From: The Great Ryan (pv.ryan@gmail.com)
Date: Tue Oct 11 2005 - 22:58:39 GMT-3
when the 900byte packet pass the police, it will use the exceed bucket
token. Hence, the token left in exceed bucket is 100bytes.
when time passed 0.40second, the system will gain 400bytes and only
200bytes can be put on conform backet (because the total size is
1000bytes only), Thus, the rest will be put on exceed bucket and it
finally get 100+200 in token size.
Ryan
2005/10/12, Ivan Kuchin <ivan@iip.net>:
> After reading this doc. I have some question from "Example: Token Bucket
> Algorithm with Two Token Buckets Example" police command.
>
> "If the next packet arrives 0.40 seconds later, 400 bytes are added to the
> token buckets ((.40 * 8000)/8). Therefore, the conform token bucket now has
> 1000 bytes (the maximum number of tokens available in the conform bucket) and
> 200 bytes overflow the conform token bucket (because it only 200 bytes were
> needed to fill the conform token bucket to capacity). These overflow bytes
> are placed in the exceed token bucket, giving the exceed token bucket 300
> bytes."
>
> Why at exceed token bucket 300 bytes free ? What does it mean "overflow bytes
> are placed in the exceed token bucket" ?
> I think that after 0.4 sec conform token bucket must have 1000 bytes free and
> exceed token bucket must have 500 bytes free.
> How 200 byte moved from conform to exceed token bucket ?
>
>
> > Q3. Operation is described at
> > http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123tcr/123t
> >qr/qos_o1gt.htm#wp1084420
> >
> > The key point you should take away for your question is that the incoming
> > packet is first measured against the tokens in the Tp bucket, which is set
> > by the Be parameter. This is kind of counter intuitive, normally we think
> > of things being measured against the committed rate first, then if they
> > exceed, being measured against the exceed bucket, but that is not the case
> > for the two rate policer.
> >
> > Chris
> >
> > The Great Ryan <pv.ryan@gmail.com> wrote:
> > Hi Group,
> >
> > I read the document and understand that in police command that Bc is
> > the Token Bucket size in policer and CIR is the rate of filling Token
> > in Token Bucket
> >
> > (Q1) CIR & Bc
> > =========================
> > i.e. police 128000 16000
> > It means that the Token Bucket depth is 16000byte and the filling rate
> > 128000bps such that it take one second to fill up the bucket.
> >
> > I want to know if it is meaningful that I set
> > "police 128000 20000" => larger bucket, or
> > "police 128000 10000" => smaller bucket ?
> >
> >
> > (Q2) CIR & PIR
> > =========================
> > If I set the following:
> > police cir 64000 pir 128000
> > conform-action set-prec-transmit 5
> > exceed-action set-prec-transmit 1
> >
> > Since I haven't set the violate-action, it will drop all packets if
> > the rate is above 128kbps
> >
> > If now I have 256kbps rate passing through the policer, will the
> > result be the following:
> > - first 64kbps marks as precedence 5 and transmit
> > - next 64kbps marks as precedence 1 and transmit
> > - last 128kbps drop
> >
> > Am I right ?
> >
> >
> > (Q3) CIR, Bc and Be
> > =========================
> > If I set the following
> > police cir 128000 bc 16000 be 8000
> > In the situration that , at time T= 0ms, traffic flow such that Bc is
> > empty and the next packet (size = 1500byte) use Token in Be. After
> > sending this packet, the time is T1= 5ms. The Token gain in this
> > period= 128000*0.005/8 = 80byte. I want to know this token will be
> > put on Bc or Be ? If the next packet size is 100 byte, it will use Bc
> > or Be ?
> >
> >
> > Thanks a lot !
> > Sorry if I have any mistake/mis-understanding.
> >
> >
> > Ryan
> >
> > _______________________________________________________________________
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> >
> >
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> --
> iWAN kU^IN (mail to: ivan@iip.net)
> NOC iip.net
> 137-31-04
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