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Joe Lee
Beginner

QoS Shaping Issue

Hi,

I am working on creat the QoS Policy with the shaping. Please the policy below.

class-map match-any mail

match protocol exchange

match protocol smtp

!

class-map match-any system

match protocol ftp

match protocol telnet

!

class-map match-any high

match access-group 2222

!

class-map match-any low

match protocol http url "xxx.com*"

match class-map mail

match class-map system

!

policy-map low_family

class mail

bandwidth percent 80

class system

bandwidth percent 20

!

policy-map ABC

class high

shape average percent 60

class low

shape average percent 40

service-policy low_family

In the red hightlight,

Can I do like this without matching two class-map since they will fall into the low class policy?

class-map match-any low

match protocol http url "xxx.com*"

Please advise. Thanks.

5 REPLIES 5
stevjarbeck
Beginner

Yes.

Steve

Hi Steve,

Can you please provide me little details? or link will be helpful.

Thanks.

Sorry for giving you the wrong answer.  I've had the flu for the past week and obviously my brain isn't functioning yet.

OK.

You want to take this:

class-map match-any low

match protocol http url "xxx.com*"

match class-map mail

match class-map system

and break it down to this:

class-map match-any low

match protocol http url "xxx.com*"

Here is the issue:

policy-map low_family

class mail

bandwidth percent 80

class system

bandwidth percent 20

!

policy-map ABC

class high

shape average percent 60

class low

shape average percent 40

service-policy low_family

In your policy map, as it classifies traffic it will reach "low".  The classification for low contains mail, system and the URL.  If you remove mail and system from the classification when it reaches your policy classifcation of low it will only classify the URL and apply the policy of low_family. Even though low_family matches mail and system, the policy-map itself that you attach to the interface won't match mail and system.

Let me try to break it down a bit easier.

Traffic goes out and the router classifies the traffic.  It sees high which is ACL based and gives this priority.  It won't see mail and system if you remove that from class-map match-any low even though you have it in the policy-map.  It will only know when to apply the policy-map when the classification critera has been met.  Without this, it won't know what to do with mail and system.   You can provide more control over the remaining 40% by applying another policy-map to it, as you did.

I would re-work it this way:

class-map match-any LowURL

match protocol http   url "*youtube*"

policy-map low_family

class mail

bandwidth percent 70

class system

bandwidth percent 20

class LowURL

bandwidth percent 10

OR

class class-default
  fair-queue

Does that help?

Again, sorry for confusing you earlier.

References:

http://www.cisco.com/en/US/docs/ios/12_2/qos/configuration/guide/fqos_c.html

http://www.cisco.com/en/US/docs/ios/12_2/qos/configuration/guide/qcfcbshp.html#wp1002748  <--I recommend looking at this.

http://www.cisco.com/en/US/docs/ios/12_0t/12_0t5/feature/guide/cbwfq.html (Class-Based Weighted Fair Queueing)

Hi Steve,

Thank you so much for your help. I have two more questions...

1. Based on the policy below,

class-map match-any low

match protocol http url "youtub.com*"

match class-map mail

match class-map system

!

policy-map low_family

class mail

bandwidth percent 80

class system

bandwidth percent 20

!

policy-map ABC

class high

shape average percent 60

class low

shape average percent 40

service-policy low_family

If the url"youtube.com*" is place in a low (parent) policy, but not within the low family policy, how is that traffic handled in relation to CBWFQ defined in the low family policy?

2. What takes precedence for classification of traffic, NBAR or access-list?

Regards,

Joe

If the url"youtube.com*" is place in a low (parent) policy, but not within the low family policy, how is that traffic handled in relation to CBWFQ defined in the low family policy?

"If a default class is configured with the bandwidth policy-map class configuration command, all unclassified traffic is put into a single queue and given treatment according to the configured bandwidth. If a default class is configured with the fair-queue command, all unclassified traffic is flow classified and given best-effort treatment. If no default class is configured, then by default the traffic that does not match any of the configured classes is flow classified and given best-effort treatment. Once a packet is classified, all of the standard mechanisms that can be used to differentiate service among the classes apply. " (Cisco)

2. What takes precedence for classification of traffic, NBAR or access-list?

Inbound

Outbound

  1. QoS Policy Propagation through Border Gateway Protocol (BGP)                       (QPPB)

  2. Input common classification

  3. Input ACLs

  4. Input marking (class-based marking or Committed Access Rate                       (CAR))

  5. Input policing (through a class-based policer or                       CAR)

  6. IP Security (IPSec)

  7. Cisco Express Forwarding (CEF) or Fast                       Switching

  1. CEF or Fast Switching

  2. Output common classification

  3. Output ACLs

  4. Output marking

  5. Output policing (through a class-based policer or                       CAR)

  6. Queueing (Class-Based Weighted Fair Queueing (CBWFQ) and Low                       Latency Queueing (LLQ)), and Weighted Random Early Detection                       (WRED)

References:


Quality of Service Order of Operation
Class-Based Weighted Fair Queueing

You are welcome, I'm happy that I was able to help.  Let me know if you have any more questions.

Steve