From: Godswill Oletu (oletu@inbox.lv)
Date: Sat Jul 15 2006 - 22:57:57 ART
Victor,
The original solution provided by Jeff looks correct, though I think a
little adjustment need to be done to the shaping aspect of the solution to
meet the requirement of the question that states:
>Limit all traffic leaving FA 0/0 (VlanX) with Precedence 2 to 128k.
> DO NOT use policing or rate-limiting and DO NOT use an ACL to match IP
> Precedence.
Though the shaper is not a good limiting mechanism, the above Task did not
leave us with much of an option, so one have to tweak the shaper so that, it
can at least have some feel of a limiter. However, the solution provider by
Jeff below did not meet the limiting aspect of the question.
>class-map match-any PREC_3_AND_OR_BB1
> match precedence 3
> match access-group 101
> class-map match-all PREC_2
> match precedence 2
> !
> policy-map VLANX_OUT
> class PREC_3_AND_OR_BB1
> bandwidth 128
> random-detect
> class PREC_2
> shape average 128000
> !
> interface FastEthernet0/0
> service-policy output VLANX_OUT
> !
> access-list 101 permit ip 1.1.20.0 0.0.0.255 150.100.1.0 0.0.0.255
In order to make sure the shaping mechanism limits the traffic to 128K.
> class PREC_2
> shape average 128000
The above statement have to be modified so that Be=0.
>shape average 128000
Have the potential to burst above 128K, so setting Be=0 will ensure that we
do not go above 128K.
When I labbed it, I am getting...
Rack1R3#sh policy-map interface fa0/0
FastEthernet0/0
Service-policy output: VLANX_OUT
Class-map: PREC_3_AND_OR_BB1 (match-any)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: precedence 3
0 packets, 0 bytes
5 minute rate 0 bps
Match: access-group 101
0 packets, 0 bytes
5 minute rate 0 bps
Queueing
Output Queue: Conversation 265
Bandwidth 128 (kbps)
(pkts matched/bytes matched) 0/0
(depth/total drops/no-buffer drops) 0/0/0
exponential weight: 9
mean queue depth: 0
class Transmitted Random drop Tail drop Minimum Maximum
Mark
pkts/bytes pkts/bytes pkts/bytes thresh thresh
prob
0 0/0 0/0 0/0 20 40
1/10
1 0/0 0/0 0/0 22 40
1/10
2 0/0 0/0 0/0 24 40
1/10
3 0/0 0/0 0/0 26 40
1/10
4 0/0 0/0 0/0 28 40
1/10
5 0/0 0/0 0/0 30 40
1/10
6 0/0 0/0 0/0 32 40
1/10
7 0/0 0/0 0/0 34 40
1/10
rsvp 0/0 0/0 0/0 36 40
1/10
Class-map: PREC_2 (match-all)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: precedence 2
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
128000/128000 1984 7936 7936 62 992
Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
- 0 0 0 0 0 no
Class-map: class-default (match-any)
1 packets, 60 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: any
Rack1R3#
You can see that Class 'PREC_2' has Be=7936, it should be set to zero to be
able to limit the traffic to 128K.
HTH
Godswill Oletu
CCIE #16464
----- Original Message -----
From: "Victor Cappuccio" <cvictor@protokolgroup.com>
To: "'Godswill Oletu'" <oletu@inbox.lv>
Cc: <ccielab@groupstudy.com>
Sent: Saturday, July 15, 2006 8:45 PM
Subject: RE: congestion avoidance question
Hi Godswill so the configuration should look
> > policy-map VLANX_OUT
> > class PREC_3_AND_OR_BB1
> > bandwidth 128
> > random-detect
> > class PREC_2
> > bandwidth 128
> > random-detect
?
-----Mensaje original-----
De: Godswill Oletu [mailto:oletu@inbox.lv]
Enviado el: Sabado, 15 de Julio de 2006 08:15 p.m.
Para: Kay D; Michael Stout
CC: cvictor@protokolgroup.com; jeffryanwn@hotmail.com;
ccielab@groupstudy.com
Asunto: Re: congestion avoidance question
Guarantee does not necessary call for the use of priority queue. The use of
bandwidth is enough to guarantee your traffic in the event of a congestion.
