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Routers/back to back/V.35/Bandwidth

 
 
Baruah
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      03-03-2006
Hi,
I would like have some advice regarding connecting 2 routers back
to back using V.35 interface. How much bandwidth I can attain in this
manner ? Is it possible to get beyond 2Mbps !! and is it ok if I use
this configuration in a production environment ?

Can someone please give a few pointers regarding the
issue ?

Thanks in advance.

BB

 
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ciscodagama@gmail.com
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      03-03-2006
It looks like you can go up to 4 Mbps with V.35 though that is more
than the recommended maximum.

Take a look at

http://www.cisco.com/univercd/cc/td/...#xtocid2904339

Cisco da Gama
http://ciscostudy.blogspot.com

 
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Charlie Root
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      03-03-2006
<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) ups.com...
> It looks like you can go up to 4 Mbps with V.35 though that is more
> than the recommended maximum.
>
> Take a look at
>
> http://www.cisco.com/univercd/cc/td/...#xtocid2904339
>


According to this page recommended maximum is only 48Kbps, which is really
low. I suspect this is an old document (for Cisco 7000 platform). I've been
using V.35 interfaces for 2Mbps connections routinely for past 10 years
without problems. Also the newer documents do mention speeds that are much
higher than those humble few Kbps:

http://www.cisco.com/en/US/customer/...800b0858.shtml

So back to original question - one can get up to 8Mbps over V.35 connection,
but it depends on the hardware configuration.

Kind regards,
iLya


 
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steve_schefter@hotmail.com
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      03-03-2006
Charlie Root wrote:
> According to this page recommended maximum is only 48Kbps, which is really
> low. I suspect this is an old document (for Cisco 7000 platform). I've been
> using V.35 interfaces for 2Mbps connections routinely for past 10 years
> without problems. Also the newer documents do mention speeds that are much
> higher than those humble few Kbps:


I suspect that the recommendation they speak of is not Cisco's, but
the CCITT's. The V.35 spec actually calls out only one speed of use:
48K. But as you say, well beyond that is no problem (and very
common) for V.35. In general, for differential signals like V.35 and
RS-422, the shorter the distance and lower capacitance of the cable,
the faster you can go.

So the OP won't run into an electrical limitation. That leaves the
question of what the serial port can handle, which is also not
likely to be a issue.

Steve

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Steve Schefter phone: +1 705 725 9999 x26
The Software Group Limited fax: +1 705 725 9666
642 Welham Road,
Barrie, Ontario CANADA L4N 9A1 Web: www.wanware.com

 
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Baruah
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      03-03-2006
Thank you all for you comments. So, in summary we can use back to back
configuration and depanding upon the distance and lower capacitance of
the cable, and the hardware capability of the routers. I guess its not
of a issue if one of the router is of NOT cisco make.

-BB

 
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Peter
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      03-03-2006
Hi Steve,

> Charlie Root wrote:
> > According to this page recommended maximum is only 48Kbps, which is really
> > low. I suspect this is an old document (for Cisco 7000 platform). I've been
> > using V.35 interfaces for 2Mbps connections routinely for past 10 years
> > without problems. Also the newer documents do mention speeds that are much
> > higher than those humble few Kbps:

>
> I suspect that the recommendation they speak of is not Cisco's, but
> the CCITT's. The V.35 spec actually calls out only one speed of use:
> 48K. But as you say, well beyond that is no problem (and very
> common) for V.35. In general, for differential signals like V.35 and
> RS-422, the shorter the distance and lower capacitance of the cable,
> the faster you can go.
>
> So the OP won't run into an electrical limitation. That leaves the
> question of what the serial port can handle, which is also not
> likely to be a issue.


This brings up memories of 2 unrelated (but similar) situations that I
ran into with V.35 in 1996. We had been using V.35 at 2Mb for many
years, and in one situation we ran into an issue with a new V.35
connection between an IBM 3746 and Cisc 4700 Router (the 4700 was
providing clocking) . If I remember correctly, the Cisco 4700 Docs of
the time suggested that ~35ft was the maximum distance recommended,
whereas the IBM Docs suggested that 50ft was fine (using IBM cable of
course). We tried several local "tricks" to get this working over 45ft
of cable but had regular errors (at a fairly low rate) at the 4700
end. Eventually we were able to shorten the cable to about 36ft and it
all ran clean.

However this got us interested because we had never seen any issues
with 2Mb at 50ft, and theoretically, you probably could run 100Mb over
V.35, provided the cable length was short enough. Our research turned
up a little known fact that the particular model of serial port card
(I cannot remember what exact 4700 Serial card it was, except it had 6
ports on it) we were using in the 4700 had a "known cable length
limitation", and that testing with a different Serial card the 4700
worked fine at 2Mb over 50ft.

So there are the published specs and each manufacturers implementation
of those specs.........

Cheers.................pk.


--
Peter from Auckland.
 
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