QoS configuration

[andybrogi]

This is my network scenario:

-a DSL access to the Internet that works properly.

-a PBX based on Asterisk and many Ip-phones. The signaling protocol used is SIP.

-a SIP account to a SIP Proxy on the Internet. In this way the PBX could receive incoming calls from the PSTN and place outgoing calls to the PSTN.

-many workstation attached at the same LAN segment.

Now I've realize that sometimes Voip calls quality it's not good.

So I'm trying to implement QoS (CBWFQ) on the 837 (IOS 12.4) that share Internet access. Here's a part of the configuration. In particular the main purpose is to reserve at least 128 Kbit/s to support at least 4 VoIP calls (the codec used is g.729).

class-map VoIP

match access-group 102

policy-map VoIP

class VoIP

bandwidth 128

interface atm 0.35

....

bandwidth 2048

.....

.....

.....

service policy output VoIP

access-list 102 permit udp any eq 5060 any eq 5060

access-list 102 permit udp any range 60000 65000 host <ip address SIP proxy>

So I try to check my configuration with this command:

show policy-map interface atm 0.35

but I see that all VoIP traffic is matched as class-default.

What's wrong?

Thanks in advance.

[johnnylingo]

Ah ok. Just FYI Cisco recommends you match using DSCP or IP Precedence when possible, just in case the port is not know or changes.

Just curious, what does "show int ATM0.35" look like? I noticed you have a max of only 40 conversations on that interface. On my 831 with the same config, I have 264 but that of course is Ethernet.

[andybrogi]

Hi johnnylingo,

Do you think that my voice problem is due to the conversation limit in the queue?

I really don't knowk what to do..

[andybrogi]

Hi,

I'm trying to implement your solution.

Router accept the command "shape average 2048000" but this command not appear if I type a "show run".

Moreover the router accept the "service-policy output VoIP" in the atm-sub-if but this command also not appear in configuration after a "show run".

Moreover no information about queue are displayed with a "show policy-map inetrface atm 0.35"

Any other ideas?

Thanks for all.