From: Pierre-Alex (paguanel@hotmail.com)
Date: Sun Jun 04 2006 - 09:16:18 ART
No worry.
You have helped me quite a bit already.
I am familiar with the link:
http://www.cisco.com/en/US/tech/tk543/tk544/technologies_tech_note09186a00800
94612.shtml
the other is for ATM, so I am not sure if it is releavant.
I have done plenty of reading on Qos but not enough hands-on to see it at
work.
I will do that and see if everything falls better into place.
Thanks again.
Pierre
----- Original Message -----
From: Petr Lapukhov
To: Pierre-Alex
Cc: ccielab@groupstudy.com
Sent: Sunday, June 04, 2006 2:05 PM
Subject: Re: QoS default-class - oversubscription
Pierre,
unfortunately, I have not much time to write thorough explanation,
but I do recommend you to look at the following links:
http://www.cisco.com/en/US/tech/tk39/tk824/technologies_tech_note09186a0080
0c9699.shtml
http://www.cisco.com/en/US/tech/tk39/tk824/technologies_tech_note09186a0080
093d62.shtml#
http://www.cisco.com/en/US/tech/tk543/tk544/technologies_tech_note09186a008
0094612.shtml
They may give you some good insight on how CBWFQ actually works, and how
that
"ureservable" bandwidth is used. Just remember the key idea - "bandiwidth"
is just
a weighting factor for undelying WFQ algorithm.
HTH
Petr
2006/6/4, Pierre-Alex <paguanel@hotmail.com>:
I have labed point number 2 and I my statement is actually wrong!
With the configuration as is, the router will refuse the commands because
the
available bandwidth is actually 75% of the interface bandwidth .
( I think I got confused because when I did the test with shapping, I was
abled to use 100% of the shapped rate. )
----- Original Message -----
From: Pierre-Alex
To: ccielab@groupstudy.com
Sent: Sunday, June 04, 2006 11:38 AM
Subject: QoS default-class - oversubscription
I need a quick "yes" or "no" + quick optional comments on the following
points .
Theses are deductions I have made from several readings on CCO and
research
in the group-study archives.
I just want to make sure I am not inventing wrong rules here ...
1. QoS bandwidth usage is calculated based on L3 packet size.
2. On non-7500 + platforms: 25% of the interface bandwidth SHOULD be
left
aside for overhead traffic, including Layer 2 (frame? overhead), control
traffic (routing,cdp,snmp etc ...), and best-effort traffic. This traffic,
and
in particular NON IP traffic, will be allocated to the DEFAULT-CLASS
Because the 25% is a recommendation and is NOT enforced by the routers
when
using absolute bandwidth values. Nothing prevents me from doing the
following
and starve my overhead traffic.
interface s 0/0
bandwidth 100
policy a
class 1
bandwidh 90
class 2
banwith 10
clas-class default
3. The command "maximum bandwith-percent xx" is only releavant when
using
configurations with "bandwidth percent" .
When left to the default maximum bandwith-percent 75 of interface
bandwidth
and when using "bandwidth percent " type configurations, then the overhead
is
taken care off.
When changed to maximum bandwith-percent 100 then care must be taken to
leave enough in the default class for overhead traffic.
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