Guest

Preview Tool

Cisco Bug: CSCuq52496 - FNF: platform runs out of big buffers

Last Modified

May 26, 2020

Products (2)

  • Cisco IOS
  • Cisco Catalyst 6500 Series Supervisor Engine 2T

Known Affected Releases

15.0(1)SY

Description (partial)

Symptom:
On a device running Flexible NetFlow, a memory depletion condition may be observed on one or more DFC-equipped line cards. This will be seen as high Processor pool utilization under "NF SE export thr" and high utilization in Big buffers in the I/O pool. It may also result in MALLOCFAIL messages being reported by the affected DFC.

Attaching to the line card will show similar to the following:

Switch-dfc2#sh processes memory sorted
Processor Pool Total:  995716064 Used:  974838252 Free:   20877812

 PID TTY  Allocated      Freed    Holding    Getbufs    Retbufs Process
 272   0 1921598164 1370667188  550891476  334977084          0 NF SE export thr  <------
 245   0 1535576692 1418236700  117343836   71331336          0 fw_lcp process  
   0   0  122611856      24532  116498704          0          0 *Init*          
 299   0  574069872  526121488   47971160   29369736          0 QoS SP Process  
  77   0   43999292       4240   39966888    3384000          0 PF_Init Process 
 254   0 1177436576 1147880168   29572380   17740620          0 Lif stats hw rea
<omitted>

Switch-dfc2# show buffers
<omitted>
Big buffers, 1536 bytes (total 278831, permanent 1000, peak 278831 @ 00:02:54):   <-------
     74 in free list (64 min, 1000 max allowed)
     109005312 hits, 1646454 misses, 46 trims, 277877 created
     946889 failures (6072237 no memory)
<omitted>

Conditions:
Flexible NetFlow must be enabled. This may be observed in situations where a large amount of exported flows must be sent from the line card to the RP. It's more likely to see this on a lower-memory line card (e.g. a non-XL DFC) due to less available system memory.

The depletion may be exacerbated when 'show flow monitor <MONITOR_NAME>' subcommands are executed as this triggers additional data export from the line card to the supervisor.
Bug details contain sensitive information and therefore require a Cisco.com account to be viewed.

Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
  • Severity
  • Known Fixed Releases
  • Related Community Discussions
  • Number of Related Support Cases
Bug information is viewable for customers and partners who have a service contract. Registered users can view up to 200 bugs per month without a service contract.