Differentiated Services

 

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تعداد اسلاید (ها): 17

متن این پاورپوینت به زبان انگلیسی است.

 

چکیده ای از متن:

What is the Problem?

● Goal: provide support for wide variety of applications:

- Interactive TV, IP telephony, on-line gamming (distributed simulations), VPNs, etc

● Problem:

- Best-effort cannot do it (see previous lecture)

- Intserv can support all these applications, but

• Too complex

• Not scalable

Differentiated Services (Diffserv)

● Build around the concept of domain

● Domain – a contiguous region of network under the same administrative ownership

● Differentiate between edge and core routers

● Edge routers

- Perform per aggregate shaping or policing

- Mark packets with a small number of bits; each bit encoding represents a class (subclass)

● Core routers

- Process packets based on packet marking

● Far more scalable than Intserv, but provides weaker services

Diffserv Architecture

● Ingress routers

- Police/shape traffic

- Set Differentiated Service Code Point (DSCP) in Diffserv (DS) field

● Core routers

- Implement Per Hop Behavior (PHB) for each DSCP

- Process packets based on DSCP

Differentiated Service (DS) Field

● DS filed reuse the first 6 bits from the former Type of Service (TOS) byte

● The other two bits are proposed to be used by ECN

Differentiated Services

● Two types of service

- Assured service

- Premium service

● Plus, best-effort service

Table of contents:

What is the Problem?

Differentiated Services (Diffserv)

Diffserv Architecture

Differentiated Service (DS) Field

Differentiated Services

Assured Service [Clark & Wroclawski ‘97]

Assured Service

Premium Service [Jacobson ’97]

Edge Router

Assumptions

TC Performing Metering/Marking

TC Performing Metering/Marking/Shaping

Each domain is assigned a Bandwidth Broker (BB)

Comparison to Best-Effort and Intserv

the end

 

 

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