Just to add a point to Priscilla's excellent explanation - in one sense,
you don't implement "queueing technologies". If a packet has to wait to be
transmitted, it will be queued (or dropped, if you have nowhere to queue
it).
What you can configure is not really how the packets are queued, but how
they are de-queued. You can let it default (in which case it will either
use First In First Out (FIFO) queueing, or Weighted Fair Queueing,
depending on the interface), or you can configure what Cisco seems to call
"fancy queueing", which means priority queueing, custom queueing, or
anything else other than the default.
If it's a "fast" link, then the extra processing time taken to classify the
packets and de-queue them in the correct order outweighs the time they
would be waiting - it's generally quicker to just do FIFO queueing.
However on a "slow" link the benefits of implementing some form of
prioritisation are a lot greater. The definition of "slow" and "fast" has
been changing over time - I seem to recall that Cisco used to recommend
that queueing be allowed to default on links with a speed greater than 512
Kbps.
And regarding the modem question, I'm no modem guru but I think it's AT&F
to load the factory configuration.
JMcL
---------------------- Forwarded by Jenny Mcleod/NSO/CSDA on 31/07/2001
04:05 pm ---------------------------
"Priscilla Oppenheimer" @groupstudy.com on 31/07/2001
03:27:15 am
Please respond to "Priscilla Oppenheimer"
Sent by: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
cc:
Subject: Re: Queuing and Modem [7:14103]
Think about what the word "queue" means, which I realize is not easy if you
are not a native English speaker. Websters dictionary says it means, "a
waiting line especially of persons or vehicles." In England, I think people
even say that, "I'm waiting in a queue at the grocery store," or whatever.
In the U.S. we say "I'm waiting in line," except in New York, where they
say, "I'm waiting on line." (New Yorkers are different. ;-)
Ideally, packets shouldn't wait in line at all. They should whip through
the router and zip out the interface as quickly as possible. But if the
router is slow, or of more relevance, if the interface is slow, the packets
pile up in a queue. On a 56-Kbps line, for example, only 56 K bits can go
out per second. Sending a whole packet takes time. Other packets must wait.
If packets are waiting in a queue, you can configure the router for
something other than First In First Out. You can configure the order in
which packets should be removed from the queue and transmitted. The order
can be based on policies related to performance, security, etc. So, for
example, you could say SNA should be dequeued and transmitted before FTP.
Priscilla
At 09:22 PM 7/29/01, Hunt Lee wrote:
>It would be very great if someone can shed some light on this. It's a
>little bit off topic but thanks :) Firstly, when should one implement
>queuing technologies? I have read from various source saying that only
>do so if it is a bursty WAN links with T1/E1 speed or lower that
>experience temporary congestion? Is this true?
>
>Secondly, what AT commands should I use to set my modem back to default
>settings?
>
>Thanks again.
>
>Regards,
>Hunt Lee
>IP Solution Analyst
>Cable and Wireless
________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
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