From: Chris Lewis \(chrlewis\) (chrlewis@cisco.com)
Date: Fri Jul 29 2005 - 14:51:48 GMT-3
I certainly wish to wind this up also, so I will not comment after this,
particularly as I don't think the subject is directly relevant to what
peope will or will not configure in the lab.
I guess we have to agree to disagree, but please consider what I am
saying and the implications of it being incorrect.
My position is that as a packet comes through a router, from a QoS
perspective it goes through classification, then policy is applied (as
per the policy-map, things like metering, marking, scheduling, dropping)
then shaping and finally on to the interface driver.
If shaping were applied prior to the policy-map actions, it would
nullify their effect, and make them ineffective.
Shaping takes a bursty input, queues things up and lets them out at a
nice steady rate that the interface can cope with. If shaping happened
before scheduling took place, there would be nothing for the scheduler
to do and no re-ordering would take place as the rate of traffic has
been shaped to the rate the interface can work with and no queues would
build up for the schedulers to work on.
I have confirmed these statements internally.
Chris
-----Original Message-----
From: Arun Arumuganainar [mailto:aarumuga@hotmail.com]
Sent: Friday, July 29, 2005 12:07 PM
To: Chris Lewis (chrlewis); A Molica; Bajo; gladston@br.ibm.com
Cc: ccielab@groupstudy.com; san
Subject: Re: Queue with GTS
FYI : Output Hold Queue is actually Software Queue . This is equal to
sum of the length of all software Queues. In a pure FIFO Hold Queue
length is actually Software Queue . What ever be the implementation if
Hold Queue limit is exceeded , it would be tail Drop for sure .
Note : Actually is Hardware Queue is actually called Transmit Ring .
Both hold queue and transmit ring are configurable .
Ok ... Lets us wind up gracefully . If you agree , We can certainly
agree to dis-agree !!!!
Thanks and Regards
Arun
----- Original Message -----
From: "Chris Lewis (chrlewis)" <chrlewis@cisco.com>
To: "Arun Arumuganainar" <aarumuga@hotmail.com>; "A Molica"
<ajmgrd-groupstudy@yahoo.com>; "Bajo" <bajoalex@gmail.com>;
<gladston@br.ibm.com>
Cc: <ccielab@groupstudy.com>; "san" <san.study@gmail.com>
Sent: Friday, July 29, 2005 7:22 PM
Subject: RE: Queue with GTS
> Arun,
>
> I think you are mis-interpreting that note, but then gain, we could
> just agree to disagree :)
>
> Here is how I read it.
>
> The points you list refer to the actions the interface driver take, as
> indicated by the following text that precedes the points you quote
> below
> :
>
> "The message is presented to the fast-send routine in the driver which
> does the following steps."
>
> The re-ordering that I'm referring to that are configured by priority
> or bandwidth statements happen before the packet gets to the interface
> driver. The way I look at it is ordering of packets for transmission
> is not dependant on the throughput rate of the egress interface. All
> the queuing policies that we configure with bandwidth and priority
> statements in a policy map do is get the right order of packets ready
> for transmission during times of congestion. Whether the interface can
> transmit at line rate or a lesser shaped rate is irrelevant to that
> action. The correct sequence of packets is processed by the queuing
> policy configured, then the interface driver decides how quickly to
> send that sequence of packets out, depending on interface speed and
> any shaping configured.
>
> One point that may also help is that the software queue in the
> document you refer to, is the output hold queue, that is not the queue
> where policy-map statements like priority and bandwidth take effect.
>
> Cheers
>
> Chris
>
> -----Original Message-----
> From: Arun Arumuganainar [mailto:aarumuga@hotmail.com]
> Sent: Friday, July 29, 2005 7:39 AM
> To: A Molica; Chris Lewis (chrlewis); Bajo; gladston@br.ibm.com
> Cc: ccielab@groupstudy.com; san
> Subject: Re: Queue with GTS
>
> Just check this out for More details . Quoting this for your info ...
