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Cisco Bug: CSCvt13462 - NX-OS: BGP memory leak within 'BGP BF slab' when more than 30 neighbors configured

Last Modified

Sep 03, 2020

Products (67)

  • Cisco Nexus 9000 Series Switches
  • Cisco Nexus 3548-X Switch
  • Cisco Nexus 92348GC-X Switch
  • Cisco Nexus 3548 Switch
  • Cisco Nexus 9516 Switch
  • Cisco Nexus 3636C-R Switch
  • Cisco Nexus 93600CD-GX Switch
  • Cisco Nexus 3132Q-V Switch
  • Cisco Nexus 9396TX Switch
  • Cisco Nexus 93108TC-FX Switch
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Known Affected Releases

9.3(1) 9.3(3)

Description (partial)

Symptom:
A Cisco Nexus switch might see BGP brought down across multiple neighbors because of memory exhaustion. 

The progression of this would look like the following:

BGP-5-MEMALERT:  bgp- [pid]  BGP memory status changed from OK to Severe Alert
BGP-5-MEMALERT:  bgp- [pid]  BGP memory status changed from Severe Alert to Critical 
BGP-5-MEMALERT:  bgp- [pid]  BGP memory status changed from OK to Critical Alert
BGP-2-PEERSHALTED:  bgp- [pid]  BGP <neighbor> shutdown due to no memory condition (Critical Alert)

The symptoms of this would show growth / large value held (when BGP flapped) in the following library:

`show bgp internal mem-stats all detail`

Private Mem stats for UUID : Slab Library(529) Max types: 2
--------------------------------------------------------------------------------
TYPE NAME                                           ALLOCS                 BYTES
                                               CURR    MAX       CURR        MAX
   1 LIBSLAB_MEM_create_slab                  35216  35575 2532632952 2566313240 <--- 2.5GB
--------------------------------------------------------------------------------
Total bytes: 2532632952 (2473274k)
--------------------------------------------------------------------------------
 
And the following:

SLAB: BGP BF slab (24 x 3000)
Slab alloc count               : 105352941  
Slab max allocs                : 105352941
Slab total allocs              : 105352941
Slab total frees               : 0  <----- No frees are happening
Slab total block allocs        : 35118
Slab block alloc failures      : 0
Slab total block frees         : 0
Slab max blocks                : 35118

Conditions:
At some point the router was configured with more than 30 bgp neighbors
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