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Re: Alternative to NetFlow for Measuring Traffic flows

  • From: William B. Norton
  • Date: Tue Dec 17 01:58:59 2002

Quantifiable Proof and "Peering Profiles"...see below.

At 08:53 PM 12/16/2002 -0800, Joe Wood wrote:

On Mon, 16 Dec 2002, Joe Abley wrote:

> I think the idea was to say "well, from the mrtg graph, the difference
> between this circuit with all my _9327_ traffic and this circuit
> without any _9327_ traffic, at what I might reasonably estimate their
> peak time to be, looks to be about 2 megs or so".
>
> It's a pretty crude measure, but it does have the advantage of
> requiring no more than mrtg and a route-map to set up.
Right, it is crude, but in an economy where business decisions require "Quantifiable *Proof*", this is quantifiable and easy to do. Some Peering Coordinators are putting together business plans now for peering at the IX that includes the #'s of Mbps of peering traffic, and e-mail confirmation from the peers at the IX that they will indeed peer with them at the IX. Smart customers; if they exceed the breakeven point then peering makes sense. A lot more work up front than it used to be.


It is also useful as a supplement to netflow statistics, as sort of a
verification to your flow data. Sometimes due to design, operating
conditions, etc netflow data is not always the most reliable and/or
meaningful.

As an example:

You run two main types of border router platforms. On one platform you
must sample netflow @ 1% due to performance limitations. On the other
platform there is no sampling functionality built into the software.
This creates an immediate skew of data, unless software is created to
sample the flows coming off the second platform.

Now take into account that your traffic is mainly outbound from your
network, which means that you need to ignore vendor best practice
and enable flow caching on your core (internal) facing interfaces to
measure the traffic flowing out of your network.

So, in order for you to get any kind of traffic statistics for a peer,
you've got to spend many hours distilling data manually, doing AS
aggregations, and create a possibly unstable networking environment.

No big deal, right?

It may be crude, but sometimes it can be the most reliable _available_
method to tell how much traffic is going to the ISP and ISP customers.
Joe is absolutely right here, and this still represents a common scenario and problem for the peering community.

Another approach I have been thinking about is to generate "Peering Profiles" for the community...here is how it works. Let's say I work with a few Internet Gaming companies and find that the netflow stats show a certain pattern, or profile of traffic destinations. Maybe I find that
2% to Cox
3% to Shaw
2% to Comcast
5% to Roadrunner
2% to Adelphia
and the next top 20 ASes represent the next 10% of traffic.

Anonymized, this "Peering Profile" for Internet Gaming companies can probably be applied to other Internet Gaming companies and can provide a rough idea of good targets for peering and how much traffic can be expected at a peering point, as a percentage of their total traffic. Empirically, these top traffic destinations and volumes have been large enough, 10's of Mbps each, generally more than enough to justify peering a an IX where the breakeven point is 10-30Mbps. The design of the tool/template is pretty obvious from there.

Side Note: See all the trouble we go through because traffic flow measurement is still non-trivial? If the netflow data is available at ingress/egress points, I was pointed to http://ehnt.sourceforge.net/ as a good freeware tool for evaluating and translating the netflow raw data.

Bill





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