From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Sat Mar 13 2004 - 17:46:56 GMT-3
"bandwidth remaining percent" doesn't directly relate to the
max-reserved-bandwidth value. Take the following example:
Policy-map XYZ
Class A
Bandwidth percent 30
Class B
Bandwidth percent 20
Class C
Bandwidth percent 10
Classes A, B, and C have reserved 60% of the bandwidth in this
policy, and 40% is left unreserved for the default class. In the case that
the line is saturated, class A gets 30% of the output queue, class B gets
20%, and class C gets 10%, but what happens to the rest of the 40% that is
unreserved?
Keep in mind that the "bandwidth" statement is a *minimum* bandwidth
reservation. When there is no congestion, these classes can use as much
bandwidth is available. Now suppose that class A is using 30%, B 20%, and C
10%, and there is no default traffic being dequeued. The ratios of the
defined classes now gets transferred over into the default class as
"remaining" percentages. This means that classes A, B, and C share the
default class in the ratio of 3:2:1.
Now suppose that you want class C to get more of the default class
when there is saturation of everything except the default class. This is
the case where it is appropriate to configure the "bandwidth remaining
percent" such as follows:
Policy-map XYZ
Class A
Bandwidth percent 30
bandwidth remaining percent 25
Class B
Bandwidth percent 20
bandwidth remaining percent 25
Class C
Bandwidth percent 10
bandwidth remaining percent 50
Now in the case of complete saturation *and* the absence of any
default traffic, the following will occur:
Class A: 30% of interface bandwidth, 25% of class-default
Class B: 20% of interface bandwidth, 25% of class-default
Class C: 10% of interface bandwidth, 50% of class-default
Make sense?
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
Outside US: 775-826-4344 x 705
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> alsontra@hotmail.com
> Sent: Saturday, March 13, 2004 3:39 PM
> To: Tom Wojahn; William Chen
> Cc: ccielab@groupstudy.com
> Subject: Re: converting custom queue to cbwfq
>
> William,
> I understand and agree with Tom's calculations. Where does the
> "bandwidth remaining percent" command come into place? I know that the
> class-default takes its bandwidth from the reserved 25% of interface
> bandwidth, so are you saying that the "bandwidth remaining percent"
> command
> adjust the interfaces reserved bandwidth?
>
> Thanks,
> Alsontra
>
>
> ----- Original Message -----
> From: "William Chen" <kwchen@netvigator.com>
> To: "Tom Wojahn" <enthusiastictom@writeme.com>; "ccie r&r oup"
> <ccielab@groupstudy.com>
> Sent: Saturday, March 13, 2004 10:00 AM
> Subject: Re: converting custom queue to cbwfq
>
>
> > You can also use the "bandwidth remaining percent" command, that you can
> > reserve 25% of reserved bandwidth.
> >
> > William Chen
> >
> > ----- Original Message -----
> > From: "Tom Wojahn" <enthusiastictom@writeme.com>
> > To: "ccie r&r oup" <ccielab@groupstudy.com>
> > Sent: Saturday, March 13, 2004 11:16 PM
> > Subject: converting custom queue to cbwfq
> >
> >
> > > I have a scenario where you are given
> > > the reason I am asking is my answers did not match the answers given
> > >
> > > 128kb serial line
> > >
> > > A custom queue
> > >
> > > queue-list 1 protocol ip 1 tcp telnet
> > > queue-list 1 protocol ip 2 tcp 53
> > > queue-list 1 protocol ip 3 dlsw
> > > queue-list 1 protocol ip 4 tcp www
> > >
> > > queue list 1 queue 1 byte count 2000
> > > queue-list 2 queue 1 byte count 1000
> > > queue-list 3 queue 1 byte count 4000
> > > queue-list 4 queue 1 byte count 1000
> > >
> > > build a CBWFQ using percent not kb
> > >
> > > My theory and work
> > >
> > > In this case the bandwidth of 128 not valuable information
> > >
> > > I have a total of 8000 bytes on the custom queue
> > >
> > > policy-map converttocbwfq
> > > class-map telnet
> > > bandwidth percent 2000/8000 or 25% to get to 75% 25/100 =
> > > x/75 19%
> > > class map tcpdns
> > > bandwidth percent 1000/8000 or 12.5% to get to 75 %
> 12.5/100
> > > = x/75 9.375% 9%
> > > class map dlsw
> > > bandwidth percent 4000/8000 or 50 % to get to 75%
> > > 50/100=x/75 38%
> > >
> > > class map www
> > > bandwidth percent 1000/8000 pr 12.5 % to get to 75% 12.5
> > > /13=x/75 9.375 9%
> > >
> > >
> > > total percent 19+9+38+9 = 75%
> > >
> > >
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