Quality of service models:
- Best-effort service
- Integrated services
- Differentiated services
Best-effort service model – the internet was initially based on a best-effort packet
delivery service. Best-effort is the default mode for all traffic. There is no
differentiation among types of traffic.
The best-effort model is similar to
using standard mail service – it will get there when it gets there.
Advantages of best-effort service
model:
- Highly scalable
- No special mechanisms required
Disadvantages of best-effort service
model:
- No service guarantees
- No service differentiation
What is Quality of Service (QOS)?
What is Modular Quality of service CLI (MQC)?
What is Classification and marking? What are IP Precedence and DSCP Values? What is AF and EF?
What is of NBAR (network- based application recognition), classification QOS How to configure NBAR?
Integrated services (intserv model) are a QoS model that is older than QOS /
Differentiated services model. Intserv model defines a signaling process by
which an individual flow can request that the network reserve the bandwidth and
delay needed for the flow.
The integrated services model uses RSVP
for reserving bandwidth. RSVP stands for a resource reservation protocol.
RSVP is used for reserving bandwidth/QOS tools for a particular
flow.
Here is a limitation of intserv model
if reserved no other traffic can use it and it is not scalable each flow
required separate admin configuration on the router.
The differentiated services model is designed to overcome the limitation of best-effort
and intserv models. In Diffserv model network traffic is identified by classes
and network QOS policy enforces differentiated treatment of traffic classes.
You choose the level of service for each class.
Advantages of Differentiated service
model:
- Highly scalable
- Many levels of quality are possible
Disadvantages of Differentiated
service model:
- No absolute service guarantee
- Complex mechanisms
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