Newsgroups: bit.listserv.big-lan
Date:         Tue, 29 Dec 1992 17:33:12 EST
From:         BIG-REQ@SUVM.BITNET
Subject:      BIG-LAN Digest, Volume 4, Number 86, Tuesday, December 29, 1992

BIG-LAN DIGEST          Tuesday, 29 December 1992      Volume 4 : Issue 86

Today's Topics:

                        Why just 30 thinnet nodes?
             Full Range of LAN Management Services from Wang
                            X.25 MULTIPLIXING
                          Multiplixing X.25 line

Moderated by John Wobus, Syracuse University

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----------------------------------------------------------------------

Date: Wed, 23 Dec 1992 11:53:08 +1000 (EST)
From: "Mark I. Williams" <M.Williams@cc.uq.oz.au>
Subject:      Why just 30 thinnet nodes?


>Does anyone know the reason that the maximum attachment is 30 for thin
>Ethernet/IEEE802.3?
>
>Please explain the reason.
>
>Soo N. Kim
>Goldstar Information and Communications

The reason for this comes from the method of attachment of devices to
10Base2 coax. Instead of having a tap for the transceiver, the re is an
actual T-junction. Now, for those of you who have done transmission line
theory, a T-junction is actually a stub. Now, when a stub reaches 1/4 of
the wavelength of the signal in length (I think it's a quarter), then the
reflections back from the end of the stub cancel the signal, which is not
what you want. From memory, the wavelength in 10base2 is about 8m, which
means that a 2m stub will be approximately tuned to flatten your network.

Now, These T-junctions are stubs of effective length about 2-3 cm, and I
am told that if you put a lot of small stubs on a transmission line, they
act something like one large stub the sum of the lengths of the short
stubs. That is, 30 hosts on a 10BASE2 segment is equivalent to a stub of
about 70cm. I suppose the folks on the IEE802.3 committee decided that
70cm was the maximum stub length that could be tolerated before the
reflections started causing too much distortion to the signal.

cheers,

Mark Williams         The University of Queensland       miw@cc.uq.edu.au
+61 7 36 54012   (w)  Prentice Centre
+61 7 36 54477  (fax) Qld 4072  Australia
nil sine magno vita labore dedit mortalibus.   -- Horace

-------------------------------------------------------

Date: Wed, 23 Dec 1992 16:54:01 GMT
From: ELAINE.DELOACH@OFFICE.WANG.COM ("Elaine Deloach")
Subject:      Full Range of LAN Management Services from Wang

Wang now offers a comprehensive suite of services to customers with large
LANs, providing cradle-to-grave LAN assistance.  LAN Management Services
are divided into three phases:

       Solution Development
       Solution Implementation
       Solution Support

With these services, customers can now look to Wang for the full range
of their enterprise-wide LAN needs: hardware, software and services.

Solution Development Services include:

   Business Needs Analysis to determine your business objectives for the
   network, develop a conceptual picture of the enterprise-wide LAN, and
   construct cost/benefit analyses.

   Workflow Analysis to determine which business tasks can be automated
   and how to implement them.

   Application Development Services create LAN based applications for
   large networks to address your specific business needs.

For more information on these and Solution Implementation or Support
Services, just send me an EMail request or call me at 508-967-3796.

Elaine.Deloach@OFFICE.Wang.com
FAX 508-967-7020

-------------------------------------------------------

Date: Thu, 24 Dec 92 09:37 GMT
From: KBARAKA@VRIT01.EG
Subject:      X.25 MULTIPLIXING

Hello,
My problem is that we have IBM x400 machine which connected to X.25 network,
and we are decided to install a 10Base-T network consisting of 3 PCs and One
   File Server which is a 486 machine with Eicon HSI X.25 adapter .
My question is there any way to use the same X.25 line which connected to the
   IBM X400 machine to use it on the 486 File Server to connect it to the Eicon
      HSI X.25 adapter.
The 486 File Server will be runing SCO UNIX operating system & HP Open mail.
and each PC will use SMC 10Base-T Ethernet card.
Any suggestions will be apprechiated....
Thanks.

-------------------------------------------------------

Date: Thu, 24 Dec 92 14:48 GMT
From: KBARAKA@VRIT01.EG
Subject:      Multiplixing X.25 line

Hello,
I need to know if I can used the same X.25 line to connect both AS400 machine
   and X.25 gateway on SCO UNIX Server connected to 10Base-T Ethernet network.
Note:
The AS400 machine is not connected to the Ethernet network.
Any suggestions in spliting X.25 line is apprechiated.
Thanks....

-------------------------------------------------------


End of BIG-LAN Digest
*********************
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