>
> http://www.cisco.com/en/US/tech/tk364/technologies_tech_note09186a0080
> 09
> 3fdc
> shtml
>
> 1.. If traffic shaping is active, it compares the message arrival
> rate to the message transmission rate for the indicated class of
> messages. If either a shaping queue is forming on the subinterface or
> the queue is not present but the rate has now been exceeded, it places
> the message into a queue on the software interface.
> 2.. If traffic shaping is not active, does not apply to this
> message, or the rate has not been exceeded, the driver now asks
> whether the depth of the output controller's transmit queue is below
the tx-queue-limit.
> If it is below the limit, the driver simply queues the message for
> transmission. A message that followed this path is accounted as having
> been fast-switched on input and fast-switched on output.
> 3.. If it cannot be fast-switched, however, the driver diverts the
> message into a software queue, which is generically referred to as the
> "output hold queue". Examples of such hold queues include First In,
> First Out (FIFO) queuing, Priority Queuing, Custom Queuing, and
> Weighted Fair Queuing (WFQ).
>
> Thanks and Regards
>
> Arun
>
> ----- Original Message -----
> From: "A Molica" <ajmgrd-groupstudy@yahoo.com>
> To: "Chris Lewis (chrlewis)" <chrlewis@cisco.com>; "Arun
Arumuganainar"
> <aarumuga@hotmail.com>; "Bajo" <bajoalex@gmail.com>;
> <gladston@br.ibm.com>
> Cc: <ccielab@groupstudy.com>; "san" <san.study@gmail.com>
> Sent: Friday, July 29, 2005 5:51 PM
> Subject: RE: Queue with GTS
>
>
> > I would hope Chris is right, as voice and data packets could share
> > the
> same shaper, and I would want priority voice packets to get precedence
> over data packets when entering the shaper.
> >
> > "Chris Lewis (chrlewis)" <chrlewis@cisco.com> wrote:One small
> > correction
> here, packets go in to the software queue first,
> > then the shaper. The software queue is there to order packets based
> > off of priority or bandwidth configurations, then that order of
> > packets is fed in to the shaper, should packets need to be delayed
> > to keep to the shaped rate.
> >
> > Chris
> >
> > ________________________________
> >
> > From: Arun Arumuganainar [mailto:aarumuga@hotmail.com]
> > Sent: Thursday, July 28, 2005 1:04 AM
> > To: Bajo; gladston@br.ibm.com
> > Cc: ccielab@groupstudy.com; Chris Lewis (chrlewis); san
> > Subject: Re: Queue with GTS
> >
> >
> >
> >
> > ----- Original Message -----
> > From: gladston@br.ibm.com
> > To: Bajo
> > Cc: Arun Arumuganainar ;
> > ccielab@groupstudy.com ; Chris Lewis (chrlewis) ; san
> > Sent: Thursday, July 28, 2005 6:46 AM
> > Subject: Re: Queue with GTS
> >
> >
> >
> > Thanks,
> >
> > More clear now.
> >
> > This is from Wendell:
> >
> > "In some cases, IOS does not place the packets into a shaping queue
> > as they arrive, but instead the packets are placed into the Software
> > queue or TX Queue. When the shaping features knows that a
> newly
> > arrived packet does not exceed the shaping rate, there is no need to
> > delay the packet. In that case, a queuing tool used for managing the
> > shaping queue would also have no effect on that particular packet. "
> >
> >
> > [Arun]
> > This is absolutely true and this is how Shaping works . When a
> > packet arrives , it will check the token bucket if credit available
> > it will be sent to Software queue ( or directly to H/W queue if it
> > is not full ) . If credits are not available then this will be
> > placed in the shapping queue ( Read more about token bucket
algorithm for Details ).
> > [Arun]
> >
> > But, could you think about an example using a tool for queue created
> > by shaping and a tool queue for the main interface used at the same
> > time?
