Hi,
I have 2 Cisco 2821 routers with 3 T1's per router and each router on a separate ISP. Traffic is per packet load sharing on each router and both sides are live. I have an Asterisk Appliance running SIP phones on a Vlan inside my network with the outside interface of the Asterisk Appliance connected to my SIP provider. What is the best way to go about QoS configuration for this scenario and on what interfaces would I apply my policies. I have the SIP phones (Polycoms) on 3 Dell Powerconnect 3448 switches on their own VLAN. I want to configure QoS on these as well.
------Cisco 2821-----------ISP A
|
IP Phones-------Switches-----
|
-----Cisco 2821----------- ISP B
Configuration examples would be awsome.
Thanks,
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The Asterisk can mark the packets as far as I know so is it best to do it at the Asterisk box or the switch? Also do I need to know what type of marking my SIP provider supports? And also (sorry) what about the policies for the routers? Do I need to apply the policies to the multi link interfaces or the inside interfaces or both on the router?
You will need to know how Asterisk is marking the traffic, or if you do not know, re-mark the traffic as they enter the switch.
Yes, you need to know what marking your SIP provider supports, by default 'EF' is the highest DSCP marking reserved for voice traffic, confirm from your SIP provider if they are following the standard and also if they are granting EF traffic the highest priority in their network, once you know that, re-mark all your SIP traffic at the switch entrance as EF.
If you know that your asterisk is already marking these traffic as EF, simply configure your switch to trust this marking.
When applying the QoS policy, I will be concern more about the interface that connects to my ISP and apply the policy in both direction on that interface.
There will be no need applying the policy on the interface that connects to your LAN, you already have 100M/Full duplex on that interface and there might be little or no contention for bandwidth on that interface, your WAN link having about 3Meg is where the contention lies.
However, if you so choose you can still apply it on the LAN interface, but the most important one is the outgoing interface to your ISP.
On the router, you have to apply the police on the interface that have the IP address and in your case that will be the multilink interface.
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by: oletuPosted on 2007-12-18 at 08:22:24ID: 20493266
It is better to mark the voice traffic at the access level i.e. at the switches and assign them to a priority queue at the switch. At the switch your priority direction should be outward.
As the Voice traffic enters & leaves the router, you will still have to configure QoS to obey the markings that you have done at the switch and ask the routers to equally give those markings a priority.
As you might have known, QoS is an end-to-end thing, so to get the best out of QoS, all your routers must be able to resognize the markings and obey them, which means you might have to configure QoS all the hop routers from the source of SIP to the destination.
If you need further assistance, please let me know.