[cisco-voip] RE: QoS over Frame

Wed Jun 22 18:54:22 EDT 2005

A couple things I would recommend are to define the CIR at 95% of the
PVC size. This will improve on FRTS inability to consider the
Frame-Relay overhead. Also, steer clear of any oversubscription at your
hub sites. To guarantee voice quality, a consistent CIR must be defined
at each end of the PVC.

An alternate method to FRTS is to use class-based FRTS. The set up is a
bit different than in Kris's example (which works well). They differ in
that with class-based FRTS, it isn't necessary to apply frame-relay
traffic-shaping to the physical interface. With the newer method, both
shaping and queuing policies are defined in a policy-map which is
applied to the frame-relay map-class via a service-output statement.
Finally, this map-class is applied to the sub-interface via a class
statement. 

What are the advantages of this method?? It allows the shaping and
handling off individual traffic classes separately by its hierarchal
model.  It also consolidates a lot of useful info in the show policy
interface output. 

What follows is an example based on the FRTS config Kris provided.

To show the scalability, I added a small, call center op ... we want
this traffic to have its own slice of the PVC.

ip access-list extended CallCenter

permit ip 172.16.32.0 0.0.0.255 any

permit ip 172.16.33.0 0.0.0.255 any

class-map match-all agents-rtp

match ip dscp ef

match access-group name CallCenter

Class-map match-any signal

Match ip dscp  af31

Match ip dscp cs3

match access-group name CallCenter

Class-map match-all rtp

Match ip dscp ef

Class-map match-any signal

Match ip dscp  af31

Match ip dscp cs3

Here we add another policy-map for the call center agents

Policy-map CallCenter-voip

Class agents-rtp

 Priority x

Class agents-signal

 Bandwidth 12

Policy-map voip

Class rtp

 Priority x

Class signal

 Bandwidth 12

Class class-default

 Fair-queue

Now, we tie these two policy-maps together...

Policy-map TheCollective

class Agents

shape average 729600 7296 0  ! Combined shaped averages should total 95%
of PVC, or less, if I can't add  -- 

service-policy CallCenter-voip

class OtherUsers

shape average 243200 2432 0  ! Combined shaped averages should total 95%
of PVC

service-policy voip

The Map-class is a quite a bit easier to manage, since the bulk of the
work has already been completed

Map-class frame-relay voip-class

Service-policy output TheCollective

Now, bind it to the respective DLCI in the sub-interface. Remember,
frame-relay traffic-shaping isn't required on the physical interface,
with class-based FRTS.

Interface sx/x.1 point-to-point

Ip address x.x.x.x y.y.y.y

Frame-relay interface-dlci xx

class voip-class

At any rate, there's more than one way to get where your going.... the
latest way is with the use of class-based traffic shaping.

Matt Alvord | IP Migration Consultant |
Avaya | Communication Solutions & Integration | 
1800 Robert Fulton Drive | Suite 200 | Reston, VA 20191
Office: (703) 390-8324 | Mobile: (703) 625-6225 |
Email: alvord at avaya.com

Reach Avaya >> A Higher Plane of Communication <http://www.avaya.com/>

  _____  

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Kris Seraphine
Sent: Monday, June 20, 2005 9:47 PM
To: cisco-voip at puck.nether.net
Subject: [cisco-voip] RE: QoS over Frame 

Hi

I think you'll want something like this.  I'm not an expert on this so
hopefully, if there are mistakes or better ways to do this, someone will
post them and I'll learn something as well.

Create class-maps to classify voip control and rtp traffic.  You can
match a few different ways.  This simple example assumes the traffic
arrives at the edge router with the correct dscp markings.  

Class-map match-all rtp

Match ip dscp ef

Class-map match-any signal

Match ip dscp  af31

Match ip dscp cs3

Create a policy map to prioritize voice.  The amount of bandwidth
assigned to the priority queue depends on how many calls you want to
allow concurrently.  

Policy-map voip

Class rtp

 Priority x

Class signal

 Bandwidth 12

Class class-default

 Fair-queue

Create a map-class to define the pvc properties and assign the policy
created above.  Usually its recommended to shape to the cir I think.

Map-class frame-relay voip-class

Frame-relay cir 1000000

Frame-relay mincir 1000000

Frame-relay be 0

Frame-relay bc 10000

Service-policy output voip

Under the physically interface set the encap to frame and enable traffic
shaping

Interface sx/x

Encap frame-relay

Frame-relay traffic shaping

Create a sub-interface to assign the IP, pvc and apply the map-class
created above

Interface sx/x.1 point-to-point

Ip address x.x.x.x y.y.y.y

Frame-relay interface-dlci xx

Frame-relay class voip

Frame-relay class voip-class

Kris Seraphine
Senior Technology Specialist

Clifton Gunderson Technology Solutions
1111 Deming Way suite 101
Madison, WI  53717
Phone: 608.833.8638
Fax: 608.833.0194
Direct: 608.662.7640
Web: www.cliftoncpa.com <http://www.cliftoncpa.com/> 

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