[c-nsp] VOIP/QOS

Paul Stewart pstewart at nexicomgroup.net
Mon Mar 13 15:59:40 EST 2006


Thanks Scott...

Do I have to put a bandwidth allocation in place if I'm not worried (in
this particular case) about congestion?

It's a 100 meg FE connection with media converters via fiber from
customer location back to us. ;)

All the best,

Paul


-----Original Message-----
From: Voll, Scott [mailto:Scott.Voll at wesd.org] 
Sent: Monday, March 13, 2006 1:19 PM
To: Paul Stewart
Cc: cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] VOIP/QOS

Paul--

You're close.  You match the traffic in the class-map which is correct.

The Policy map you need to setup your bandwidth allocations.

IE> 
Policy-map SIP
 Class VoIP
   Priority 480 (setup 480k FIFO)
 Class class-default
   Fair-queue

This will put the SIP traffic FIFO and everything else will queue after
it.

I see the description says WAN but it's a FE interface.  Which are you
trying to do?

For my local LAN I setup a Cos for layer two

IE>
Policy WAN2LAN
 Class VoIP
   Set cos 5

Then you can use your switches to prioritize at layer two based on cos.

Hope that helps.

Scott

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Paul Stewart
Sent: Monday, March 13, 2006 9:25 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] VOIP/QOS

Hi there...

I've finally had a few minutes to start exploring our entire network
with the hopes of prioritizing/optmizing VOIP based traffic.  After a
lot of reading, I'm not sure which methods to use.  My first question is
in regards to what common practice is with everyone on the list.  My
issues are not around congestion (generally speaking) - I want to make
sure however that any SIP based traffic flows arrive before everything
else does basically...

At this point, I've figured that "ip precedence" will help me with this
.. Am I heading down the wrong path?

Here's a config I'm workig with this morning (cisco 3640 at a customer
site that is using SIP):

class-map match-any VOIP
  description SIP Prioritization
 match protocol sip
 match protocol rtp
 match protocol rtcp
!
!
policy-map SIP
 class VOIP
  set ip precedence 2

interface FastEthernet0/0
 description WAN 1
 ip address xx.xx.xxx.98 255.255.255.248  ip nbar protocol-discovery  ip
route-cache flow  load-interval 30  speed 100  full-duplex
service-policy input SIP  service-policy output SIP


Is this wrong?  Seems a little too simple and/or does this even
accomplish what I want to do?..;)  any input would be appreciated...
Sorry if this is QOS 101 but we've never had a reason to worry about QOS
before and now I'm concerned with real-time VOIP etc. that we shouuld be
concerned...

Paul Stewart
IP Routing/Switching
Nexicom Inc.
http://www.nexicom.net/ 

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