Also the mention of 'minimum' as stated in the original question, will not
make priority queue look good as an option.
> vlan has a guaranteed minimum bandwidth of 128k
Priority queue have an inbuilt policer and it set a maximum and not a
minimum transmission rate. Once that maximum is reached other traffic will
be queued as best effort ie 'no guarantee' and since there is already a
congestion on the interface to begin with, anything above 128K will not be
transmitted, this will run contrary to the objective of the question which
establish a minimum transmission of 128K but leaves the maximum bound open.
IMHO, Bandwidth with randon detect should be enough to meet the objective of
the question.
Godswill Oletu
CCIE #16464
----- Original Message -----
From: "Kay D" <krsna83@gmail.com>
To: "Michael Stout" <michaelgstout@hotmail.com>
Cc: <cvictor@protokolgroup.com>; <jeffryanwn@hotmail.com>;
<ccielab@groupstudy.com>
Sent: Saturday, July 15, 2006 5:31 PM
Subject: Re: congestion avoidance question
> Hi,
> The word "guaranteed" makes us think that we would have to use
> "priority queue"
> but the keyword "in case of congestion drop them randomly" makes me
> think that
> there is no difference between "priority queue" and " bandwidth "
> ,,,,as anyways packets would be dropped if there is congestion .
>
> The second part of matching the packets with prec value of 2 and
> assigning a bandwidth , should work with "bandwidth 128" .
>
> Please correct me if i am wrong .
>
> TIA
> Kay D
> Michael Stout wrote:
> > i agree.
> >
> > i think the guaranteed minimum bandwidth of 128k makes a priority queue
a
> > requirement.
> >
> > --------------------------------------------------------------------
> >
> > From: "Victor Cappuccio" <cvictor@protokolgroup.com>
> > Reply-To: "Victor Cappuccio" <cvictor@protokolgroup.com>
> > To: "'Jeff Ryan'" <jeffryanwn@hotmail.com>, "'Cisco certification'"
> > <ccielab@groupstudy.com>
> > Subject: RE: congestion avoidance question
> > Date: Sat, 15 Jul 2006 17:01:35 -0400
> > Hi there Jeff,
> >
> > I think that
> > class PREC_2 is using the priority 128 command.
> >
> > BTW I would like to know which workbook you are using, because I'm
> > looking
> > for a Workbook Specific to QOS Thanks
> > Vmctor.-
> >
> > -----Mensaje original-----
> > De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de
> > Jeff
> > Ryan
> > Enviado el: Sabado, 15 de Julio de 2006 04:41 p.m.
> > Para: Cisco certification
> > Asunto: congestion avoidance question
> >
> > All, I'm doing a lab and it is aking me to make sure that all traffic
> > leaving
> > FA 0/0 (VlanX) set with Precedence 3 AND/OR traffic from VlanX
> > destined to
> > BB1
> > vlan has a guaranteed minimum bandwidth of 128k. Also, make sure that
> > in
> > case
> > of congestion that these packets get dropped randomly.
> >
> > Limit all traffic leaving FA 0/0 (VlanX) with Precedence 2 to 128k.
> > DO NOT
> > use
> > policing or rate-limiting and DO NOT use an ACL to match IP
> > Precedence.
> >
> > Does this look correct? Thanks in advance - Jeff
> >
> > --------
> > R2#
> > !
> > ip cef
> > !
> > class-map match-any PREC_3_AND_OR_BB1
> > match precedence 3
> > match access-group 101
> > class-map match-all PREC_2
> > match precedence 2
> > !
> > !
> > policy-map VLANX_OUT
> > class PREC_3_AND_OR_BB1
> > bandwidth 128
> > random-detect
> > class PREC_2
> > shape average 128000
> > !
> > interface FastEthernet0/0
> > service-policy output VLANX_OUT
> > !
> > access-list 101 permit ip 1.1.20.0 0.0.0.255 150.100.1.0 0.0.0.255
> > !
> >
> >
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