Quality of Service - has it found its voice?

In the final part of our Quality of Service (QoS) interview series, Ian Yates and HP's Fotios Kotsiopoulos consider QoS and VoIP

PREVIOUSLY: Will QoS work for smaller networks?

Ian Yates: Okay we are looking at quality of service issues and you have all seen those buttons inside your router menu that say activate quality of service but maybe you have wondered what does it do and would it work and if it was not in agreement with everybody else in the universe is it going to make any difference to your networking. Thaddeus, what do you think about that?

Fotios Kotsiopoulos: I think absolutely you need to look at it and depending on the applications that you deploy on your network you may need to enable QoS especially for applications for VoIP or video conferencing.

IY: Yeah I understand the voice and video are the kind of places where it obviously, you know you want quality of service because you want to make sure you have got your share of the bandwidths that is available to keep it working. But, don't you need it on every device, does it help if you have only got it inside your network, doesn't the upstream ISP type people have to have it too?

FK: That's correct. QoS really needs to be implemented end to end. It needs to have total control of the packet, there is no point enabling QoS at that starting point and then somewhere along the line that application hits a bottle neck. So it is good to discuss with your ISP whether they are able to provide that level of service.

IY: Increasingly are they? I mean is the answer yes a lot more then it used to be?

FK: I believe it is, but you need to actually look at how much bandwidth you are going to require and what type of applications you are going to performing, so it really has to looked at on a case by case basis.

IY: Okay, of course, if it is inside your own company, from building to building or across or campus or between floors of course you can guarantee it because you own the box at each end and you can activate it, yeah.

FK: Of course, QoS is very effective on a local area network where there is typically lots of bandwidth available and where you have got total control of the network. But a lot of customers these days are deploying just more bandwidth to overcome these issues.

IY: Yeah right. Instead of using the quality of service to sort of make maximum use of the bandwidth they own.

FK: Yeah, I guess there are certain latency issues though that you need to look at, especially with voice, bandwidth is not always the answer. If you know you really want to provision not only enough bandwidth but ensure that there is always a clear path for your voice traffic to cross the starting point from the ending point of the conversation.

IY: Right, in as much as of course that you can control that, I guess, inside the company, I guess you start to be at the mercy of the ISPs et cetera when you leave the building.

FK: Exactly once it hits that big cloud out there you are at the mercy of the ISP. So depending on that service level agreement you have got with your ISP it may or may not be appropriate for the type of application you want to deploy.

IY: I guess from what you are saying it sounds to me it is amazing that VoIP actually works.

FK: Well VoIP actually only needs a very small amount of bandwidth, only about 100 bytes.

IY: Okay.

FK: Kilobytes I should say.

IY: That emphasis the point you were making earlier that people just jumping up the bandwidth trying to save them - trying to improve their VoIP quality may not be getting themselves very far.

FK: Exactly and I guess it really depends on if you are deploying VoIP across the web link as a main replacement to your traditionally analogue PABX type service, well then you might want to ensure that you have got certain level agreements established with your ISP. If you are just toying around with the idea, you have only got a couple of hand sets across a LAN link you will probably find that it works okay. But once you start having hundreds of concurrent phone calls being deployed at the same time, that is where you really need to start looking at QoS.

IY: Yeah I guess you would also be starting to get close to chewing up a fair bit of the bandwidth inside your LAN wouldn't you, if you start doing that?

FK: Absolutely and that is another reason they are seeing a great uptake in 10Gig as well.

IY: Oh really?

FK: Traditionally in the past you would find hundred megabyte on the edge of your network and the next stage everyone is going down and changing up-links with gig support at the edge of their network.

IY: Yeah right. Because I mean in the past those phones used to work on their own. Nice piece of cooper but these days they are jamming themselves in there alongside your data packets.

FK: Yeah exactly. That is what you are actually seeing IP handsets with gigabyte ports on them these days.

IY: Gigabyte, okay.

FK: Even though the actual handset will never use that gigabyte port for an IP voice packet, you still need to allow the PC that is hanging off the end of that phone to communicate via gigabyte speed across the network.

IY: Yeah. Good grief. Oh well, and that is going to get worse because hey look at this communications, we are all putting video on the desktop as well.

FK: Yep, absolutely, other applications, not only voice, but video and also when you deploy wireless over your local area network that wireless traffic will hit your local area network and needs to be provisioned accordingly.

IY: Okay. Of course you could also choke your wireless network if you put in too many of these VoIP handsets that run off wi-fi.

FK: Yeah there is not reason why you could not prevent someone from running voice or even video across their wireless or - that is why we are seeing a bit of an uptake on the that side of things as well.

IY: Yeah so there is no free lunch, I mean you might get rid of one side of the things, you might get rid of your traditionally PABX but suddenly your IT dude becomes a phone manager and they may not be all that experienced in phone management.

FK: Yeah that is one are where a lot of IT staff are familiar with data but when you throw voice into the equation it could be a totally new challenge for them. Again when some is traditionally got a voice background and now all of a sudden that application has been converged on the data network, it could be quite a challenge for them to move over to the data side.

IY: Yeah. All right, plenty of things to look out for there but as you say that QoS button is there for a reason, investigate it and see if it can improve your network.

FK: Absolutely.


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