communication networks – ii lecture 12 advanced computer networks (acn) 545

Mr. Thilak de Silva.BSc. Eng., MSc, CEng, FIE(SL), FIET(UK), CITP(UK), MBCS(UK), MIEEE (USA)

M.Sc. in IT - Year 1 Semester II - 2012

NetworksTransmission NetworksLTEMultiplexes

M.Sc. in IT - Year 1 Semester II - 2012

At the end of this session you will understand about the Networks, LTEs, Multiplexes and their management systems.

M.Sc. in IT - Year 1 Semester II - 2012

Networks can be divided in to three main types.

Access Networks.▪Wired▪Wireless

Switch Networks.

Transmission Networks. M.Sc. in IT - Year 1 Semester II -

2012

There are two main factors in Transmission networks.▪Transmission Media▪Transmission Technology.

M.Sc. in IT - Year 1 Semester II - 2012

One type of transmission media is Fiber.

Fiber should be terminated from a special equipment named LTE – Line Terminal equipment.

M.Sc. in IT - Year 1 Semester II - 2012

LTE LTEFiber

Including supervisory signals to supervise the end to end line.▪ Eg:- if a repeater is faulty it should be identified.

M.Sc. in IT - Year 1 Semester II - 2012

LTE LTE

Fiber Line

Repeater

Repeater

Suitable encoding of bit patterns. Eg:- Manchester Encoding

AMI CMI

Media Conversion (if necessary) Eg:-Electrical to Optical Conversion

M.Sc. in IT - Year 1 Semester II - 2012

M.Sc. in IT - Year 1 Semester II - 2012

All transmission networks terminates at LTE.

Need supervisory signals to monitor the link.

If one link is out of order or if a particular link is having high traffic the LTE finds an alternate link to send data.

This is the management part of the media.

M.Sc. in IT - Year 1 Semester II - 2012

Graphically represents all the LTEs and respective links between LETs.

Transmission media management can be done in a separate, central location.

This is for fiber optics.

Most of these software are pro-priority.

M.Sc. in IT - Year 1 Semester II - 2012

M.Sc. in IT - Year 1 Semester II - 2012

Telephone lines are connected to MUX.

Multiplexes are connected directly to LETs.

Logically Muxses forms a separate network but actually data are sent through the LETs.

M.Sc. in IT - Year 1 Semester II - 2012

Eg:- SDH (ITU-T standard)▪SDH includes a management system too.

Theses Multiplexes also has a separate management system, to divert the traffic in a failure of a link, to an alternate link.

M.Sc. in IT - Year 1 Semester II - 2012

From these two fiber restoration is done immediately. (LTE Restoration)

Only if the fiber is slow, SDH will do the restoration. (Multiplexes Restoration.)

But Fiber management software is expensive and not used in countries like Sri Lanka.M.Sc. in IT - Year 1 Semester II -

2012

Similar concept is used in switches.

Physical Layer, SDH layer and switches has separate management systems.

M.Sc. in IT - Year 1 Semester II - 2012

M.Sc. in IT - Year 1 Semester II - 2012