Frame Relay Access Link to MPLS Cloud QoS Design

Answered Question
May 2nd, 2007

I am trying to design a QoS strategy for our WAN. The majority of our remote sites use 1024k links with Frame Relay encapsulation out to a service provider managed MPLS cloud.

The question I have is how QoS should be implemented on these links. In reading the Cisco QoS SRND Guide, it states that Frame Relay links at this rate fall under the Medium specification. According to the guide it says to set the following:

CIR: 95% of PVC contracted speed

Bc: CIR/100

Be: 0

minCIR: CIR

So the question is, since this is just an access link and not a traditional Frame Relay network, should I still implement shaping? And if so should it just be on the class-default?

Please Help! Thanks.

Correct Answer by royalblues about 9 years 9 months ago

I think a nested policy should be the best option for you.

policy-map voice

class voice

priority percent 10

set ip dscp ef

compress header ip rtp

class signalling

bandwidth percent 1

class critical-data

bandwidth percent 34

class bulk

bandwidth percent 34

class class-default

fair-queue

policy-map CB-shaping

class class-default

shape average 102400 1280 0

service-policy voice

interface serial 0/0

service-policy output CB-shaping

HTH, rate if it does

Narayan

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Overall Rating: 4.3 (3 ratings)
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royalblues Wed, 05/02/2007 - 07:53

Friend,

Please elaborate what QoS are you planning to deploy in our network, Voice?

Shaping can severly affect voice performance

Also you need to check what QoS policies your service provider is running on his MPLS. Since the connections are not end-to-end deploying QoS at your end may not help once it goes into the MPLS cloud. They need to trust your markings

HTH, rate if it does

Narayan

mlitka Wed, 05/02/2007 - 08:00

I am planning on deploying the 5 class model in the following way:

1. Voice

10% Bandwidth Guarantee

RTP Compression

Low-Latency Queue

2. Call Signaling

1% Bandwidth Guarantee

3. Critical Data

Weighted Random Early Detection - DSCP Based

30% Bandwidth Guarantee

4. Bulk

34% Bandwidth Guarantee

5. Best Effort

Fair Queuing

My provider defines 5 traffic classes that these will map directly into.

Correct Answer
royalblues Wed, 05/02/2007 - 08:14

I think a nested policy should be the best option for you.

policy-map voice

class voice

priority percent 10

set ip dscp ef

compress header ip rtp

class signalling

bandwidth percent 1

class critical-data

bandwidth percent 34

class bulk

bandwidth percent 34

class class-default

fair-queue

policy-map CB-shaping

class class-default

shape average 102400 1280 0

service-policy voice

interface serial 0/0

service-policy output CB-shaping

HTH, rate if it does

Narayan

mohammedmahmoud Wed, 05/02/2007 - 08:48

Hi,

I think that the nestted method is the best but the only problem is that you can't set in 2nd level policy-map, and accordingly you can put the Classification and Marking policy map as in input policy map on the LAN interface.

You'll get this error:

'set' command is not supported in a 2nd level policymap

HTH, please do rate if it does help,

Mohammed Mahmoud.

mlitka Wed, 05/02/2007 - 10:06

As this is a frame relay interface, wouldn't I put this on the point to point serial subinterface under the frame-relay interface dlci x statemnt?

royalblues Wed, 05/02/2007 - 10:13

yes you are right

the policy needs to be applied under the subinterface carrying the DLCI information

HTH, rate if it does

Narayan

mohammedmahmoud Wed, 05/02/2007 - 10:15

Hi,

It can be added under the PVC or the subinterface, it won't matter in your case, but the classification and marking one should be don on the Ethernet LAN interface.

HTH, please rate if it does help,

Mohammed Mahmoud.

mlitka Wed, 05/02/2007 - 10:17

OK. Thanks for the info. The real question here though is how to address the shaping issue. Since this is a frame relay link, shaping should be done per the QoS SRND Guide. Where would you put the shaping in the policy?

mlitka Wed, 05/02/2007 - 10:23

I didn't mention policing. I asked where in the QoS Policy would I put the shaping piece.

mohammedmahmoud Wed, 05/02/2007 - 10:32

Hi,

Sorry :) The nestting example that Narayan has given above is perfect, where 2 policies are nestted in each other:

policy-map voice

class voice

priority percent 10

compress header ip rtp

class signalling

bandwidth percent 1

class critical-data

bandwidth percent 34

class bulk

bandwidth percent 34

class class-default

fair-queue

policy-map CB-shaping

class class-default

shape average 102400 1280 0

service-policy voice

interface serial 0/0

service-policy output CB-shaping

If you require classification and marking, you'll have to do it via a separate policy for the incoming traffic on the ethernet LAN.

HTH, please rate all helpful posts,

Mohammed Mahmoud.

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