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Re: (ASCEND) MAX 4004> Seeing Data Rate of 31200 after changing to 33.6
Kevin Smith wrote:
>
> At 03:04 PM 5/19/97 -0400, Neil Movold wrote:
> >I have recently changed my configuration under 90-800 Mod Config/Tserv
> >options/Max Baud from 28800 to 33600 in order to see if our 33.6
> >customers could work at higher speeds than 28.8. Since the change on
> >both of my maxen, I have seen customers get data rates of 31200. Is this
> >normal? The cards are both the MOD-8 and MOD-12 cards. Should I not
> >expect to see data rates of 33600? Is this a hardware limitation?
>
> Over the last few weeks I've seen postings of connect rates and %ages
> of each. In al examples there were 33.6 connects in the low %ages. Hence
> this is not a hardware limitation. You may find you have less success with
> CT1 lines than PRI - just from experience....
After talking with other Ascend reps out in the field as well as other
ISPs who
use the Ascends, the consensus is as you speak. PRI lines are more
efficient
than CT1 lines at providing reliable bandwidth. Also, people must
realize the
difference between a supplied CT1 line that is on the line side vs the
trunk
side of the CO switch, with the trunk (digital) side being more
efficient. With
the ability to only require one channel of a PRI for signalling for
multiple
PRIs on the same box, you only loose one modem from user availability.
This is
not so bad. Many people, me included have gone the CT1 route to
maximize the
modem density on each MAX. There are pros and cons to this approach.
All my
future maxen will be using PRI.
>
> >From a marketing perspective, the 31200 speeds is more than the 28800,
> >although not by much, and can be marketted as a speed improvement to the
> >customer base.
>
> I think *all* modems are labelled with "up to XXX speed", are they not?
> ^^^^^
Absolutely right. What is even more ironic is that the local Telco even
has
printed in their phone book that they will guarantee up to 2400 baud.
This is
mostly due to the age of a lot of the copper that goes out form the
local
exchanges to the customer premiss. This is usually the gotcha for most
users
and the technical papers that Ascend has about identifying poor phone
lines
is very helpful. The modemdiag statistics in debug mode are also
revealing
about how good the line quality is to the remote end of the customer
equipment
and will assist administrators in determining if there is problems with
their
side.
> >What about these K56FLEX cards at lower speeds with heat etc as
> >problems? I have seen before on the list that the boxes can only handle
> >48 56Kb modems do to heat etc.
>
> Heat is less of an issue with the new cards than the old ones, and there
> is NO such limitation in the MAX400X. The MAX4048 is only allowed to
> carry 48, so maybe that caused some of the confusion.
>
> > However, if the maxen were configured to
> >only handle speeds to 33600, would that have any affect on the heat
> >problems and thus allow for a full 72 modems in a 4004 chassis? The
> >thought here is to take advantage of the K56FLEX Upgrade plan to replace
> >the recently purchased MOD-12 28.8 modems with the newer 56Kb modems in
> >order to take advantage of the better performance of the new cards.
>
> The MAX400X will happily take 72 modems, and you should use your own
> data to determine the "performance" improvement (having read so many
> performance reviews that are outright contradictory with each other).
>
Even though there have been contradictory performance reviews of the new
cards, if you are going to keep your line speeds at 33.6, it makes sense
to upgrade to the new K56FLEX cards, either through the free upgrade or
the normal upgrade. With the processors now being loaded on each card,
and the fact that the hardware can handle the 33.6 speeds more
efficiently
than the older MOD-8/12 cards, users will surely get better performance.
>From the Ascend field reps and other ISPs, including UUNET who are
deploying
TNTs everywhere, the consensus is that the above case is true.
One thing to note is that in order to use the K56FLEX cards at 56Kb
speeds,
you must use a PRI vs a CT1 line. Using the cards for 33.6 speeds, you
can use
the currently installed CT1 lines.
Thanks for you comments Kevin. Your active participation within this
list has
definitely made a difference to many of the Ascend product users. I
commend
you on your efforts with great appreciation. Tell you boss I said you
need
a raise. :-)
> Kevin Smith Updated Service and Support
> Ascend Communications Resources are now at:
> http://www.ascend.com/service
--
Neil Movold Tel: +1 441-296-1800 x 28
Director of Technology Fax: +1 441-295-1149
Internet (Bermuda) Limited http://www.ibl.bm
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