It is only necessary to configure QOS on the network edge device so would be the cisco router in this case. If the switch is managed you should hard code the ports to 100full to avoid clipping during link negotiation.
I suggest that you can do a speed test to verify the ISP is providing the bandwidth that is being advertised at a site like dslreports.com, since depending on how far you are located from the DSL central office the bandwidth can fluctuate greatly.
For QOS configuration, you will need to reserve ~100kb for g.711 codec and ~40kb for g.729, up/down, per simultaneous call. There are a couple of different ways to do it, something like below is simple but effective configuration ( assumes you are running SIP protocol)
class-map match-all voice-signaling
match access-group 103
class-map match-all voice-traffic
match access-group 102
!
!
policy-map voice-policy
class voice-traffic
priority 1024 <---change this number to the amount of bandwidth to be reserved
class voice-signaling
bandwidth 16
class class-default
fair-queue
access-list 102 permit udp any any range 16384 32768
access-list 103 permit tcp any eq 5060 any
access-list 103 permit tcp any any eq 5060
access-list 103 permit udp any eq 5060 any
access-list 103 permit udp any any eq 5060
Then apply this line to the WAN interface
service-policy output voice-policy
Main Topics
Browse All Topics
by: rpalmeira22Posted on 2008-01-15 at 12:22:30ID: 20666115
before you even get to the QoS, couple of things to determine
1. how many phones do you have?
2. how many simaltaneous calls do you have?
3. what kind of DSL do you have? If it's ADSL, what is your upload speed? This will be the limiting factor. you may have 1.2 Mbps down but only 256 Kbps up
4. does your ISP offer QoS through their netework? If so, what methods do they use for QoS? IP Precedence? DiffServ? tosbit? DSCP?
Starting from the phones and moving up to the WAN
a. What codec are you using on the phones? G.729 is generally acceptable for calls and will minimize bandwidth usage.
b. Do you have the phones on their own VLAN?
c. Determine what kind of method you want to use for QoS. This can be based on what the phones support, or perhaps what your ISP will look at for QoS marking. It doesn't make much sense to mark packets within your network if your ISP will ignore them
d. Do you have access to modify the settings on the Cisco 800 series router? or jus the zywall?