From: The Great Ryan (pv.ryan@gmail.com)
Date: Tue Oct 11 2005 - 12:09:45 GMT-3
yes. I'm surprised when i'm reading a QoS book that Tp is checked
before Tc. Besides, I also find that if size of packet < Tc (i.e.
conform), it will deduce tokens on both Tc and Tp. ooo.. cool !
Thanks for your previous reply as you teach me some baselines on QoS.
Ryan
2005/10/11, Chris Lewis <chrlewiscsco@yahoo.com>:
> Q1, optimizing the depth of the token bucket depends on the profile of the
> incoming traffic, out of scope for the lab. Generally, if you have large
> bursts, you get better throughput with a seeper bucket, smaller bursts, it
> is better with a shorter bucket.
>
> Q2, Don't try to memorize everything, spend time working out quick ways to
> verify these things. Even if you do memorize everthuing, you can't keep up
> with IOS changes. So apply the policy-map to an interface and run the show
> policy-map interface command to see the answer as follows:
>
> Router1(config-if)#do sho policy-map int
> Serial3/0
> Service-policy output: test
> Class-map: class-default (match-any)
> 20 packets, 1682 bytes
> 5 minute offered rate 0 bps, drop rate 0 bps
> Match: any
> police:
> cir 8000 bps, bc 1500 bytes
> pir 16000 bps, be 1500 bytes
> conformed 1 packets, 44 bytes; actions:
> set-prec-transmit 5
> exceeded 0 packets, 0 bytes; actions:
> set-prec-transmit 1
> violated 0 packets, 0 bytes; actions:
> drop
> conformed 0 bps, exceed 0 bps, violate 0 bps
>
> Q3. Operation is described at
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123tcr/123tqr/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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