[nsp] Stupid QoS Tricks

Christopher J. Wolff chris at bblabs.com
Tue Nov 18 00:40:47 EST 2003


Thank you, I think you are on to something.  I didn't consider this approach
but it seems the most straightforward.  With this approach any IP traffic
that hits the interface with an ip prec value of 5 gets a bandwidth
guarantee.  Can you think of any circumstances where the 3 bits of IP prec
would be stripped between two endpoints by an intermediate
router/switch/bridge?  Would using RSVP be an enhancement to this
configuration or a replacement?  Thank you for the example, this is exactly
what I needed I'm way too visual sometimes ;)

Christopher J. Wolff, VP, CIO
Broadband Laboratories

-----Original Message-----
From: Luan Nguyen [mailto:lmnguyen at cox.net] 
Sent: Monday, November 17, 2003 10:11 PM
To: Christopher J. Wolff; cisco-nsp at puck.nether.net
Subject: Re: [nsp] Stupid QoS Tricks

Maybe you should try to use Class Based Weighted Fair Queuing.  I think that
is another method of prioritizing queuing that apply to VoIP over Frame
Relay.  In this method you define classes of traffics and assign them an
absolute bandwidth that they have available during periods of congestion.
The voice queue will act as a priority queue and be serviced first.  

class-map X
  match input-interface LAN
class-map class-default
  match any 
class-map voice
  match access-group 101
policy-map WAN
  class voice
     priority Z - Guarantee bandwidth for voice class Any packet with IP
Precedence = 5 gets assigned to a class that will get a minimum of Z kbps
  class data
     bandwidth 4000
interface WAN
 bandwidth DS3
 no ip directed-broadcast
 service-policy output WAN
access-list 101 permit ip any any precedence critical

A link on how to configure CBWFQ:

Hope that help a little bit.  I am not very good at this.


> From: "Christopher J. Wolff" <chris at bblabs.com>
> Date: 2003/11/17 Mon PM 06:22:46 EST
> To: <cisco-nsp at puck.nether.net>
> Subject: [nsp] Stupid QoS Tricks
> Here's a scenario I could use some guidance on.  I've read quite a bit on
> Cisco's site but didn't find a direct correlation.  So here goes.
> Customer has a DS3, of which 4 meg is provisioned for data.  Now customer
> wants to add VOIP services.  
> Assumptions:
> - The customers' 4 meg is rate-limited by service policies / policing.
> - The 4 meg circuit is generally saturated since it is a wi-fi
> environment.
> - There is no VLAN capability on the customer LAN.
> My initial thought was to apply an ip rtp reserve to the customer
> which I did.  However it seems like there should be a better method to
> guarantee voice traffic while maintaining the customers' data 'partition'.
> Thank you in advance for your advice.
> Regards,
> Christopher J. Wolff, VP, CIO
> Broadband Laboratories
> http://www.bblabs.com
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