RE: CBWFQ - Reseving BW for Voice

From: David Bartlett (David.Bartlett@reuters.com)
Date: Wed Oct 22 2003 - 13:52:42 GMT-3

Jason

Following link has info on the bw allocation using LLQ:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/
fqos_c/fqcprt2/qcfconmg.htm#1001291

Also, the following link has a very good explanation:

http://www.cisco.com/en/US/tech/tk543/tk757/technologies_tech_note09186a
0080103eae.shtml

David

-----Original Message-----
From: Kleberg, Jason [mailto:JKleberg@glhec.org]
Sent: 22 October 2003 17:37
To: David Bartlett; Cristian Henry H; Ken.Farrington@barclayscapital.com
Cc: ccielab@groupstudy.com
Subject: RE: CBWFQ - Reseving BW for Voice

Could someone please post a working example and some gotcha's on this?
Or at least a link where definitive answers exist.

thank you
jason

-----Original Message-----
From: David Bartlett [mailto:David.Bartlett@reuters.com]
Sent: Wednesday, October 22, 2003 11:25 AM
To: Cristian Henry H; Ken.Farrington@barclayscapital.com
Cc: ccielab@groupstudy.com
Subject: RE: CBWFQ - Reseving BW for Voice

Cristian

If you set max-reserved-bandwidth to 85% as you suggested you won't be
able to apply the policy because the policy has allocated 90% of
available cct bandwidth. The max-reserved-bandwidth configures the
total amount of bw you can allocate across all classes + the priority
queue.

David

-----Original Message-----
From: Cristian Henry H [mailto:chenry@reuna.cl]
Sent: 22 October 2003 16:06
To: Ken.Farrington@barclayscapital.com
Cc: ccielab@groupstudy.com
Subject: Re: CBWFQ - Reseving BW for Voice

Is my opinion the following:

Total bandwidth = 1000 Kbps
Requirements:
  35% FTP Traffic
  25% Telnet Traffic
  30% Voice Traffic (and with priority as I you let us see)
So,

Configurations:

  policy-map traffic
   class voice
    priority 300 (30% of 1000)
   class telnet
    bandwidth 250 (25% of 1000)
   class ftp
    bandwidth 350 (35% of 1000)

and I will use max-reseve-bandwidth 85 (15% of 700 = 100 Kbps aprox =
10% of 1000)

Ken.Farrington@barclayscapital.com ha escrito:
>
> I am really sorry to e-mail again on this topic, but my head is about
> to explode.
>
> (imagine its a 1Mbps cct)
> I have an excercise to do the folloiwng
>
> Users on a that share a serial line, should have the following
> restrictions
> :-
> 35% FTP Traffic
> 25% Telnet Traffic
> 30% Voice Traffic
>
> So, If I am asked a question such as the above,
>
> I should set the max-reseve-bandwidth to 90 on the interface, and
> configure the queing as such?
>
> policy-map traffic
> class voice
> priority 300
> class telnet
> bandwidth 25
> class ftp
> bandwidth 35
>
> now when I configure queueing and I have put the voice traffic into a
> strict LLQ, now my percentages change dont they?
>
> ie, we now have only 700k to play with for CBWFQ (imagine its a 1Mbps
> cct) and PLEASE NOTE, that i cant seem to find a "priority percent"
> command for LLQ - I assume one does not exist, so you have to specify
> LLQ in Kbits only.
>
> Is the 300k for voice correct, as I have calulated this as 30% of the
> total cct bandwidth, or should it be 30% of 900k as the
> max-reserved-bandwidth is set to 90.
>
> Also, I dont now know if I should adjust my telnet and FTP percentages

