FDDI and ISDN

-Vivek Jeena

Timeline : Presentation

• FDDI: What it is?

– Basic Principle’s

– Physical Properties

– Architectural Model

– SMT PMD Layer

FDDI: Introduction

• FDDI: Fiber Distributed Data Interface(ANSI) • October 1992: By JAMES HAMSTRA at SPERRY(Now

UNISYS)

• Fiber Optics: Edge of 100Mbps

• Uses IEEE802.4 timed token

• Logical topology : Ring Based token Network

• “Dual Ring of trees”

• Primary ( Clockwise) and Secondary(Anti-clock wise) Rings.

FDDI: Basic Principles

• Uses TOKEN: a special sequence of bits.

• Token Circulates in the ring.

• No Collisions.

• During transmission token is captured by a node

and released after transmission.

• STANDARD: Secondary ring is kept for backup

How Token Moves

FDDI: Architecture

FDDI: SMT Layer

• OSI-RM’s Physical and Part of Data Link Layer

• SMT: Station Management- MAC,PHY,PMD

• SMT : Process in FDDI Device.

• PMD : Physical Medium Dependent

• PMD: Deals with Type of Media Interconnection and Physical Characteristics.

• PHY: Media Independent functions, uses 4B/5B Encoding Standard.

FDDI:Pro’s and Con’s

• Con’s:

– Higher Cost and Maintenance

– Professionals are needed to troubleshoot

• Pro’s:

– Higher Bandwidth

– Lower Attenuation

– Difficult tapping

– No collisions

ISDN: Introduction

• Integrated Services Digital Network

• Simultaneous Transmission of voice, data over PSTN

• Circuit Switched Network(Voice and Data)

• Provide Access to Packet Switched Network(Data)

• Doesn't Use Specific Protocol eg Q.931(L1,L2 and L3 of OSI-RM Context is used)

ISDN : Channels

• B channels : bearer channels(64Kbps)

– Carry information

• D channel :Delta channel(16Kbps)

– Used for signaling purposes

– Entire bandwidth is not used for signaling purpose

– Excess of 9.6 Kbps is available for packet switched data transmission applications

– Climate control, security alarm system etc.

ISDN : Devices

• NT1/NT2-4 wire conventional wiring connecting 2 wire local loop.

• TA- Terminal adapter connects TE2 devices to ISDN.

• TE1-Terminal Equipment 1, Specialized ISDN devices.

• TE2- Non ISDN Devices.

ISDN : Services

• One is known as the Basic Rate Interface or BRI

– Used in homes.

• The other is known as the Primary Rate Interface or PRI

– Used in large businesses

ISDN: BRI Use of 2B+1D channel

NT 1

ISDN Terminal Adapter

Phone Computer

ISDN BRI Line

2B +D

Network Terminator

ISDN: PRI

• 23B+1D Channel

• Delivered over T1-1.544Mbps

• Aggregate speed of PRI from all 23 B channels and the single D Channel is computed as follows:

– 23 * 64 + 64 + xx = 1.544 Mbps

• A separate DSU/CSU converts digital data frames from the communications technology used on a local area network (LAN) into frames appropriate to a wide-area network (WAN) and vice versa

ISDN : Pros and Cons

• Cons: – Not "always-on". – Expensive, considering its speed. – Generally requires on-site installation by an engineer. – Intermittent connections, Requires additional

hardware, new wiring, Difficult to get installed, Limited availability etc

• Pros – Signaling – Speed. – Multiple access

Refrences

• Amit Shah and D.Ramakrishnan, FDDI: A HIGH SPEED NETWORK, PTR PRENTICE HALL, 1994

• Cisco:Networking Basics.

• Wikipedia.org

• HTTP://WWW.CISCO.COM/UNIVERCD/CC/TD/DOC/CISINTWK/ITO_DOC/FDDI.HTM#XTOCID14

• http://www.pacbell.com/products/business/fastrak/networking/isdn/info/isdn-guide

• http://www.adtran.com/support/isu/mpfaq.html