Router QoS

A question about the 'Quality of Service' factor in routers.
Is the purpose of QoS to prioritise 'voice' over that of other data
signals in order to maintain quality?
If this is so then if a router doesn't have QoS, but no other data is
being transmitted, is QoS relevant - i.e. without any other data does
QoS make any difference?
Remove 'no_spam_' from email address.

"Brian A" <no_spam_bca1000@hotmail.com> wrote in message
news:0cnkg11e3gvbrofptuc283dhv58s332v95@4ax.com
> A question about the 'Quality of Service' factor in
> routers.
> Is the purpose of QoS to prioritise 'voice' over that of
> other data signals in order to maintain quality?

Yes.

> If this is so then if a router doesn't have QoS, but no
> other data is being transmitted, is QoS relevant - i.e.
> without any other data does QoS make any difference?

No.

Ivor

QOS will only work in one direction in the case of DSL or Cable, since
you can only control outbound to your provider

So is one way QOS of any use??? is the question

>>> Brian A<no_spam_bca1000@hotmail.com> 23/08/2005 00:23 >>>
>A question about the 'Quality of Service' factor in routers.
>Is the purpose of QoS to prioritise 'voice' over that of other data
>signals in order to maintain quality?
>If this is so then if a router doesn't have QoS, but no other data is
>being transmitted, is QoS relevant - i.e. without any other data does
>QoS make any difference?
>Remove 'no_spam_' from email address.

QOS on the Internet is different to QOS on LAN/WAN links. On the Internet you can't controll the priority of your data once it's left your connection so the QOS in this case is the router giving the voice priority at the expense of data, your ISP just sees it as a stream of data and can give you no guarantee of bandwidth. On a LAN/WAN link you can configure your networking equipment to recongnise voip traffic and guarantee bandwidth for it from end to end. I know some ISP's will allow QOS on leased line Internet connections but they cost loads of money.

Shane

"Brian A" <no_spam_bca1000@hotmail.com> wrote in message
news:0cnkg11e3gvbrofptuc283dhv58s332v95@4ax.com...
> A question about the 'Quality of Service' factor in routers.
> Is the purpose of QoS to prioritise 'voice' over that of other data
> signals in order to maintain quality?

that is just one case - QoS is about giving preference to some traffic, and
possibly limiting how much preference it gets.

at work often different types of data flows get different priority, and IP
telephony traffic gets handled specially.

The flip side is that you may have to limit how much high priority traffic
is allowed - since it can starve other traffic of bandwidth if you dont.

finally sometimes voice isnt highest priority - i suspect a broadcaster for
example cares more about sending out a TV channel than an employee ringing
home to explain they might be late.....

> If this is so then if a router doesn't have QoS, but no other data is
> being transmitted, is QoS relevant - i.e. without any other data does
> QoS make any difference?

QoS works in practice within a router by manipulating queues of packets, and
maybe by delaying packets. Basically the QoS schemes choose which packet
goes next. So - if there is only ever 1 packet pending for an outbound
interface, QoS isnt going to make much difference.

However the end to end QoS schemes like Diffserv involve marking each packet
with its specific priority level.

So - if the downstream devices understand Diffserv, if they are configured
to use the markings to give priority to some packets, if no device
downstream of yours alters the packet markings, and if you chose the right
markings - then altering QoS markings in your packets when they leave your
PC or router may make a difference.

QoS is becoming more common in enterprise WANs - often multiple QoS levels
for different types of data traffic, and sometimes Voice over IP as well.

but the default across most of the Internet is that QoS is either ignored,
or that non trusted streams or packet sources have their packets marked for
default handling. So the typical case on the internet is that QoS markings
dont make any difference.

> Remove 'no_spam_' from email address.
--
Regards

Stephen Hope - return address needs fewer xxs