[c-nsp] A9K Netflow export drops

[Christian Kildau]

Hi all,

we're seeing the exact same symptoms on our all our 9001s.
I have opened a TAC case regarding this issue last week.

Will keep you posted!

Best regards,
Chris

On Mon, May 23, 2016 at 6:09 PM, Christian Kildau <me at chrisk.de> wrote:

> Hi all,
>
> we're seeing the exact same symptoms on our all our 9001s.
> I have opened a TAC case regarding this issue last week.
>
> Will keep you posted!
>
> Best regards,
> Chris
>
> On Mon, May 23, 2016 at 6:02 PM, Robert Williams <Robert at custodiandc.com>
> wrote:
>
>> Hi,
>>
>> Doing some more digging, found this from 2014:
>>
>> Netflow specific scale and Limitations are described below:
>>   1. Supports configurable Sampling Rate 1:1 ~ 1: 65535
>>   2. Supports only up to 4 Sampling Rates (or Intervals) per Ethernet LC
>> LC; no such limit for Enhanced Ethernet LC.
>>   3. Up to 4k interfaces/sub-interfaces (4K system limitation) can be
>> configured with flow monitor per system.
>>   4. Supports up to 8 flow exporters per flow monitor
>>   5. Supports up to 1 million flow entries per LC
>>   6. Supports up to 50k flows per second with LC CPU usage up to 50% per
>> Ethernet LC LC
>>   7. Supports upto 100K flows per second with LC CPU usage up to 50% per
>> Enhanced Ethernet LC LC
>>   8. Netflow scale is increased to 200Kpps on Enhanced Ethernet LC based
>> LCs
>>   9. Supports exporting packet rates up to 50k flows per second (100K
>> flows per sec on Enhanced Ethernet LC based LCs) with LC CPU usage up to 50%
>>
>> "Irrespective of the rate at which the NP punts the records to CPU,
>> exporter picks up a maximum of 2000 records at a time from the cache that
>> are eligible for export (timers, network/TCP session events, etc). This is
>> basically to avoid NetIO dropping the packets due to lack of b/w. When the
>> exporter wakes up again, it repeats the same."
>>
>> So, it can collect 100k flows per second, but can only export 2k each
>> time it runs the exporter. The interval for the exporter is unclear however.
>>
>> I've also found out why this is such an issue on our 9001 but not on any
>> of our 900x larger chassis. Looks like on those the hardware punt is being
>> limited to 25kpps per NP because we have some BVIs with Netflow on them.
>> This causes it to distribute the rate limit for punting to ALL the NPs on
>> the LC, even when only two ports are involved in Netflow. Thus, it's
>> "sampled sampling" and so the rate of flow data is significantly lower than
>> the 9001 which is allowing all 100kpps on one NP which has 4 x 10G
>> interfaces punting into it.
>>
>> mmm...
>>
>>
>>
>> Robert Williams
>> Custodian Data Centre
>> Email: Robert at CustodianDC.com
>> http://www.CustodianDC.com
>>
>> -----Original Message-----
>> From: Dale W. Carder [mailto:dwcarder at wisc.edu]
>> Sent: 23 May 2016 16:02
>> To: Robert Williams <Robert at CustodianDC.com>
>> Cc: cisco-nsp at puck.nether.net
>> Subject: Re: [c-nsp] A9K Netflow export drops
>>
>> Thus spake Robert Williams (Robert at CustodianDC.com) on Sat, May 21, 2016
>> at 10:59:50AM +0000:
>> >
>> > I've got an issue on one of our smaller 9001 boxes which is puzzling me.
>> > It suffers from a high rate of netflow export drops (not cache drops)
>> shown here:
>> >
>> > So from what I understand, it is capturing the flows OK but is unable
>> to get the flow data out, for some reason.
>>
>> I can confirm that our 9k's suffer from this also.
>>
>> The last I checked you can export at the rate of 2000 flows/sec.  I have
>> not
>> looked in 2 years or so to see if this limit was configurable yet.
>>
>> > So - what am I missing here? Surely with a cache capability of 1M it
>> should be ok to export flows when were are only around 30,000 of them
>> nicely ticking over?
>>
>> join the club.  :-(
>>
>> Dale
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>
>
>
> --
> http://www.chrisk.de/
>