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RE: iSCSI: Framing Steps
How wonderfull to have among us people that can tell us in one short sentence why ATM failed [to reach the desktop because otherwise it is still gaining ground]. That adds a lot of clarity and technical argument to our discussion. Julo
Excerpt of message (sent 29 January 2002) by Somesh Gupta:
> While I support a generic direct data placement model,
> the following are additional points for consideration for
> analysis of memory bandwidths and sizes.
> 1. A 10G link dropping packets will not do TCP at 10Gbps.
> The rate drops as the packet loss increases. I don't recall
> but Franco or Victor from Nortel had posted an equation once.
A very old (40 years?) rule of thumb is that 1% loss costs you 50% in
throughput. I expect that it gets a lot worse as links get faster.
> 3. The analysis of 10Gbps, half way round the world
> was initially used in this debate. ALthough interesting, the person
> with the scenario above is not going to blink at the cost of
> 256MBytes of fastest memory considering what they are paying
> for the link.
One reason ATM failed as a LAN is that its design was burdened with
complexity based on that sort of scenario. (In other words: "it has
to work at umpteen Gig, across the globe, and only use a tiny little
bit of memory because implementations can't handle a megabyte of
A design optimized for the combination of very high bit rate and very
long latency will inevitably be way overpriced for the predominant
case, which is the LAN case.
Last updated: Tue Jan 29 17:17:59 2002
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