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Re: Do ATM-based Exchange Points make sense anymore?

  • From: Nenad Trifunovic
  • Date: Fri Aug 09 17:21:32 2002

It appears that for analysis purposes one has to separate access
from switching. How much payload one brings to the exchange depends
on port speed and protocol overhead. In that light, Frame Relay
can bring similar amount of payload as Ethernet (comparable overhead)
and preserve good properties of ATM (traffic flow separation). 


both juniper 160 and cisco gsr can handle oc-48 frame relay, and
they don't seem to be frame relay switches

>Date: Fri, 09 Aug 2002 13:42 -0700 (PDT)
>From: "William B. Norton" <>
>To: Nenad Trifunovic <>
>Subject: Re: Do ATM-based Exchange Points make sense anymore?
>>Can you, please, explain why you didn't consider Frame Relay
>>based exchange in your analysis?
>I don't have much insight into Frame Relay-based Internet Exchange Points ;-)
>The majority of IXes around the world are ethernet-based, with some legacy 
>FDDI and a few ATM IXes. It is in these areas that I have done the most 
>data collection. The same analysis could be applied to peering across WANs 
>and MANs as compared with buying transit though. It might be interesting 
>provided I can get some market prices for transport and ports.
>Why look at ATM?  Right now almost everyone I am speaking with is seeing 
>massive drops in transit and transport prices, even below the points I 
>quoted, but with no comparable price drop in ATM ports or transport into an 
>ATM cloud. These forces lead to a point where a connection to an ATM IX 
>makes no sense (from a strictly financial standpoint). I have another 10 
>folks to walk through the paper to make sure I'm not missing anything in 
>the analysis, and I'll post to the list when the paper is available. If you 
>are interested I'd love to walk you through it to get your take.
>One point a couple other folks brought up during the review (paraphrasing) 
>"You can't talk about a 20% ATM cell tax on the ATM-based IX side without 
>counting the HDLC Framing Overhead (4%) for the OC-x circuit into an 
>ethernet-based IX." Since the "Effective Peering Bandwidth" is the max 
>peering that can be done across the peering infrastructure, this is a good 
>point and has now been factored into the model and analysis.

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