dave@stcns3.stc.oz (Dave Horsfall) (02/09/88)
There has been quite a bit of publicity lately in this medium on the
"Telebit Trailblazer" (R). While it appears to run quite well on
certain arcane half-duplex protocols which I need not mention :-),
I am wondering how it performs on real full-duplex protocols.
Methinks it would lose quite a bit of its claimed throughput...
The cogniscenti will realise I am referring to the protocol in use
at most Australian sites, called variously ACSnet or SUN-III. Actually,
ACSnet is the network itself, using the SUN-III software. Anyway, it's
a full-duplex multi-stream protocol, so a quick estimate suggests that
you will get vastly less than the half-duplex throughput. Especially
if the modem doesn't support SUN-III spoofing *-)
No - I'm not knocking the 'Blazer. I'm just concerned that should
my company go out and buy a couple, it won't perform anywhere near
as well as suggested, because we talk a different language!
Anyone tried the 'Blazers on protocols other than UU**?
Oh yeah - almost forgot. Saw several ads in the local computer
gutter press here, about the "NetComm (The Australian Company)
Trailblazer". You know - its specs look remarkably like those of
another modem with a similar name ??!! Wonder if it's no more than
a foreign import, with a local line interface?
And has anyone commented on someone's opinion (can't remember who,
grovel grovel) that said words to the effect that 'Blazers appear
to be more cost-effective than X.25? We're pretty remote here,
down-under, hence the interest... Land of the Long White Cloud,
are you listening too?
--
Dave Horsfall (VK2KFU) ACS: dave@stcns3.stc.OZ.AU
Alcatel-STC Australia ARPA: dave%stcns3.stc.OZ.AU@uunet.UU.NET
11th Floor, 5 Blue St UUCP: {enea,hplabs,mcvax,uunet,ukc}!\
North Sydney NSW 2060 AUSTRALIA munnari!stcns3.stc.OZ.AU!davejohn@basser.oz (John Mackin) (02/10/88)
In article <231@stcns3.stc.oz> dave@stcns3.stc.oz (Dave Horsfall) writes: > I am wondering how [the Trailblazer] performs on real full-duplex protocols. > Methinks it would lose quite a bit of its claimed throughput... It does. We tried a pair between here and the University of Queensland last year. The best we could get was about 100 characters/sec (as shown by linkstats -V), i.e. far short of normal 1200 baud modems. [I say _far_ short, just so there's no confusion, because these are full duplex protocols we're talking about, not half duplex -- with V.22 modems on a normal telephone connection, we get data rates in the region of 220-230 characters/sec, assuming there is data to be transferred both ways.] They're no use if they don't understand your protocol. Now, for interactive use, if you could afford them they'd be wonderful -- the echo delay was noticeable but not massively annoying, and the speed was terrific! > No - I'm not knocking the 'Blazer. I'm just concerned that should > my company go out and buy a couple, it won't perform anywhere near > as well as suggested, because we talk a different language! Absolutely right. Piers made vague noises at the time about doing a protocol module for them, but unless and until that happens, they're no good for Sun III. (Or Sun IV for that matter.) > Saw several ads in the local computer gutter press here, about the > "NetComm (The Australian Company) Trailblazer". [...] Wonder if it's > no more than a foreign import, with a local line interface? That's way we tried, and yes, that's what it is. John Mackin, Basser Department of Computer Science, University of Sydney, Sydney, Australia john@basser.oz.AU (john%basser.oz.AU@UUNET.UU.NET) {uunet,hplabs,mcvax,ukc,nttlab}!munnari!basser.oz!john
john@basser.oz (John Mackin) (02/10/88)
In article <1187@basser.oz>, I wrote: > We tried a pair [of Traiblazers] between here and > the University of Queensland last year. The best we could get was > about 100 characters/sec [...] i.e. far short of normal 1200 baud modems. > [...] Piers made vague noises at the time about doing > a protocol module for them, but unless and until that happens, > they're no good for Sun III. (Or Sun IV for that matter.) Piers responded with the following, which he asked me to post: From piers@cluster.cs.su.oz Wed Feb 10 09:16:12 1988 To: john.basser Subject: trailblazer modems and Sun4 The new Sun4 protocol will drive trailblazers flat-out in both directions, since it is designed to work in such conditions, and consists of two de-coupled half-duplex protocols driven by separate processes (ie: the protocol will not be affected by sub-protocol buffering, the problem with the Trailblazer, and CSIRONET, for that matter.) So, that's all you have to do, just wait for Sun IV to come out. And in case you're wondering when that will happen, Piers says ``it's still on schedule'' -- meaning that will go into alpha testing at the end of March. I know it's doing something, I get the occasional badhandler message from it :-). John Mackin, Basser Department of Computer Science, University of Sydney, Sydney, Australia john@basser.oz.AU (john%basser.oz.AU@UUNET.UU.NET) {uunet,hplabs,mcvax,ukc,nttlab}!munnari!basser.oz!john
pjh@mccc.UUCP (Peter J. Holsberg) (02/16/88)
In article <231@stcns3.stc.oz> dave@stcns3.stc.oz (Dave Horsfall) writes: |Anyone tried the 'Blazers on protocols other than UU**? I've used one with a hayes 2400 and zmodem protocol, and consistently get 235+ cps. But that's probably not what you're asking, right? -- Peter Holsberg UUCP: {rutgers!}princeton!mccc!pjh Technology Division CompuServe: 70240,334 Mercer College GEnie: PJHOLSBERG Trenton, NJ 08690 Voice: 1-609-586-4800
dave@stcns3.stc.oz (Dave Horsfall) (02/22/88)
In article <216@mccc.UUCP> pjh@mccc.UUCP (Peter J. Holsberg) writes: >In article <231@stcns3.stc.oz> dave@stcns3.stc.oz (Dave Horsfall) writes: >|Anyone tried the 'Blazers on protocols other than UU**? > >I've used one with a hayes 2400 and zmodem protocol, and consistently >get 235+ cps. But that's probably not what you're asking, right? Not exactly, no. I was interested in Blazer/Blazer comms on full duplex protocols. The replies I received all indicate they behave terribly, worse in fact than using a "straight" modem. -- Dave Horsfall (VK2KFU) ACS: dave@stcns3.stc.OZ.AU Alcatel-STC Australia ARPA: dave%stcns3.stc.OZ.AU@uunet.UU.NET 11th Floor, 5 Blue St UUCP: {enea,hplabs,mcvax,uunet,ukc}!\ North Sydney NSW 2060 AUSTRALIA munnari!stcns3.stc.OZ.AU!dave