So what is the Cisco quality of service toolset.
The S.R. indie guy discusses the following mechanisms or quality of service tool sets that allow you
to implement quality of service.
This is what is emphasized in the CCMA exam.
The exam talks about marking device trust.
Pro translation shaping policing and congestion management.
And if you look at the mechanisms listed in the s or indeed guide we have classification and mocking
policing and markdown scheduling link specific tools and there are some additional options such as order
cause and called Mission Control.
He has a graphic showing the quality of service toolset.
Now these mechanisms apply to differentiate its services or serve into serve has its own mechanisms
and best effort.
Essentially it doesn't have these mechanisms.
It simply treats all traffic the same.
Firstly we have a mission control.
Will your call as an example be permitted across the IP network.
If there is over subscription of the link a voice call may need to take an alternate path classification
and marking is essentially looking at traffic types and putting them into classes.
So is it voice traffic.
If it is then it goes into a certain class.
Is it video traffic then it would go into a different class.
Is it FCP FCP would go into a third class.
We have policing and markdown.
If you're sending too much traffic your traffic could be dropped or the quality of service given to
you could be lowered.
Then we have scheduling which includes queuing and dropping.
We have traffic shaping and link specific mechanisms we'll start off with classification and marking.
When you send a package with FedEx or DHL that package needs to be marked for next day delivery or urgent
delivery or standard delivery a label gets put onto the package to indicate how important that package
is when the package is sent from one depot to another.
They don't open the package to determine the quality of service that that package would get.
They look at the label and the label determines the quality of service that the package gets in the
same way when a telephone sends packets into a network.
It needs to mark those packets as important so that every switch and router along the path can treat
the packet differently when compared to say FCP sent by.
P.S. so when packets are forwarded from the phone to the first switch it needs to indicate using some
kind of marking or label or field that the packet is important.
It needs to be treated better than say in FTB packet when switch one sends the packet to switch to it
needs to indicate to that switch that the packet is important and in the same way when the second switch
sends the packet to the rudder it needs to indicate to the broader that the packet is of great importance.
Now this introduces the concept of a trust boundary.
Who do we trust in the network.
As an example does the rod of trust switch to the switch to trust.
Which one as an example.
If these devices trust the markings that they receive from each other or the quality of service settings
that they receive from one another then the trust boundary ends over here.
In other words the switch doesn't trust the phone and the switch doesn't trust the P.C..
If however the switch did trust the phone the trust boundary would be extended to the phone as is the
case with a lot of IP phones.
We could have a P.C. connected to a phone so we could connect to the P.C. to the back of the phone and
in that case the trust boundary would end at the phone.
In other words the switches and the router trust the phone but they don't trust the P.C..
So if the P.C. sends traffic to the phone telling the phone that its traffic is important the phone
will not trust those markings.
All those values and would override them in the same way switch one doesn't trust the markings or values
sent by the P.C. but it would trust the markings or values sent by the phone and again switch to would
trust what switch one tells it and the writer would trust.
Switch to as an analogy if you go to the airport and your ticket says that you have a first class ticket
you will be treated differently to someone who has a economy class ticket.
But the people at the airport won't accept a ticket that you've just made up.
So if you just printed out your own ticket they're not going to trust that unless they can reference
it officially.