Re: IP OVER ATM

[Philip Smith <pfs at cisco.com>]

Hi,

Some more food for thought for you...

If you have an existing ATM network:

   ...then IP over ATM will work just fine, as IP does on any other 
transport media. You just need to be aware of the fact that the ATM cell 
size is smaller than the smallest IP packet, so a single IP packet will 
require at least two ATM cells to accommodate it. On IP over ATM networks 
with typical Internet traffic you will hear people talking about a "cell 
tax" of around 30%. In otherwords, 30% of your available bandwidth is lost 
because of the ATM overhead. There have been several experiments to 
demonstrate the cell tax, one that I was involved in demonstrated an STM-1 
"circuit" with theoretical capacity of 155Mbps carrying 149Mbps of traffic 
with IP/Sonet and 110Mbps of traffic with IP/ATM before packet loss. Losing 
39Mbps to cell tax in this case = lost revenue + extra outlay at no gain.

If you do not have an existing ATM network:

   ...and you are contemplating installing an ATM network just to carry IP, 
then maybe you should consider other technologies as ATM is very much a 
technology on the way out (like FDDI, X.25, etc). Why can't you run IP over 
the native infrastructure? If you want to use cell/frame type technologies, 
maybe Frame Relay makes more sense (as Bill Woodcock offered)? No one with 
an eye to the future is installing ATM to transport IP these days.

philip
--

At 17:44 02/06/2003 +0100, Modou Salifu Jatta wrote:
>Hi Guys,
>My company is planning to deploy IP OVER ATM but am not very comfortable
>about it.Well if any one has experience with ATM I would be grateful for any
>advice with regards to scalability and future prospects of the technology.
>Regards!
>
>msjatta
>
>
>-----
>This is the afnog mailing list, managed by Majordomo 1.94.5
>
>To send a message to this list, e-mail afnog at afnog.org
>To send a request to majordomo, e-mail majordomo at afnog.org and put
>your request in the body of the message (i.e use "help" for help)
>
>This list is maintained by owner-afnog at afnog.org

-----
This is the afnog mailing list, managed by Majordomo 1.94.5

To send a message to this list, e-mail afnog at afnog.org
To send a request to majordomo, e-mail majordomo at afnog.org and put
your request in the body of the message (i.e use "help" for help)

This list is maintained by owner-afnog at afnog.org