> > I remember that when we configure fragmentation, IOS creates two
> > queues on the main interface, and we can still use other tools (LLQ,
> CQ,
> > PQ, IP RTP Priority) on the queue created by shaping.
> >
> > Then, correcting my last post, this would occur:
> > |shaping queue|------->|software queue|-------->|hardware queue|
> >
> > LLQ Dual-Fifo
> > Fifo
> >
> > [Arun]
> >
> > See What queueing technique does shaping and software queues uses is
> > implementation specific .
> >
> > For Cisco with GTS the scenario look like this
> >
> > |shaping queue|------->|software queue|-------->|hardware queue|
> >
> > WFQ CQ or PQ or Fifo
> > Fifo
> >
> >
> >
> > For Cisco with FRTS th scenario look like this
> >
> > |shaping queue|------->|software queue|-------->|hardware queue|
> >
> > CQ or PQ or Fifo WFQ
> > Fifo
> >
> > Note :LLQ belong to different category . LLQ = Strict Priority Queue
> > + Policing . An Standalone LLQ can not be used for shapping ( A
> PQ
> > can be used instead of this ).
> >
> > Certainly you can verify this by configuring this in your lab
> >
> >
> > Hope it is clear now
> >
> > [Arun]
> >
> >
> > Any other example besides this one?
> >
> > Cordially,
> >
> > ------------------------------------------------------------------
> > Gladston
> >
> >
> >
> >
> > Bajo
> >
> > 27/07/2005 21:31
> > Please respond to
> > Bajo
> >
> >
> > To
> > Alaerte Gladston Vidali/Brazil/IBM@IBMBR cc san , Arun Arumuganainar
> > , ccielab@groupstudy.com, "Chris Lewis (chrlewis)"
> > Subject
> > Re: Queue with GTS
> >
> >
> >
> >
> >
> >
> > Hi all,
> >
> > Arun is correct. Take a look at the "Decision Logic for Queuing"
> > in
> > Wendell Odom's Cisco QoS, 2ed, page 358. Here are some points from
> > the book ...
> >
> > Shaping Queues exist separately from the interface software queues
> > ...
> >
> > After passing any Shaping tool (say PQ...etc), if there is any
> > shaping applied, packets are sent into Software Queues associated
> > with the physical interface and then forwarded out the interface.
> >
> > "If Hardware Queue is not full, packet are immediately placed in
> > Hardware Queue, bypassing the interface Software Queue....."
> >
> > On 7/27/05, gladston@br.ibm.com wrote:
> > > Hi San,
> > >
> > > I hope Arun answers it.
> > > As I see the process, there is a hardware queue and software
> > queue. I
> > > don't think it would exist something like this going on:
> > > |shaping queue|----->|sofware queue|---->|hardware queue|
> > >
> > > The shaping queue is itself a software queue.
> > > Would IOS move from a software queue (called shaping queue) to
> > another
> > > software queue(called just "software queue")?
> > >
> > > Cordially,
> > >
> > ------------------------------------------------------------------
> > > Gladston
> > >
> > >
> > >
> > >
> > > san
> > > 27/07/2005 12:29
> > > Please respond to
> > > san
> > >
> > >
> > > To
> > > Arun Arumuganainar
> > > cc
> > > Alaerte Gladston Vidali/Brazil/IBM@IBMBR, "Chris Lewis
> > (chrlewis)"
> > > , ccielab@groupstudy.com
> > > Subject
> > > Re: Queue with GTS
> > >
> > >
> > >
> > >
> > >
> > >
> > > Hi Arun,
> > >
> > > Can you give an example of how to modify a software queue ?
> > Is it by
> > > the command "fair-queue , no fair-queue" under the interface.
> > I know
> > > shaping queue can be modified with shapping configurations
> > > (FRTS/GTS/CBTS).
