From: Petr Lapukhov (petr@internetworkexpert.com)
Date: Wed Nov 29 2006 - 13:56:10 ART
This has been a long source of QoS controversy around :)
Actually, DocCD says it's WFQ. let's see if it's true:
-------------------
R1#show policy-map TEST
Policy Map TEST
Class class-default
!
interface FastEthernet0/0
service-policy output TEST
!
R1#show queueing interface fastEthernet 0/0
Interface FastEthernet0/0 queueing strategy: none
so it's FIFO when class-default is configured ALONE within policy-map.
--------------------
Let's add some other class:
R1#show policy-map TEST
Policy Map TEST
Class VOICE
Strict Priority
Bandwidth 10 (%)
Class class-default
R1#show queueing interface fastEthernet 0/0
Interface FastEthernet0/0 queueing strategy: fair
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 65000 kilobits/sec
It's WFQ now, what about the policy-map?
R1#show policy-map interface fastEthernet 0/0
FastEthernet0/0
Service-policy output: TEST
Class-map: VOICE (match-all)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: ip dscp ef
Queueing
Strict Priority
Output Queue: Conversation 264
Bandwidth 10 (%)
Bandwidth 10000 (kbps) Burst 250000 (Bytes)
(pkts matched/bytes matched) 0/0
(total drops/bytes drops) 0/0
Class-map: class-default (match-any)
156 packets, 18988 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: any
Note that Priority Queue has been allocated conversation number 264 but
there's
nothing said about class-default. Quite confusing!
However, we have to conclude, that conversations 1-256 are actually
allocated for
class-default (who else could claim them?), let's see if we can tune this:
policy-map TEST
class VOICE
priority percent 10
class class-default
fair-queue 512
R1#show queueing interface fastEthernet 0/0
Interface FastEthernet0/0 queueing strategy: fair
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/512 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 65000 kilobits/sec
Number of conversations is 512 now, and it's the same group of conversations
that was previously allocated for class-default (only the number was 256)
R1#show policy-map interface fastEthernet 0/0
FastEthernet0/0
Service-policy output: TEST
Class-map: VOICE (match-all)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: ip dscp ef
Queueing
Strict Priority
Output Queue: Conversation 520
Bandwidth 10 (%)
Bandwidth 10000 (kbps) Burst 250000 (Bytes)
(pkts matched/bytes matched) 0/0
(total drops/bytes drops) 0/0
Class-map: class-default (match-any)
208 packets, 25344 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: any
Queueing
Flow Based Fair Queueing
Maximum Number of Hashed Queues 512
(total queued/total drops/no-buffer drops) 0/0/0
This time policy-map reflect our changes...
Go figure the truth now :)
HTH
2006/11/29, Vincent Mashburn <vmashburn@fedex.com>:
>
> Actually, the class-default is fifo unless you explicitly configure
> fair-queue under the class-default in your policy map.
>
> Vince Mashburn
> Sr. Voice / Data Engineer
> 901-263-5072
> CCVP, CCNP
> Cisco IP Telephony Support Specialist
> Cisco IP Telephony Operations Specialist
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Petr Lapukhov
> Sent: Wednesday, November 29, 2006 1:37 AM
> To: Kal Han
> Cc: Groupstudy; Cisco certification
> Subject: Re: QoS questions.
>
> Please, see comments inline:
>
> 2006/11/29, Kal Han <calikali2006@gmail.com>:
> >
> > Hi
> >
> > Question 1
> > ---------------
> > When I am want to shape traffic on a frame-relay interface,
> > based on dlci - After create a policy-map and apply it on an
> > interfaces, should I also enable *"frame-relay traffic-shaping"*
> > or is this command only useful when I configure my policy
> > using *"map-class frame-relay"* and individually applying these
> > class per dlci
> > Sorry this could be a dumb question but I didnt understand.
>
>
> You only need to enable "frame-relay traffic-shaping" for legacy FRTS
> configuration, i.e. when you specify CIR/minCIR/Bc/Be whithin
> map-class with "frame-relay cir", "frame-relay mincir" etc command.
>
> MQC FRTS, and pure MQC configs do not require this command.
>
> Question 2 : class-default and fair-queue
> > ----------------------------------------------------------
> > For the class-default, I see there is an option to enable fair-queue.
> > Is it not the default ? if not what is the default ?
>
>
> By default "class-default" uses flow-based WFQ, as per the DocCD. You
> may
> not observe this with "show policy map", however "show queueing
> interface"
> gives a clue. By default, WFQ is able to accomodate for 256
> conversations.
>
> If you want to change the queue to FIFO, you need to specify the
> "bandwidth"
> keyword under class-default.
>
> <DocCD>
> By default, the class-default class is defined as flow-based WFQ.
> However,
> configuring the
> default class with the bandwidth policy-map class configuration command
> disqualifies
> the default class as flow-based WFQ.
> </DocCD>
>
> Question 3: LLQ Vs custom PQ
> > ----------------------------------------------
> > If LLQ itself is a priority queue, is the reason for using the
> priority
> > queuing,
> > because priority queuing offers more choices of prioritizing traffic ?
> >
> > and when I have a priority-list of a particular protocol with a
> > *low*priority,
> > example:
> >
> > access-list 10 permit 239.1.1.0 0.0.0.255
> >
> > priority-list 1 protocol ip *low *list 10
> >
> > does it mean the rest of the traffic (un-classified default)
> > is still* lower* priority than the ip traffic my acl selects ?
>
>
> The biggest difference between legacy PQ and LLQ is that PQ permits
> low-priority queues *starvation*. That is, with LLQ high priority queue
> is
> policed,
> and in contrary, with PQ all queues are served in order - from high to
> low,
> and
> until high has been emptied, no low queues are serverd.
>
> This is the main feature of PQ - it has 4 queues, served in strict
> order.
>
> HTH
>
> Thanks
> > Kal
> >
> >
> _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
>
>
>
> --
> Petr Lapukhov, CCIE #16379
> petr@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987
> Outside US: 775-826-4344
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
-- Petr Lapukhov, CCIE #16379 petr@internetworkexpert.comInternetwork Expert, Inc. http://www.InternetworkExpert.com Toll Free: 877-224-8987 Outside US: 775-826-4344
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