Now before traffic policies can be applied to packets the packets need to be put into a class so as
an example before you're allowed to take a first class seat someone checks your ticket to ensure that
you are a first class passenger.
So in other words before quality of service is applied to your packet the rod or switch needs to determine
which class you belong to.
If you belong to the platinum class you will get a platinum service but if you belong to the economy
class you'll only get an economy service.
But before the service is applied the Rado switch needs to determine which class you belong to and it
can do that as an example by looking at the marking a FedEx sorting depot will sort packets based on
the marking on a package packages with next day delivery or high importance will be processed differently
to packages that have standard delivery markings on them.
Best practices state that you should classify and Mark as close to the edge of the network as possible.
So as an example IP phones will mark their traffic as it leaves the IP phone for other traffic types
you want to try and do your classification and marking on your age switches so marking takes place on
the edge.
But every device along the path uses classification to determine what quality of service that traffic
gets.
It can do the classification based on three criteria either by looking at the marking in a header such
as the costs or DSP value.
It could also look at IP addressing such as the destination IP subnet that you're going to or source
IP address or layer to MAC address or some other addressing criteria.
So as an example it could look at destination port number.
Are you going to a specific IP address and specific port number or are you going to something like Cisco
dot com vs. Facebook dot com.
So a domain address in addition routers can support deeper payload inspections by using application
signatures.
So by using network based application recognition or Anbar a writer can look deep into a package to
determine how important that traffic is.
So Inbar uses layers 47 for deep packet inspection.
It is more CPA intensive and therefore you generally only do it at the edge of your network.
Most applications can be identified using Layer 3 will layer for criteria such as IP addresses or well-known
port numbers but other applications require deeper packet inspection.
As an example HDP uses port 80.
You don't want your riders classifying traffic going to Cisco dot com in the same way as Facebook dot
com.
Both of them could be using port EDI or port FL for 3 h GDP s so you may need to look deeper into the
packet to determine where it's going.
So as an example look at the domain name and then do your quality of service based on their destination
domain name.
Inbar supports two modes of operation we have passive mode and active mode passive mode provides real
time statistics on applications per protocol per interface and gives bi directional statistics such
as bitrate packet and byte counts.
Active mode classifies applications for traffic marking so that quality of service policies can be applied.
So are we actively looking at traffic types and then applying quality of service.
Or are we just reviewing statistics of traffic going through a network so passive mode provides statistics
but doesn't do marketing active mode allows you to do markings and apply quality of service policies.