> > >
> > > Dumb Question, If i use shaping, does the software queue is
> > > overwritten by shapping queue or still packet goes through
> > both the
> > > queues like below
> > > PQ with GTS :
> > > interface serial 0
> > > priority-group 4 ((priority queue to define software queue))
> > > traffic-shape rate xxxx (( to create a shapping queue ))
> > >
> > >
> > > /SAN
> > >
> > > On 7/27/05, Arun Arumuganainar wrote:
> > > > Actually there are 3 queues in IOS .
> > > >
> > > > 1) Hardware Queue :- Single Queue and Always FIFO . We can
> > not do any
> > > thing
> > > > about it
> > > > 2) Software Queue
> > > > 3) Shaping Queue ( Will be used only when shaping is turned
> > on ) .
> > > >
> > > > How Packets are enqued in Software or Shaping Queue ?
> > > >
> > > > Well the answer lies in what kind of traffic shaping you you
> > use . Here
> > > are
> > > > the details .
> > > >
> > > > 1) GTS : Shaping Queue : WFQ only supported . Software
> > Queue : PQ ,
> > > CQ or
> > > > FIFO
> > > > 2) FRTS : Shaping Queue : PQ, CQ and FIFO Software Queue :
> > WFQ only
> > > > 3) CB-Traffic Shaping : Uses WFQ for both Shaping and
> > Software Queue .
> > > >
> > > > Well the " sh interface " o/p tells you only about the
> > software queue
> > > and
> > > > "show traffic " will give you about shaping queue .
> > > >
> > > > Hope this helps .
> > > >
> > > > Thanks and Regards
> > > > Arun
> > > > ----- Original Message -----
> > > > From:
> > > > To: "Chris Lewis (chrlewis)"
> > > > Cc:
> > > > Sent: Wednesday, July 27, 2005 12:37 AM
> > > > Subject: RE: Queue with GTS
> > > >
> > > >
> > > > > No, Chris, thanks a lot.
> > > > >
> > > > > That is what I was looking for.
> > > > >
> > > > > Wendell book confirmed that GTS uses WFQ.
> > > > >
> > > > > I read that before, but nothing like practice to memorize.
> > > > >
> > > > > Cordially,
> > > > >
> > ------------------------------------------------------------------
> > > > > Gladston
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > "Chris Lewis \(chrlewis\)"
> > > > > 26/07/2005 15:52
> > > > >
> > > > > To
> > > > > Alaerte Gladston Vidali/Brazil/IBM@IBMBR,
> >
> > > > > cc
> > > > >
> > > > > Subject
> > > > > RE: Queue with GTS
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Hi Gladston,
> > > > >
> > > > > This is how I would read the output.
> > > > >
> > > > > GTS acts upon an interface or subinterface. GTS here is
> > configured for
> > > a
> > > > > specific sub-interface and the queue that GTS will build
> > to do shaping
> > > > > on will use WFQ. The main interface can have fifo or wfq
> > configured on
> > > > > it. Are you looking at something else?
> > > > >
> > > > > Chris
> > > > >
> > > > > -----Original Message-----
> > > > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]
> > On Behalf
> > > Of
> > > > > gladston@br.ibm.com
> > > > > Sent: Tuesday, July 26, 2005 12:20 PM
> > > > > To: ccielab@groupstudy.com
> > > > > Subject: Queue with GTS
> > > > >
> > > > > Hi,
> > > > >
> > > > > GTS is applyed to interface serial 0/0.14.
> > > > > 'sh traffic queue' shows that the queue created by GTS
> > uses WFQ.
> > > > >
> > > > > It seems it does not matter what is configured on the
> > interface, in
> > > this
> > > > > case fifo.
> > > > >
> > > > > Would you comment this?
