Path: utzoo!attcan!uunet!decwrl!bacchus.pa.dec.com!shlump.nac.dec.com!wizzle.enet.dec.com!mack From: mack@wizzle.enet.dec.com (Dick Mack) Newsgroups: comp.dcom.lans Subject: Re: "real-time" over a lan: token ring vs ethernet vs ? Keywords: real-time, token ring, 802.5, ethernet Message-ID: <14618@shlump.nac.dec.com> Date: 15 Aug 90 18:56:35 GMT References: <1350@berlioz.nsc.com> <19300@well.sf.ca.us> <61624@bu.edu.bu.edu> Sender: newsdaemon@shlump.nac.dec.com Reply-To: mack@wizzle.enet.dec.com (Dick Mack) Distribution: comp Organization: Digital Equipment Corporation Lines: 22 |> |> Also, it was mentioned that "the token is believed to be lost" when a new |> station inserts and clicks in its MAU relay, thus causing longish delay. |> This is not what the protocol specifies; the Initialisation Phase merely |> causes the new station to exchange special MAC frames with designated |> Server nodes on the ring. At any rate, there should be no loss of token |> *theoretically*. |> -- |> ........................................................................... |> Andrew Palfreyman Incidentally, in English, the name of the planet |> andrew@dtg.nsc.com is "Earth". - Henry Spencer |> If what you are talking about here is 'graceful insertion', one has to be careful - even a single attachment end station can add enough delay to blow timers and cause a ring re-initialization. When one takes into consideration that two operational segments might be joined, then there has to be some guarantee that there are no multiple tokens and that the insertion has not caused frames to be concatenated. Ensuring token loss so that the total ring reconfigures is an easy way to accomplish this. Dick Mack