> to 25% of 700k or 25% of 600k as is the remaining bandwidth
> total-bandwidth minus LLQ reserved BW or 90% of the bandwdith minum
> LLQ reserved BW or will this just be done automatically? and I just
> leave these alone?
>
> I am just about to go jump in a lake :(
>
> Im sorry to persist with this, but I gues we must have a clear
> understanding of this for the lab.
>
> Many thx
>
> -----Original Message-----
> From: McCallum, Robert [mailto:robert.mccallum@thus.net]
> Sent: 22 October 2003 13:09
> To: 'Ken.Farrington@barclayscapital.com'; 'ccielab@groupstudy.com'
> Subject: RE: CBWFQ - Reseving BW for Voice
>
> Ken,
>
> The bandwidth command is the % bandwidth of the max bandwidth of the
> interface i.e. default 75% so when you specify 25% to go into a
> certain queue it is indeed 25% of 75% of interface bandwidth.
>
> Robert McCallum
> CCIE #8757 R&S
> 01415663448
> 07818002241
>
> > -----Original Message-----
> > From: Ken.Farrington@barclayscapital.com
> > [mailto:Ken.Farrington@barclayscapital.com]
> > Sent: 22 October 2003 12:24
> > To: ccielab@groupstudy.com
> > Subject: RE: CBWFQ - Reseving BW for Voice
> >
> >
> > fantasic. so if I were to get an excecise with the percentages
> > above the 75%, even thou the policy map will accpt the command, just

> > the fact that they have given me an excersise totals more than the
> > 75%, i must use the max-bandwidth command to 100, of what ever the
> > total in the excercise is? Personally, I would set to the percentage
> > maximum they have specified?
> >
> >
> > correct?
> >
> > thx soo much for you help !!!
> >
> >
> > -----Original Message-----
> > From: David Bartlett [mailto:David.Bartlett@reuters.com]
> > Sent: 22 October 2003 12:00
> > To: Ken.Farrington@barclayscapital.com; ccielab@groupstudy.com
> > Subject: RE: CBWFQ - Reseving BW for Voice
> >
> >
> > Ken
> >
> > Yes, you should use LLQ's priority queue for voice traffic to ensure

> > minimal delay variations. For this exercise you must set
> > max-reserved-bandwidth to 100% as you suggest as the default max is
> > 75%. If no class-default is configured, then traffic not matched by
> > your ACLs will not be dropped but will use the remaining 10% bw and
> > be given best effort treatment.
> >
> > Another important point to understand with LLQ is that using the
> > bandwidth statement specifies the *minimum* bw that the class can
> > use during periods of congestion. However, on the priority queue the

> > bandwidth specifies the *maximum* bw that the queue can use during
> > congestion periods. The priority queue is policied and traffic
> > exceeding the configured bw will be dropped.
> >
> > Hope this helps,
> >
> > David Bartlett
> >
> > -----Original Message-----
> > From: Ken.Farrington@barclayscapital.com
> > [mailto:Ken.Farrington@barclayscapital.com]
> > Sent: 22 October 2003 11:47
> > To: ccielab@groupstudy.com
> > Subject: CBWFQ - Reseving BW for Voice
> >
> >
> > All,
> >
> > Good Morning,
> >
> > Please can I confirm a couple of points.
> >
> > On the excersise below, Should I use for voice traffic, the
> > priority keyword as this I beleive invokes LLQ or should i just use
> > bandwidth (i think this may cause delay in the queing of voice data
> > and is not a good
> > idea?)
> >
> > What happens if I do not specify max-bandwidth on the interface to
> > 100 as my %s total 90% - Is this 90% of the 75% that is used by
> > default?
> >
> > If I dont specify a class-default, does all other traffic get
> > denied, or is just quese in the remain 25 percent reserved for other

> > traffic?
> >
> >
> > Please if someone could help me on these points, it would be
> > fantasic.
> >
> > Many thx,
> > Ken
> >
> >
> > I have an excercise to do the folloiwng
> >
> > Users on a that share a serial line, should have the following
> > restrictions
> > :-
> > 35% FTP Traffic
> > 25% Telnet Traffic
> > 30% Voice Traffic
> >
> > so, using CBWFQ config as below
> >
> > map-class voice
> > match access-group 100
> > map-class telnet
> > match access-group 110
> > map-class ftp
> > match access-group 120
> >
> > policy-map traffic
> > class voice
> > priority 30
> > class telnet
> > bandwidth 25
> > class ftp
> > bandwidth 35
> >
> >
> > acess-list ............
> >
> >
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-- 
Cristian E. Henry
REUNA

E-mail: chenry@reuna.cl
Fono: 56-2-3370336

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