2013年6月27日星期四

Sampled netflow from Nexus 7000 questions


Question:

We have Nexus 7000s configured WS-C3560X-24T-S for sampled netflow. We have tools that should reconstruct the sampled flow records for management displays. Most tools require the flow record, option and template to be sent in order to reconstruct the sampled flow record. We have captured some of this traffic and noticed that the template contains "SamplerMode": Unknown (1) [See Nexus 1-1.png]. Is this usual or have we not include commands required for proper operation?

fearure netflow
flow timeout active 60
flow timeout inactive 15 (default)
flow session
flow timeout agreesive threshold 80

flow exporter flow_exporter
destination x.x.x.x use-vrf management
transport udp 9996
version 9
  template data timeout 30
  option exporter-stats timeout 30
  option sampler-table timeout 60

flow record flow_record
match ipv4 source address
! {many statments}

sampler netflow_sampler-2
  mode 1 out-of 100

flow monitor flow_monitor
    record flow_record
    exporter flow_exporter

interface VLAN 150
ip flow monitor flow_monitor output sampler netflow_sampler-2

Answer:


You are correct regarding "Most tools require the flow record, option and template" and they also require the definitions of all elements used in the export.

We maintain constant communication with Cisco for their latest element IDs and definitions (I.e. description, type, length, etc.).  It looks like your collector may need the definitions.  Once updated, the front end will then need to be updated to make use of the new element(s) if you want to make use of it.

If you send a packet capture of the flows to Plixer the will give you a more complete diagnosis. Make WS-C3560X-48T-L Price sure you include the templates.  

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