Re: CAR and netflow

From: Jeffrey Papen (
Date: Tue Jul 17 2001 - 13:45:32 PDT

  • Next message: Stefan Peter: "Problems with incoming traffic"

    From this URL:

    I read this.

    Non-NetFlow enabled switching handles incoming packets independently, with separate serial tasks for switching, security, services and traffic measurements applied to each packet. With NetFlow-enabled switching, security (ACL) processing is applied only to the first packet of a flow. Information from the first packet is used to build an entry in the NetFlow cache. Subsequent packets in the flow are handled via a single streamlined task that handles switching, services and data collection concurrently.


    NetFlow provides the measurement base for Cisco's Internet and Enterprise QoS initiatives. NetFlow records the Type of Service (ToS) field in the IP header as well as application ports, traffic volumes and timestamps. Thus, service providers can charge premium charges for premium packets as well as charging based on usage, time and application. NetFlow does not accelerate QoS services such as traffic classification or Committed Access Rate (CAR). Note that NetFlow itself is not a QoS feature; it simply captures the Quality of Service level of each flow.

    Hope this helps.

    - Jeffrey

    Dana Watanabe wrote:

    > Is it correct that things like ACLs and CAR get implemented after Netflow
    > stats have been made on the packets?
    > If so, is there any way to deal with that?
    > In particular we have have reports of how much each department is using, but
    > we also have CAR set up limiting particular types of traffic leaving our
    > campus. We're trying to work toward some sort of useage based billing
    > system, but we can't use the data if traffic is being counted but isn't
    > actually going through.
    > --
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