From: Carlos G Mendioroz (tron@huapi.ba.ar)
Date: Thu May 27 2004 - 08:34:44 GMT-3
Wow...
From:
http://www.cisco.com/en/US/tech/tk39/tk48/technologies_tech_note09186a00800fe2c1.shtml#understand
Cisco IOS Software Releases 12.1T and 12.2
In Cisco IOS Software Releases 12.1T and 12.2, the percentages that you
define in your classes are a percentage of the available bandwidth,
rather than the full interface or VC bandwidth.
Where the available bandwidth is calculated as follows:
Available Bandwidth = (max reserved bandwidth * interface bandwidth)
- (sum of priority classes)
Cisco IOS Software Releases 12.2T and 12.3
In Cisco IOS Software Releases 12.2T and 12.3, the bandwidth percent
command has been made consistent among 7500 and 7200 and below. This
means that now, the bandwidth percent is not referring anymore to a
percentage of the Available Bandwidth, but to a percentage of the
interface bandwidth. A class with a bandwidth percent command in a
policy-map now has a fix calculated amount of bandwidth allocated to it,
and the sum of all the bandwidth or bandwidth percent, priority and
priority percent classes together has to respect the max reserved
bandwidth rule.
The functionality of bandwidth percent as it was understood in Cisco IOS
Software Releases 12.1T and 12.2 for the Cisco 7200 and below platforms
has been preserved in Cisco IOS Software Releases 12.2T and 12.3 with
the introduction of the new command bandwidth remaining percent.
Lord, Chris wrote:
> 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
> >
> >
> _______________________________________________________________________
> > Please help support GroupStudy by purchasing your study materials
> from:
> > http://shop.groupstudy.com
> >
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Please help support GroupStudy by purchasing your study materials from:
> http://shop.groupstudy.com
>
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
>
> **********************************************************************
> The information contained in this email is confidential and is intended for the recipient only. If you have received it in error, please notify us immediately by reply email and then delete it from your system. Please do not copy it or use it for any purposes, or disclose its contents to any other person or store or copy this information in any medium. The views contained in this email are those of the author and not necessarily those of Lorien plc.
>
> Thank you for your co-operation.
> **********************************************************************
>
> _______________________________________________________________________
> Please help support GroupStudy by purchasing your study materials from:
> http://shop.groupstudy.com
>
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
-- Carlos G Mendioroz <tron@huapi.ba.ar> LW7 EQI Argentina
This archive was generated by hypermail 2.1.4 : Wed Jun 02 2004 - 11:12:17 GMT-3