From: Fernando Carvalho (fernando.cagica@t-online.de)
Date: Fri Feb 29 2008 - 07:59:41 ARST
Just want to add one thing to what Shiran said:
By allowing BE you are allowing your pvc to use in the present time slot the
bandwidth that was not used in the previous one, but this is also going to
make your network load more unpredictable. See it like this: If all (or at
least a big number of) users in one Frame-relay network in some time slot
send traffic using the BE you will have a peak of traffic eventually above
the capacity of some FR links at the provider which depending how the
provider handles overload can lead to loss of traffic or delay/jitter. None
of it good for the users that are transmiting sensitive (eg. Real-time)
traffic.
Cheers,
-----Urspr|ngliche Nachricht-----
Von: nobody@groupstudy.com [mailto:nobody@groupstudy.com] Im Auftrag von
shiran guez
Gesendet: Freitag, 29. Februar 2008 09:14
An: Donghai Zhang
Cc: CiscoQ'O0Wi
Betreff: Re: how to comprehend Bc and Be
QoS is a very general name, BC and BE value mainly relate to the Shaper is
one of the tools in your tool belt, there is also Policer and congestion
management / avoidence, LFI, also you have what Cisco call Signaling (RSVP).
now to your specific question:
BC is the amount of data you are allowed to send each TC (Time Interval),
when using the sharper we divide the second 1000ms to several time intervals
and each time interval we are allowed to send a specific amount of data, so
from that you can understand that when you take the the BC and multiply by
the TC you get your BW per second or your CIR.
BE is the amount of data you are allowed to burst above the BC, but now you
should ask your self if I am bursting above the BC am I actually getting
more traffic?! so the answer is no, as you are allowed to Burst only if you
have not sent in one of the intervals or you sent less data in one of the
intervals only then you are allowed to exceed the BC and by doing that you
"regain" the BW you paid for.
The concept is a little confusing at first glance but once you understand
that it is becoming really easy.
I hope that helped,
On Fri, Feb 29, 2008 at 4:28 AM, Donghai Zhang <zdh1207@gmail.com> wrote:
> Dear all,
> I am sometimes puzzled that when I use QoS tools to condition net
> traffic. That is, what is the use of Bc and Be? It seams that these
> two parameters can be set wilfully. Is that corret? thanks .
>
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-- Shiran Guez MCSE CCNP NCE1 http://cciep3.blogspot.com http://www.linkedin.com/in/cciep3
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