Connection-Oriented Networks - NC State: WWW4 Serverhp/files/Chapter1.pdf · • The switching of a...

Connection-Oriented Networks - Harry Perros 1

��

Connection-Oriented Networks: SONET/SDH, ATM, MPLS, and Optical

Networks

Harry Perros



Course syllabus • Introduction (Chapter 1) • SONET/SDH and GFP (Chapter 2) • ATM networks (Chapter 3) • MPLS (Chapters 6 and 7) • DiffServ (new material) •  Congestion Control (new material) • GMPLS - Optical networks (Chapters 8, 9, and 10) •  Virtual Private Networks (new material)


Chapter 1: Introduction TOPICS

– Classification of communication systems – Circuit-switched connections – Packet-switched connections – What is QoS? – Why do we need connection-oriented networks for

QoS guarantees?? – NGN, IMS


Classification of ��Communication Networks

Communication networks

Switched communication networks Broadcast communication networks

Circuit-switched networks Packeŧswitched networks

Connection-oriented networks Connectionless networks

•Ethernet •Packet radio network •Satellite network

•X.25 •ATM •Frame relay •MPLS

•IP network

•Telephone network •Wavelength routing network


Switched communication networks

– Circuit-switched networks: • The telephone network • Wavelength routing optical network.

– Packet-switched networks: •  IP network • ATM • Frame Relay • MPLS networks


Broadcast communication networks

•  Examples: – packet radio networks – satellite networks – WiFi – WiMax – multi-access Ethernet.


Packet-switched networks

•  Connection-oriented networks – ATM – Frame Relay – MPLS

•  Connectionless networks –  IP


Circuit-switched connections In order for two users to communicate a circuit or a connection has to be first established by the network. Specifically, the following three phases are involved: –  circuit establishment –  data transfer –  circuit disconnect


POTS: an example of a ��circuit-switched connections

Probably the oldest connection-oriented circuit-switched network is the plain old telephone system (POTS).

Twisted pair Twisted pair

Switch Switch SONET


Wavelength routing optical networks: ��a circuit-switched connection

A three-node wavelength routing network

OXC 1 OXC 2 OXC 3

λ1,..,λW λ1,..,λW

Router A Router B

λ1,..,λW λ1,..,λW

λ1 λ1

OXC 1 OXC 2 OXC 3 Router A Router B

λ1 λ1

A lightpath


•  An important feature of a wavelength routing optical network is that it is a circuit-switched network.

•  A connection is an optical path through the optical network (called a lightpath) and it is established using a wavelength on each hop along the connection’s path.


Connection-oriented ��packet-switched networks

•  Circuit switching is a good solution for voice, since it involves exchanging a relatively continuous flow of data.

•  However, it is not a good solution for the transmission of bursty data


Connection-oriented packet-switched networks imitate circuit-switched network. In order for two users to communicate a virtual circuit or a connection has to be first established by the network. The following three phases are involved: – connection establishment, – data transfer, and – connection disconnect.


A connection in an ATM network ATM

switch 1 ATM

switch 2

A B

ATM switch 3

SETUP SETUP

SETUP SETUP

CONNECT CONNECT

CONNECT

CONNECT

A bi-directional connection is established using signaling. The connection is associated with an id number.


•  The switching of a cell through an ATM switch is done based on its connection ID number.

•  A connection is associated with a specific class of service.

•  An ATM switch can distinguish cells belonging to different service classes, and serve them accordingly so that to provide them with the requested QoS.


An MPLS connection

•  The procedure is similar to ATM. •  An MPLS-enabled IP router switches IP

packets not on a hop-by-hop basis using the packet’s IP address. Rather, it forwards them using a label which identifies the connection that the packet has to follow.


Quality of Service (QoS) •  QoS describes the quality of the delivered

data by a network. •  QoS is expressed in terms of the following

metrics: –  end-to-end delay, –  jitter, and –  packet loss.

QoS metrics for common networking services


19

Conversational Voice & video Voice mail Streaming

Audio & video Fax

Remote App, Command & Control games

E-commerce Web browsing

IM FTP

(foreground)

FTP (background)

email

Tolerance for delay

Tole

ranc

e fo

r tr

ansp

ort e

rror

s

Into

lera

nt

Tol

eran

t

Interactive Delay << 1

Responsive Delay ~ 1s

Timely Delay ~ 10 s

Background Delay >> 10 s


Connectionless ��packet-switched networks

•  In an IP network, a user can send packets to a destination without having to set up a connection first, i.e., without informing the network prior to transmitting them.

•  This simplifies the network, as there is no need for a special signaling protocol.


Routing in IP

IP network

User A User B

The routing of a packet through the network is done on a hop-per-hop basis based on the destination IP address carried in the IP packet’s header.


An IP router does not offer QoS

•  It cannot distinguish packets from different applications, so that to give priority to packets that carry delay-sensitive data.

•  A packet follows a path which has the smallest number of hops. This does not necessarily provide the shortest delay, or that the jitter is bounded.

•  No guarantees for bandwidth availability.

Connection-Oriented Networks can guarantee QoS

•  It can guarantee that the network has sufficient bandwidth to carry a new flow.

•  End-to-end path may satisfy delay, jitter, and packet loss constraints.

•  Packets from a flow can be identified within a router so that they can be scheduled for transmission out on a priority basis according to their requested QoS.


24

Next Generation Networks (NGN) •  Traditional telecommunication services are

separate vertically integrated application- specific networks

•  NGN provides a single network capable of

carrying any and all services

POTS Internet TV

Circuit Switching

Packet switching

FDM

Connection-Oriented Networks - Harry Perros

25

Definition of NGN: ITU-T Y.2001 •  A IP packet-based network that provides

telecommunication services, make use of multiple broadband networks, and of QoS enabled transport technologies.

•  The service-related functions are independent from underlying transport-related technologies.

•  Supports a wide range of services •  Mobility between fixed systems and fixed and

mobile systems •  Users can freely select services Connection-Oriented Networks - Harry Perros

26

NGN Layers

Access networks

Backbone IP network

Service stratum

Transport stratum

Man

agem

ent N

etw

ork

End Users

Other networks

Third party applications providers

Application functions

Service control functions

Connection-Oriented Networks - Harry Perros

IP Multimedia Subsystem (IMS)

•  IMS was proposed originally by 3GPP for 3G cellular network, but it is now used for wireline networks as well.

•  In simple terms, IMS is a signaling protocol, based on SIP and DIAMETER, that is used in NGN to setup services.


The 3GPP IMS Architecture


AS AS AS HSS AS

Operator A Operator B

HSS AS AS

S-CSCF

P-CSCF

I-CSCF

S-CSCF

I-CSCF

P-CSCF

UE UE ... UE UE ...


Standards Committees •  ITU-T •  ISO

•  ANSI •  IEEE

•  ATM Forum •  MPLS and Frame Relay Alliance

•  OIF •  IETF


•  OMG •  Workflow management coalition

•  OASIS •  Third Generation Partnership Project (3GPP)

•  Third Generation Partnership Project 2 (3GPP •  TeleManagement Forum (TMF):

Date post:	21-Mar-2018
Category:	Documents
Upload:	doanthien
View:	218 times
Download:	2 times

Connection-Oriented Networks - NC State: WWW4 Serverhp/files/Chapter1.pdf · • The switching of a...

Documents