QOS on WAN Edge

[Ibrahim Jamil]

Hi Experts

is it a good config the below for QOS on WAN edge to maintain the voice traffic and data ,when the congestion happend?pls ur comments

class-map match-any DATA

match ip dscp af21

class-map match-any CRITICAL-DATA

match  dscp cs3  af31

class-map match-any VOICE

match  dscp ef

class-map match-any SIGNALING

match dscp CS5

class-map match-any SCAVENGER

match ip dscp cs1  af11

policy-map WAN

class VOICE

  priority percent 15

class SIGNALING

bandwidth percent 5

class CRITICAL-DATA

  bandwidth percent 15

  random-detect dscp-based

class DATA

  bandwidth percent 25

  random-detect dscp-based

class SCAVENGER

  bandwidth percent 5

class class-default

  bandwidth percent 10

  random-detect

INT G0/3 

desc 8 E1 to Southen area

bandwith 20000

service-policy output WAN

thanks

jamil

[smehrnia]

Hi Ibrahim,

generally, it looks ok, you have to run it n see if it needs to be further adjusted.

but since u just pre-assigned 75% of ur link's BW, you have 25% unassigned there, you could use bandwidth remaining command to define IF there is any bandwidth left, how should it be devided between classes. it is totally optional n up to u though

Hope it Helps,

Soroush.

[Ibrahim Jamil]

Hi Soroush.

thanks for ur reply

in which class should i configure the bandwidth remaining?

[smehrnia]

when there is left over bandwidth, by default it will be devided between classes in a proportional manner. now if u want to override this default behaviour and assign more unused bandwidth to a certain class in case of congestion, you should config that command, it is totally up to you and the traffic vol. of each class.

here is a useful link for u:

http://www.cisco.com/en/US/tech/tk543/tk757/technologies_tech_note09186a0080103eae.shtml#howisunusedbandwidthallocated

plz Rate helpful posts.

HTH

Soroush.

[Ibrahim Jamil]

Thank a lot of ur reply

can i have the two service policy (1) inbound and (1)outbound at the same WAN interface?if so what is the difference

thanks

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Can't really say without knowing your network application service requirements.  What you have might work fine, make no difference or make things worse.

Generally, I recommend against using WRED, as its defaults often need tuning and on low bandwidth pipes, such as your E1, there's often few concurrent flows for it to work (well) against.

Also generally, I recommend avoiding, if possible, using FIFO queuing for multiple flows.

A generic good CBWFQ policy to start with, is:

policy-map WAN

class VOICE

priority percent 33

class class-default

fair-queue

If you really have needs to priorize/depriorize other traffic, and your router supports HQF, then something like:

policy-map WAN

class VOICE

priority percent 33

class PREFERENCE

bandwidth remaining percent 81

fair-queue

class SCAVENGER

bandwidth remaining percent 1

fair-queue

class class-default

bandwidth remaining percent 9

fair-queue

[Ibrahim Jamil]

Hi Joseph

thanks for ur reply

can u post me a full config according my input , also pls note i have 8 E1 connected to gig interface

thanks

jamil

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

Again, can't be specific without knowing much more about your service requirements.

However, using a gig interface with 8xE1 downstream, you should shape for that.

So something like. . .

INT G0/3 

desc 8 E1 to Southen area

bandwith 16000

service-policy output WAN_Shape_16Mb

policy-map WAN_Shape_16Mb

class class-default

shape average 16000000

service-policy WAN

When doing VoIP, your Tc should be about 10 ms or less, if not adjust your Bc.

I might be mistaken, but I suspect many shapers don't account for L2 overhead, if not shape 5 to 15% slower.

Oh, and class-maps could be like:

class-map match-any PREFERENCE

match ip precedence 7 6 5

match ip precedence 4 3 2

class-map match-any VOICE

match  dscp ef

class-map match-any SCAVENGER

match ip precedence 1

[Ibrahim Jamil]

Hi Joseph

Kindly, can y explain the below:

class-map match-any PREFERENCE

match ip precedence 7 6 5

match ip precedence 4 3 2

why in the class default y shaped to 8E1s then y have applied policy-map WAN?

class class-default

shape average 16000000

service-policy WAN

pls can y post me the full recomended config includes the classes-map and policy map in order to past it in my router

thanks

Jamil

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Kindly, can y explain the below:
class-map match-any PREFERENCE
match ip precedence 7 6 5
match ip precedence 4 3 2

This class catches all the traffic, that's not caught in other classes, that's to be treated better than best effort, i.e. given a preference over best effort and scavenger traffic.

why in the class default y shaped to 8E1s then y have applied policy-map WAN?
class class-default
shape average 16000000
service-policy WAN

Because if you have a gig interface and 8E1 downstream, QoS on just gig interface would only engage when there's congestion at gig interace.  This allows us to treat for congestion at the 8E1 bottleneck without having a QoS policy there.

pls can y post me the full recomended config includes the classes-map and policy map in order to past it in my router

I cannnot as I have insuffient information.  First, as I've mentioned twice, don't know your service requirements.  Second, don't know the platform nor it's installed IOS.

[Ibrahim Jamil]

Hi Joseph

thanks for ur reply

class-map match-any PREFERENCE

match ip precedence 7 6 5

match ip precedence 4 3 2

1)why ip precedence not DSCP in the above?

2)why in the below bandwidth remain percent not the bandwidth percent of the interface?

class PREFERENCE

bandwidth remaining percent 81

fair-queue

class SCAVENGER

bandwidth remaining percent 1

fair-queue

class class-default

bandwidth remaining percent 9

fair-queue

in the class default i have tried bandwidth percent X with fair queue but the IOS Refused the command until i get rid of the fair-queue,why those don't work together?

thanks

jamil

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

class-map match-any PREFERENCE
match ip precedence 7 6 5
match ip precedence 4 3 2
1)why ip precedence not DSCP in the above?

Just a "quicker" way to test  ToS bits, as IP Precedence only looks as first 3 bits, so for example, IP Precedence 3 would match CS3, AF31, AF32 and AF33 (it will also match the 4 private DSCP values too).  If you have a need to treat different DSCP values different, they match against the DSCP values.

2)why in the below bandwidth remain percent not the bandwidth percent of the interface?
class PREFERENCE
bandwidth remaining percent 81
fair-queue
class SCAVENGER
bandwidth remaining percent 1
fair-queue
class class-default
bandwidth remaining percent 9
fair-queue
in the class default i have tried bandwidth percent X with fair queue but the IOS Refused the command until i get rid of the fair-queue,why those don't work together?

I used remaining percent as it makes setting ratios easier for non-LLQ classes.

FQ and bandwidth remaining - maybe pre-HQF QoS. (An example of why it's difficult to provide correct syntax without knowing more information.)

[Ibrahim Jamil]

Thanks for ur reply

pls can y help in the below theread

https://supportforums.cisco.com/message/3695451#3695451

thanks

jamil