I'm not very familiar with generic traffic shaping.
But, at first glance it looks like it is basically the same thing as frame
relay traffic shaping except that it does not dynamically change based on
network congestion because there is no method set up to notify the router of
any congestion encountered.
Using 'frame-relay traffic-shaping' indicates that the router can change the
traffic rate based on becns or foresight notifications of congestion. You
will have to use a 'frame-relay map-class' to tell the router how you want
to shape the traffic.
With generic traffic shaping you can specify the rate directly on the
interface because you do not need to tell it what sort of congestion
notification to listen to.
When you use the command 'frame-relay traffic-rate 64000 128000' (for
example) you get the following values -
mincir - 32000 - This is amount sent when congested
CIR - 64000 - This is the amount to send with no congestion
bc - 64000 - This is the amound to send per interval
be - 64000 - This is the burst amount to send in the first
interval
tc - 125 - This is the interval time in milliseconds
The router will send out traffic in the following pattern each second (for
tc=125 or 1/8 or a second) when there is no congestion
bc+be / bc / bc / bc / bc / bc / bc / bc
so for this config it would send -
128000 / 0 / 0 / 0 / 0 / 0 / 0 / 0
then it would repeat that for the next second.
By doing it like this the router attempts to send the full amount of traffic
every second.
You can go in and specify the Bc, Be, CIR, and mincir to be other values to
try and shape the traffic in different ways, but there is rarely any need
to.
For example, if you were to use the following config
map-class frame-relay test
frame-relay cir 128000
frame-relay mincir 64000
frame-relay bc 8000
frame-relay be 64000
you would get the following traffic pattern -
72000 / 8000 / 8000 / 8000 / 8000 / 8000 / 8000 / 8000
So, you would still get 128K in the one second.
The problem with this is that the router can only bust beyond Bc (up to
Be) when it has excess bandwidth available. So, if it keeps sending at 8000
then it will be at 64000 each second after that. Until it has transmitted a
second with less then 64000. Lets say in one interval it only transmitts
6000. So, next interval it was an excess of 2000 that it can transmit as
Be. This can continue until it was built up 64000 which is the max Be it
can ever have.
Its sorta like roll-over minutes for cellular phones :)
By using the the 'frame-relay traffic-rate xxx yyy' command you are fooling
the router into sending max Be every second. It thinks its Bc is 64000 so
the in the intervals it cant send traffic (because it hit line speed in the
first interval) it builds up credit again so it can burst at full Be on the
next seconds interval.
It really depends on how you want your traffic shaped and what sort of
applications are running over the link. But, if they aren't extremely time
sensitive, the generic command should work.
The one thing to watch for in the 'frame-relay traffic-rate xxx yyy' command
is that it assumes your mincir is 1/2 your average speed value. So, if you
set your average to your contracted CIR and the router encounters
congestion, it will slow down to the mincir which is half of that. To get
around this you can set your average speed to double your CIR.
If you order your CIR at 1/2 your line speed (128K port, 64K CIR) you can
use something like this 'frame-relay traffic-shaping 128000 128000'
The router will run at 128000 unless it hits congestion and then it will run
at 64000.
Hope that helps.
Mike
>
>Wizards,
>
>As the FRTS has been brought up here, I really want to
>take this chances to get some help from you in
>understanding this.
>
>When we enable the 'frame-relay traffice shaping'
>under the inferface, we start using frame-relay
>traffice shaping not generic shaping, right?
>
>in the map-class of frame relay, we can configure CIR,
>Bc and Be, how is this different from just configure
>'traffic-rate xx yy' in the map-class?
>
>As far as I understand, it is not quite effective to
>controll QoS in FR, I am not sure whether someones
>have seen some detailed perfermence comparation betwee
>two kinds of traffic shaping.
>
>Thanks
>
>Kent
>
>--- Michael Fountain <[EMAIL PROTECTED]> wrote:
> > The easiest way to do this is to only configure the
> > CIR and Line speeds and
> > let the rest default.
> >
> > Example commands -
> >
> > int s0
> > frame-relay traffic shapping #### Enable FRTS on
> > the interface
> > frame-relay class ExampleClass #### Shape as
> > defined in map class
> >
> > frame-relay map-class ExampleClass
> > frame-relay traffic-rate XXX YYY ### XXX =
> > CIR, YYY = Max Speed
> > traffic-rate adaptive-shaping becn #### Use
> > BECNs (not foresight)
> > #### for for
> > thottling
> >
> >
> > If you set XXX to 512K and YYY to port speed, he
> > will transmit at port
> > speed unless he receives BECNs from the network, and
> > then he will throttle
> > down to 512K.
> > If you set both XXX and YYY to 512K he will always
> > transmit at 512K
> >
> > Depending on your service provider and how
> > congested their network is you
> > may be able to go in and buy a small CIR like 64K
> > and then ignore that and
> > have your router set to send at 512K. If you do
> > that and some time in
> > future your SP starts dropping packets (because they
> > are over CIR) you will
> > have to go to them and buy up your contracted CIR,
> > but until then you can
> > save some money. We've been running AT&T Frame
> > Relay for a couple of years
> > and have yet to receive a single BECN.
> >
> > It is possible to go in and specify mincir, Bc,
> > Be, etc. But unless you
> > are going VOFR or some other application that has
> > specific needs using
> > generic FRTS will cover just about everything.
> >
> > Hope that helps,
> > Mike
> >
> >
> > >Guys,
> > >
> > >What are the parameters that I should configure on
> > the router to control
> > >the
> > >bandwidth usage of the user on a frame-relay
> > configuration.
> > >For instance, the user has T1 line and I need to
> > provide him only 512k. Is
> > >it the CIR, BE, BC, MINCIR, and traffic rate only ?
> > >and how do I calculate them ?
> > >
> > >Thanks a lot
> > >ME
> >
> >
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