QoS

[Ladislaus]

Hi!

We have a Cisco 3660 and a ADSL line (2Mbit/s download, 0.5Mbit/s upload) over here. We recently added VoIP to our site. It works great since we just use it for internal communication, when going out it goes straight to a PSTN Gateway.

We also have some people working from home, recently, there has been a suggestion to equip these with IP telephones so that they may call via the companys VoIP system. So I made a simple test, I brought a phone home with me and just as I suspected there was trouble due to high latencys. I suspect this is due to ACK packets not getting through. For example, if I send at 0.5Mbit/s I can not receive more than a few kb/s, when lowering the upload speed to somewhere slightly less than 0.5Mbit/s I can download at near 2Mbit/s. So it seems as if ACK packets are not getting through. And since my voice calls are tunneled (using tcp packets), the VoIP calls are kind of 'laggy'. I need to prioritize ACKs from the office towards the Internet. But how?

I've been advised to use CBWFQ and so I have tried but with no success.

Please give me an example configuration.

Regards,

Kristian

[aacole]

The problem you will run into is the lack of support for QoS in the public Internet.

Although you could classify and mark traffic entering the Internet over the ADSL link there is no guarantee that the marking will be acted on. The same applies for any fragmentation and Interleaving for the RTP streams, whilst this could be set up locally you have no control over the ISP routers, so any benefit is negated as soon as the traffic hits the next hop router.

[Ladislaus]

I assume they have ample bandwidth to take care of this once it reaches there network. The problem is to get there. I am certain that the problem lies with us.

I have prioritized ACK packets before, though then with a computer running OpenBSD, it really made a huge difference. However I am not able to get this going with my cisco.

Please, anyone with a sample configruration!?

[rpgccie]

Yes as aacole says

QOS has to be end - end..

when it come to the internet ou need to have QOS

in your SLA with your ISP...and the end point has to be where youre trying to reach from currently..

or you cannot achieve the maximum out of it.

[asafayan]

I don't agree with aacole or rpgccie that you MUST have QoS end-to-end. That would be great in a world where money is no matter. But for most folks, you need to impose some QoS getting on and subsequently getting off the Internet. Those are the two choke points - not some big pipes in a telco backbone.

I have two 831's ( I think that is the model) to perform pilots for our 50 or so telecommuters to both VLAN and VoIP back into our corporate network.

It's worth a try.

[jasosmith]

In my experience you, this conversation really centers more around expectations than whether you need QOS end to end. I have seen both. If these are internal calls and the expectation is that every now and again the quality may suffer, then I say go for it (at least pursue it). If on the other hand, the people working from home face the customer, I would shy away from it.

I have weekly conference calls with telecomuters using soft phones over the public internet and with the exception of the occasional garble, it works very well.

Just my $.02

[asafayan]

Well said jasosmith...you are correct. In our situation, occasional hickups are fine. For those who need 100% accuracy...QoS end to end is needed.

Regards