Need Help with Voip and QOS

[marslove]

Hi Guys
I get Time Worner Cable 9 M down 386k Up with 5 Voip extensions
Cisco 831 router all internal devices behind NAT
I need help to write proper QOS strategy

Thanks a Lot

 

[unclerico]

can you tell us a little more about your setup?? is this 831 connected via L2L VPN to another LAN segment??

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[marslove]

Its very simple setup
ISP-->831-->LAN
LAN is behide NAT

Thanks Again

 

[VinceWhirlwind]

Does your ISP offer Classes of Service?
If not, the only thing worth doing at your end would be to apply a bandwidth restriction on your outgoing traffic on your router, prioritising RTP traffic.
Your incoming traffic can't be helped from your end though, and seeing as most traffic overall will be incoming, not outgoing (web-browsing) it's the incoming you most need to protect.

 

[marslove]

I am new to Cisco. What the script to prioritizing RTP traffic would look like

Thanks

 

[VinceWhirlwind]

First, check what your upstream bandwidth is.

Then, review this for traffic-shaping:

http://www.cisco.com/en/US/docs/rou...re/configuration/guide/advconf.html#wp1101354

The config. example it gives is this:

class-map match-all voice
match ip precedence 5
[check how your handsets are tagging the traffic. You might have to try something different, eg "match ip rtp"]

policy-map LLQ
class voice
priority 300
[check your codec - multiply whatever bandwidth it needs(incl. overheads) by 5 for the figure you need here]

class class-default
fair-queue

policy-map shape
class class-default
shape average 2250000
[your upstream bandwidth]
service-policy LLQ

interface Ethernet1
ip address 192.168.1.101 255.255.255.0
service-policy output shape