From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Fri May 28 2004 - 12:39:49 GMT-3
The policer is only applied when the output queue is congested
however. Traffic matched by the LLQ can use bandwidth above it's
specified rate, however only traffic that conforms is guaranteed low
latency.
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: Kenneth Wygand [mailto:KWygand@customonline.com]
> Sent: Friday, May 28, 2004 6:48 AM
> To: Lord, Chris; Brian McGahan; ccielab@groupstudy.com
> Subject: RE: bandwidth-percent in class-default
>
> Chris,
>
> Yes, the "priority xxx" command used when configuring LLQ provides
that
> amount of bandwidth for a priority queue (always the first packet to
leave
> the CBWFQ) while also policing to that configured bandwidth. So it's
> multi-purpose.
>
> HTH,
> Ken
>
> -----Original Message-----
> From: Lord, Chris [mailto:chris.lord@lorien.co.uk]
> Sent: Fri 5/28/2004 6:29 AM
> To: Brian McGahan; Kenneth Wygand; ccielab@groupstudy.com
> Cc:
> Subject: RE: bandwidth-percent in class-default
>
>
>
> Thanks Brian, I see the point at long last. It got me thinking
> though, can you confirm my understanding that if a named class has an
LLQ
> then this does have an inbuilt policer. If for example you are using
an
> LLQ for voice, then presumably any excess voice traffic will be
dropped by
> the LLQ policer rather than joining the bun-fight for bandwidth in the
> class-default and potentially being subjected to different queueing
> policies (WFQ) which could cause jitter?
>
> Thx,
> Chris.
>
> -----Original Message-----
> From: Brian McGahan [mailto:bmcgahan@internetworkexpert.com]
> Sent: 27 May 2004 15:13
> To: Lord, Chris; Kenneth Wygand; ccielab@groupstudy.com
> Subject: RE: bandwidth-percent in class-default
>
>
> Chris,
>
> A bandwidth reservation in the MQC does not have a built
in
> policer. It is simply a minimum bandwidth reservation in the
case
> that
> the output queue is full. Traffic of the defined class can
still
> exceed
> the reserved value though. What you can run into with the first
> example
> is FTP saturating the line. As default traffic is not reserved,
it
> is
> possible that it may not get admission to the output queue.
>
>
> 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
> > Lord, Chris
> > Sent: Thursday, May 27, 2004 6:05 AM
> > To: Kenneth Wygand; Brian McGahan; ccielab@groupstudy.com
> > Subject: RE: bandwidth-percent in class-default
> >
> > I'm only a rookie but......
> >
> > Whilst Brian's comment are absolutely correct, in practice,
surely
> option
> > 1 & 2 give the same result given that there is only an FTP
class
> and a
> > class-default. Non-FTP traffic would only get less than 10% if
a
> third
> > class was to be introduced later.
> >
> > It's also my understanding that there are differences between
the
> version
> > of IOS you are using. I'm not sure when it changed (12.2 ish)
but
> in
> > earlier versions the bandwidth command "specified bandwidth
> allocation
> as
> > a percentage of the max-reserved-bandwidth". In later version
the
> > bandwidth command "specifies bandwidth as a percentage of the
> underlying
> > link rate". So....
> >
> > Older IOS & Option 1 gives
> >
> > FTP: 90% (BW) of 90% (MRB) = 81% of link speed
> > non-FTP (inc protocals and everything else) gets remaining 19%
of
> link
> > speed
> >
> > Older IOS & Option 2 gives
> >
> > FTP: 90% (BW) of 100% (MRB) = 90% of link speed
> > non-FTP (inc everything else) gets remaining 10% of link speed
> >
> > Newer IOS and Option 1 and 2 gives
> >
> > FTP: 90% (BW) of link speed
> > non-FTP (inc everything else) get remaining 10% of link speed
> >
> > On the newer IOS the max-reserved-bandwidth command only seems
to
> serve as
> > a warning marker during configuration rather than affecting
the
> maths.
> Or
> > am I completely off-course here?
> >
> > Regards,
> >
> > C.
> >
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: Kenneth Wygand [mailto:KWygand@customonline.com]
> > Sent: 27 May 2004 06:18
> > To: Brian McGahan; ccielab@groupstudy.com
> > Subject: RE: bandwidth-percent in class-default
> >
> >
> > Hey Brian,
> >
> > I see... FTP traffic can basically get more than 90% of
traffic
> with
> my
> > first configuration during congestion while other traffic
would be
> > guaranteed the other 10% of traffic during periods of
congestion.
> >
> > My real uncertainty lies in the "class-default". Does
> system-generated
> > traffic (routing processes, etc) fall into this class or would
> that
> > traffic potentially starve if all remaining bandwidth (to fill
up
> 100%)
> > was guaranteed in the class-default (of course this could only
be
> done
> by
> > changing the "max-reserve-bandwidth" value to 100%).
> >
> > TIA,
> > Ken
> >
> > -----Original Message-----
> > From: Brian McGahan
[mailto:bmcgahan@internetworkexpert.com]
> > Sent: Thu 5/27/2004 1:08 AM
> > To: Kenneth Wygand; ccielab@groupstudy.com
> > Cc:
> > Subject: RE: bandwidth-percent in class-default
> >
> >
> >
> > Ken,
> >
> > Yes there is a difference. In the first
> configuration
> non
> > FTP
> > traffic is not guaranteed bandwidth in the case of
> congestion.
> In
> > the
> > second configuration, non FTP traffic is guaranteed 10%
of
> the
> > output
> > queue in the case of congestion.
> >
> > 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
> > > Kenneth Wygand
> > > Sent: Wednesday, May 26, 2004 10:04 PM
> > > To: ccielab@groupstudy.com
> > > Subject: bandwidth-percent in class-default
> > >
> > > Is there a difference between the results of the
following
> > configurations?
> > >
> > > My requirement is to reserve 90% of the interface
> bandwidth
> for
> > FTP
> > and
> > > 10% for everything else. Note the explicit
> "bandwidth-percent"
> > > configuration command under the "class-default" my
policy-
> map.
> > >
> > > <snip>
> > > OPTION 1:
> > > class ftp
> > > match protocol ftp
> > > policy-map 90forFTP
> > > class ftp
> > > bandwidth-percent 90
> > > interface s0
> > > max-reserve-bandwidth 90
> > > service-policy 90forFTP
> > >
> > > OPTION 2:
> > > class ftp
> > > match protocol ftp
> > > policy-map 90forFTP
> > > class ftp
> > > bandwidth-percent 90
> > > class class-default
> > > bandwidth-percent 10
> > > interface s0
> > > max-reserve-bandwidth 100
> > > service-policy 90forFTP
> > > </snip>
> > >
> > > Thanks in advance,
> > > Ken
> > >
> > >
> >
>
This archive was generated by hypermail 2.1.4 : Wed Jun 02 2004 - 11:12:18 GMT-3