------

SD010104-BGL14.1.K.18-N7K1-itchb(config-if-range)# sh hsrp anycast br
----------------------------------------------------------------
 Bundle/addr    Prio Switch.ID Track.ID   State     Vlans 
 * = Up
----------------------------------------------------------------
 100/IPv4    *  120   4000       N/A       Active     3561,3571,3581,3591,3611,3811,3821,3831,3901 
 101/IPv4    *  50    4001       N/A       Active     3562,3572,3582,3612,3812,3822,3832 
 102/IPv4    *  120   4002       N/A       Active     3563,3573,3583,3593,3613,3813,3823,3833 
 103/IPv4    *  120   4003       N/A       Active     3564,3574,3584,3594,3614,3814,3824 
 104/IPv4    *  120   4004       N/A       Active     3565,3575,3585,3595,3615,3815,3825 
 105/IPv4      120   4005       N/A       Initial    3566,3576,3596,3616,3816,3826,3836 
 106/IPv4    *  120   4006       N/A       Active     3567,3577,3587,3597,3817,3827,3837 
 107/IPv4    *  120   4007       N/A       Active     3568,3578,3588,3598,3628,3818,3828,3838 
 108/IPv4    *  120   4008       N/A       Active     3569,3579,3589,3819,3829,3839 
 109/IPv4    *  120   4009       N/A       Active     3570,3580,3590,3820,3830,3840 
 110/IPv4      120   4010       N/A       Initial    3618-3627,3834                          <-----------------

Conditions:
Device is running Fabricpath on 7.3(4)D1(1), 8.2.4, 8.2.6, or 8.4.2 code on N7K

An additional group is added to a vlan SVI that has been configured to be a part of an Anycast HSRP group:
 
hsrp anycast 105 ipv4
  switch-id 4005
   force gateway-down
  vlan 3566,3576,3596,3616,3816,3826,3836
  priority 120
  no shutdown

hsrp anycast 110 ipv4
  switch-id 4010
   force gateway-down
  vlan 3618-3627,3834
  priority 120
  no shutdown

interface Vlan3624 <---Part of anycast 110
  hsrp version 2
  hsrp 88 
    ip 130.199.163.254
  hsrp 91 <------ Issue Configuration

interface Vlan3826  <---Part of anycast 105
  hsrp version 2    
  hsrp 46 
    ip 130.203.91.254
  hsrp 49 <------ Issue Configuration
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