REPLYS TO SATELLITE GATEWAYS


Jean-Pierre Dumas (DUMAS@SUMEX-AIM.STANFORD.EDU)
Tue 24 Feb 87 01:19:53-PST


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Date: Tue, 3 Feb 87 12:05:37 pst
From: Robert Michaels <michaels%hplrkm@hplabs.HP.COM>

Hi:

I saw your message on the TCP-IP mailing list asking about experiences
with satellites. We recently made use of a satellite link to connect
IP networks which I think may be of interest.

Our Internet:

HP has built a small internet using cisco AGS gateways equipped with
their 56Kbit serial interface. The network connects divisions in the
bay area via HP's Bay Area Microwave network. It also ties in divisons
in Oregon and Colorado via a 56kbit channels on our leased T1 lines.
In Palo Alto the various buildings are interconnected via a broadband
system.

The Satellite Link:
It was the above network we wanted to connect to the show network at the
UniForum trade show in Washington DC two weeks ago. We contracted VitaLink
to provide the dish and technician at the convention and used HPs own
equipment here in Palo Alto. The link was 56Kbit, running on KU band.
In Palo Alto we have a 3.7m dish and at the convention they used a 1.8m
dish. All hardware including modems and RF amp are built by Vitalink.
The modems have a simple V.35 connection - which meant all we had to do
was convert the V.35 to RS232 so it could connect to the cisco AGS.
The link worked very well - delay was not objectionable. The only problem
we had was snow, however, VitaLink has a dial in system via land lines
to their modems and was able to detect the attenuation of the signal and
alert the technician to sweep out the dish. (permanent installations have
shields to protect against snow and ice).

About the cisco boxes:

The access control features of the gateway were very useful in controlling
who had access to our internet. The lack of a V.35 interface is annoying
but Black Box makes a good little hack. I see this TransLAN (DEC Bridge100)
thing as a major loose. At the convention we also used a 9600 baud dial
up modem as a back-up if the satellite link failed. We ran both links
simultaneously - something we could never do with TransLAN. Well, that's
not true, we could connect both links but TransLAN would detect the a
"loop" and promptly shut down one of the links.

Hope this is of interest to you.

Regards,
Robert Michaels
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        +--------------------------------------------------+
        | Gerard H. Gaye |
        | CEN Saclay |
        | |
        | | gaye@frsac11 (bitnet) |
        | gaye%frsac11.bitnet@wiscvm.wisc.edu (arpanet) |
        | |
        | also: dumas@sumex.stanford.edu |
        +--------------------------------------------------+
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