lec21 22 isdn lecture

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BROADBAND DIGITAL NETWORKSBy Engr. Awais Ahmed Khowaja

Mehran University of Engineering and Technology, Jamshoro.

01TL-BATCHThis class will meet: 8.00-10.00 a.m. (Mondays)

10.00-12.00 noon (Tuesdays)

Today's Lecture:ISDN

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Asynchronous Versus ISDN

• Analog converted to digital and back

Channelbank

Channelbank

SWSW SWSW

• Digital end-to-end

Channelbank

Channelbank

SWSW SWSW

The advantages of ISDN over analog connections include:

Higher speedFaster call setupCheaper than leased linesVoice and data can be run simultaneously

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ISDN Services and Channelized E1 and T1

56/64 kbps56/64 kbps

16 kbps

144 kbps

2B

D }{BRI

T1 1.544 Mbps

or

E1 2.048 Mbps (includes sync)

23B (T1) or30B (E1)

D

64 kbpseach

64 kbps}PRI

2.048 Mbps(includes sync)

31 64 kbpschannels }E1

1.544 Mbps(includes sync)

24DS0s }T1

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BRI Call Processing

ISDNservice provider

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B channel

D channel/SS7 signaling

2 SS7

Q.931 signaling Q.931 signaling

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TE1 NT1 LE

Local loop terminator

ISDN local exchange

ISDN terminal equipment

NT2

Customer premises switching equipment

TE2 TA

Non-ISDN terminal

equipment

Terminal adapter

S U

R

T

BRI Functional Groups and Reference Points

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Physical Representation of BRI Reference Points

Cisco ISDNrouter

To ISDNservice

Walljack

4-wirecircuit

2-wirecircuit

S/T UTA NT1NT1

S/T bus

S/T bus

S/T interface as a multipoint connection

To non-ISDNdevice (TE2)

R

ISDNphone

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PRI—Layer 1 Standards and Reference Points

LE

U

ITU-T I.431ANSI

T1.601

TE CSU/DSU

S/T

ITU-TI.430

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ISDN Protocol Layers

Layer 3

LAPD (Q.921)

D Channel B Channel

I.430/I.431/ANSI T1.601I.430/I.431/ANSI T1.601

HDLC/PPP/FR/LAPB

Layer 1

Layer 2

DSS1 (Q.931) IP/IPX

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ISDN

NT1

Daisy-chainS/T bus

TEI/SAPI

TEI/SAPI LE

ISDN Layer 2

–ITU-T Q.920 and Q.921–Defines logical link between TE/TA and NT2/LE–Carries Layer 3 D-channel messages

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ISDN Layer 3—D Channel Q.931

• Q.931 defines call control between the TE and local switch

TE ETNT1 LTQ.931

ISDN switch (LE)

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Q.931 Messaging—Call Setup Example

Callingparty

Calledparty

Setup

Connect acknowledge Connect

acknowledge

Setup

Setup acknowledge

Call proceeding

Alerting

Connect

Alerting

Connect

Call proceeding

Tim

e

ISDN service provider

ISDNswitch

ISDNswitch

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Q.931 Messaging—Call Teardown Example

Released

Disconnect

Calling party Called partyDisconnect

Released

Release complete

Release complete

Release

Tim

e

ISDN service provider

ISDNswitch

ISDNswitch

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DDR Operation

Interesting?

Connected?

Phone #?

Connected?

Dial

No

Yes

Yes

No

No

Send

Incoming packet

ResetIdle

TimerYes

NoInterface

up?

Yes

Yes

No

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Using DDR with ISDN

ISDN service provider

BRI or

PRI

1.

2. Remoterouter

1. Packet arrives2. Switch packet to DDR interface, determine if interesting 3. If interesting, dial DDR destination via ISDN 4. Connect to remote router

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4.

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ISDN Configuration Tasks

–Global configuration–Select switch type–Specify traffic to trigger DDR call

–Interface configuration–Select interface specifications–Configure ISDN addressing

–Optional feature configuration

ISDN

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ISDN Configuration Commands

–Set global parameters with this command:• isdn switch-type

–Set interface parameters with these commands:• encapsulation ppp

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Router(config)#isdn switch-type switch-typeRouter(config)#isdn switch-type switch-type

Router(config-if)#isdn switch-type switch-typeRouter(config-if)#isdn switch-type switch-type

Selecting the ISDN Switch Type

–Specifies the type of ISDN switch with which the router communicates

–Global or interface command

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Setting Interface Protocols

Router(config-if)#encapsulation {ppp | hdlc}Router(config-if)#encapsulation {ppp | hdlc}

• Selects framing for that ISDN BRI

Router(config-if)#ppp authentication {pap | chap | ms-chap}

Router(config-if)#ppp authentication {pap | chap | ms-chap}

• Selects PPP authentication type

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DDR Configuration Tasks

1. Define interesting traffic2. Assign interesting traffic definition

to ISDN interface 3. Define destination 4. Define call parameters

ISDNserviceprovider

BRI or

PRIRemoterouter

Interesting traffic arrives

Dial destination

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Defining Interesting Traffic

Router(config)#dialer-list dialer-group-numberprotocol protocol-name {permit | deny} list access-list-number

Router(config)#dialer-list dialer-group-numberprotocol protocol-name {permit | deny} list access-list-number

• Defines interesting packets for DDR • Associated with the dialer group assigned to the interface

Router(config-if)#dialer-group group-number Router(config-if)#dialer-group group-number

• Assigns an interface to the dialer access group specified in the dialer-list command

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