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Posted by KM on January 30, 2006, 11:57 am
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I mean really slowing ethernet down.
I have a requirement to slow down ethernet so the clock speed is running at
about 100kHz. Everything else should work as is, ie all the usual TCP/IP
protocol stuff.
There will no more than about 8 hosts on this slow network.
The purpose is to remove as much RF interference as possible, bandwidth is
not a problem - small infrequent packets.
The server will have a NIC, the hosts will terminate in PiC devices
emulating ethernet
My initial thought would be to have a modified server NIC and then a
hardwired hub.
Has anyone done this before? I have googled but been singularly unsuccesful
with this.
Regards
Martyn
--
===========================
Martyn Kinder G0CZD
Open-Xchange 0.8b5
http://www.czd.org.uk
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Posted by Walter Roberson on January 30, 2006, 3:41 pm
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>I mean really slowing ethernet down.
>I have a requirement to slow down ethernet so the clock speed is running at
>about 100kHz. Everything else should work as is, ie all the usual TCP/IP
>protocol stuff.
>There will no more than about 8 hosts on this slow network.
>The purpose is to remove as much RF interference as possible, bandwidth is
>not a problem - small infrequent packets.
An unusual requirement, but I can see how it might be useful in
some situations.
Would it perhaps be practical in the situation to use multidrop
RS422 (serial) instead of ethernet?
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Posted by Al Dykes on January 31, 2006, 7:22 am
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>>I mean really slowing ethernet down.
>
>>I have a requirement to slow down ethernet so the clock speed is running at
>>about 100kHz. Everything else should work as is, ie all the usual TCP/IP
>>protocol stuff.
>
>>There will no more than about 8 hosts on this slow network.
>
>>The purpose is to remove as much RF interference as possible, bandwidth is
>>not a problem - small infrequent packets.
>
>An unusual requirement, but I can see how it might be useful in
>some situations.
>
>Would it perhaps be practical in the situation to use multidrop
>RS422 (serial) instead of ethernet?
What kind of RF environment are you dealing with?
How do you know your network problems are RF-related?
What king of hub/switch do you have? What distances?
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore.
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Posted by Rick Jones on January 30, 2006, 4:43 pm
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> I mean really slowing ethernet down.
> I have a requirement to slow down ethernet so the clock speed is
> running at about 100kHz. Everything else should work as is, ie all
> the usual TCP/IP protocol stuff.
> There will no more than about 8 hosts on this slow network.
> The purpose is to remove as much RF interference as possible,
> bandwidth is not a problem - small infrequent packets.
I think someone else suggested multi-drop - or, you could just run a
bunch of plain pt-pt PPP links between the systems, and run an IP
routing protocol to deal with occasional link failures. You could use
heavily shielded serial cables and run them just about as slow as you
please.
Are you worried about RF from the wire, or from the NIC itself? If
not from the NIC itself, why not just run ethernet over fibre and
stick with COTS kit?
> The server will have a NIC, the hosts will terminate in PiC devices
> emulating ethernet
Not entirely sure if that nixes the idea of fibre or not.
rick jones
--
oxymoron n, commuter in a gas-guzzling luxury SUV with an American flag
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...
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Posted by William P.N. Smith on January 30, 2006, 7:09 pm
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>I have a requirement to slow down ethernet so the clock speed is running at
>about 100kHz.
>The purpose is to remove as much RF interference as possible
It's not the clock speed that causes the interference, it's the
rise-time of the signals.
IMHO, this is going to be really difficult to do, as all of your
backoff, retry, and other timing algorythms are going to have to be
redone. You are going to need to engineer, build, and maintain your
own NICs, hubs/switches, and client devices.
Why not use Rick's suggestion of fiber?
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