> > > > >
> > > > > Rack2R1(config-subif)#do sh traf que Traffic queued in shaping
> > > > > queue on Serial0/0.14 Queueing strategy: weighted fair
> > > > > Queueing Stats: 9/1000/64/10026 (size/max
> > total/threshold/drops)
> > > > > Conversations 2/4/16 (active/max active/max total) Reserved
> > > > > Conversations 0/0 (allocated/max allocated) Available
> > > > > Bandwidth 96 kilobits/sec
> > > > >
> > > > > (depth/weight/total drops/no-buffer drops/interleaves)
> > 5/32384/380/0/0
> > > > > Conversation 0, linktype: ip, length: 64
> > > > > source: 150.100.1.254, destination: 148.5.4.1, id: 0x03F6,
> > ttl: 254,
> > > > > TOS: 0 prot: 17, source port 55172, destination port 5002
> > > > >
> > > > > (depth/weight/total drops/no-buffer drops/interleaves)
> > 5/32384/766/0/0
> > > > > Conversation 7, linktype: ip, length: 64
> > > > > source: 150.100.1.254, destination: 148.5.4.1, id: 0x0020,
> > ttl: 254,
> > > > > TOS: 0 prot: 17, source port 51068, destination port 5001
> > > > >
> > > > >
> > > > > Rack2R1(config-subif)#do sh int ser 0/0 Serial0/0 is up, line
> > > > > protocol is up Hardware is PowerQUICC Serial MTU 1500 bytes,
> > > > > BW 64 Kbit, DLY 20000 usec, reliability 255/255, txload
> > > > > 255/255, rxload 10/255 Encapsulation FRAME-RELAY, loopback not
> > > > > set Keepalive set (10 sec) LMI enq sent 95, LMI stat recvd 95,
> > > > > LMI upd recvd 0, DTE
> > LMI up
> > > > > LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0 LMI DLCI 1023
> > > > > LMI type is CISCO frame relay DTE FR SVC disabled, LAPF state
> > > > > down Broadcast queue 0/64, broadcasts sent/dropped 178/0,
> > interface
> > > > > broadcasts 162
> > > > > Last input 00:00:01, output 00:00:00, output hang never Last
> > > > > clearing of "show interface" counters 00:15:49 Input queue:
> > > > > 0/75/0/0 (size/max/drops/flushes); Total
> > output drops:
> > > > > 10878
> > > > > Queueing strategy: fifo
> > > > > Output queue: 0/40 (size/max)
> > > > > 1 minute input rate 95000 bits/sec, 183 packets/sec
> > > > > 1 minute output rate 95000 bits/sec, 185 packets/sec
> > > > > 159447 packets input, 10401005 bytes, 0 no buffer Received 0
> > > > > broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0
> > > > > CRC, 0 frame, 0 overrun, 0 ignored, 0
> > abort
> > > > > 163288 packets output, 10609440 bytes, 0 underruns 0 output
> > > > > errors, 0 collisions, 0 interface resets 0 output buffer
> > > > > failures, 0 output buffers swapped out 0 carrier transitions
> > > > > DCD=up DSR=up DTR=up RTS=up CTS=up
> > > > >
> > > > >
> > > > > This is the config:
> > > > >
> > > > > interface Serial0/0.14 point-to-point bandwidth 128 ip address
> > > > > 148.5.14.1 255.255.255.0 traffic-shape rate 96000 12000 1000
> > > > > 1000 frame-relay
> > interface-dlci
> > > > > 104
> > > > >
> > > > >
> > >
> >
> ______________________________________________________________________
> _
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> > > > >
> > > > >
> > >
> >
> ______________________________________________________________________
> _
> > > > > Subscription information may be found at:
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> > > >
> > > >
> >
> ______________________________________________________________________
> _
> > > > Subscription information may be found at:
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> > >
> > >
> >
> ______________________________________________________________________
> _
> > > Subscription information may be found at:
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> > >
> >
> >
> > --
> > Kind Regards,
> >
> > Bajo
> >
> >
> ______________________________________________________________________
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> >
> >
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