Date: Fri, 16 May 1997 17:27:36 -0400 (EDT) From: Chuck Robey <chuckr@glue.umd.edu> To: Mark Tinguely <tinguely@plains.nodak.edu> Cc: black@zen.cypher.net, sthaug@nethelp.no, hackers@FreeBSD.ORG Subject: Re: Why use ATM, (was Cluster Computing in BSD) Message-ID: <Pine.BSF.3.91.970516171733.7298E-100000@Journey2.mat.net> In-Reply-To: <199705162048.PAA19763@plains.nodak.edu>
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On Fri, 16 May 1997, Mark Tinguely wrote: > Steinar Haug says: > > I haven't seen any sign of inexpensive 155 Mbps ATM NICs, why do you > > think inexpensive 622 Mbps ones are coming soon? > > they are coming down in price, but not nearly low enough to be mainstream. > the cheapest cards are the ones that use host memory for packet segmentation > and re-assembly. I wish I had a performance study to see how much speed > is lost using host memory for SAR operations. > > Ben Black asks: > > and why would you want to use something as inefficient as ATM for a > > cluster interconnect? > > in-efficiency is not a concern problem IF the end result is faster than > anything else on the market. ATM, lost that window of opportunity and today > is not the fastest thing on the market because everone wants IP. I think even > Sonet PPP/frame relay will upstage ATM. This confuses me somewhat. Let me detail what confuses me. You say that ATM is losing out to ip and (perhaps) to Sonet. This is juggling the protocol levels badly in my mind, because SONET is a link level protocol (so it isn't encapsulateable by anything), while ATM isn't, it needs a link level protocol to ride on. What I'm saying, is I don't think that ATM can be in competition with SONET; that's why your statement confuses me. On top of that, I thought that ATM was being used as a way to link LANs, so ip would be routed over ATM links, and again, not competitive. You could conceivably have a SONET link that had an ATM constituent, which was carrying an ip message inside it. That's the way I understood it, and that example was (supposedly) fairly common, at least as common as SONET itself is. Where am I wrong? > > yeah, this prob. belongs in -chat or -atm. > > --mark. > > ----------------------------+----------------------------------------------- Chuck Robey | Interests include any kind of voice or data chuckr@eng.umd.edu | communications topic, C programming, and Unix. 9120 Edmonston Ct #302 | Greenbelt, MD 20770 | I run Journey2 and picnic, both FreeBSD (301) 220-2114 | version 3.0 current -- and great FUN! ----------------------------+-----------------------------------------------
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