From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Oct 22 2003 - 15:12:07 GMT-3
The 'definitive' answer for this thread is... it depends :)
Prior to certain 12.2 versions (not sure which exact release),
the 'bandwidth percent' and the 'priority percent' were relative
reservations based on what the available bandwidth of the interface was.
The 'available bandwidth' by default is 75% of the configured bandwidth,
minus any priority queues. To see what the available bandwidth is:
Rack1R1#sh queue e0/0
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 7500 kilobits/sec
As you can see from the above, the available bandwidth is
7500Kbps, which is 75% of the default interface bandwidth of 10Mbps.
This above router is running 12.2(15)T5, in which a reservation is
always ABSOLUTE. The following demonstrates so:
ip cef
!
class-map match-all FTP
match protocol ftp
!
policy-map QOS
class FTP
bandwidth percent 25
Rack1R1#sh queue e0/0 | in Available
Available Bandwidth 5000 kilobits/sec
Notice from the above output that the available bandwidth value
just decreased by 2.5Mbps, or 25% of 10Mbps. This is an ABSOLUTE
reservation. Now let's change the 'bandwidth percent 25' statement to
'bandwidth 2500':
policy-map QOS
class FTP
bandwidth 2500
Rack1R1#sh queue e0/0 | in Available
Available Bandwidth 5000 kilobits/sec
Notice the same output. This is still an ABSOLUTE reservation.
To understand how a RELATIVE bandwidth reservation works, see the
following thread:
http://www.groupstudy.com/archives/ccielab/200306/msg01688.html
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 708-362-1418 (Outside the US and Canada)
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> David Bartlett
> Sent: Wednesday, October 22, 2003 11:59 AM
> To: chenry@reuna.cl
> Cc: Ken.Farrington@barclayscapital.com; ccielab@groupstudy.com
> Subject: RE: CBWFQ - Reseving BW for Voice
>
> Cristian
>
> If you are using the ip rtp priority along with CBWFQ, then the
> max-reserved-bandwidth does exactly the same as for LLQ: it changes
the
> max bw that can be allocated across all classes + the rtp priority
queue
> from 75%.
>
> See:
>
>
http://www.cisco.com/en/US/products/sw/iosswrel/ps1830/products_feature_
> guide09186a0080087a94.html#15073
>
> David
>
> -----Original Message-----
> From: Cristian Henry H [mailto:chenry@reuna.cl]
> Sent: 22 October 2003 17:44
> To: David Bartlett
> Cc: Ken.Farrington@barclayscapital.com; ccielab@groupstudy.com
> Subject: Re: CBWFQ - Reseving BW for Voice
>
>
> I'm thinking in a scheme of PQ+WFQ, so for me the
max-reserved-bandwidth
> is applied only to the rest of bandwith without PQ, in that scene, the
> 85% is applied over 700 (1000-300), and that means 15% to the default
> traffic, that is, 100 Kbps aprox, that is 10% of total bandwidth as it
> was required.
>
> Any input about it?
>
> David Bartlett ha escrito:
> >
> > 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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