adsl introduction v1.1

8/10/2019 Adsl Introduction v1.1

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A10&DSL D&T Group

VLAN & ADSL Introduction

V1.1

AM_BT02_E1_P3


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Course Outline

VLAN introduction

ADSL principle


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VLAN introduction

1. VLAN conception:

VLANVirtual LAN:

LAN can be the network which consist of few appliance

computers, also it can be certain corporation network which iscomposed of hundreds of computers.


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One VLAN is a broadcast domain

VLAN introduction


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Switch 1

Switch 2

Switch 3

Switch 4 Switch 5

A B

VLAN introduction

2. Why must create VLAN ?

If in the following network, computer A should communicate

computer B.


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Switch 1

Switch 2

Switch 3

Switch 4 Switch 5

ARP Request

Broadcast

Broadcast frame will betransferred to every

computer of this network,

and be the CPU burden of

every computer.

VLAN introduction


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VLAN introduction

In fact, the broadcast frame will often occur.

Lead to the waste of bandwidth and CPU.

VLAN: we can design VLAN structure at random.


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1 2 3 4Switch

Broadcast

frame

Switch received the

broadcast frame, then

only transferred to the

other ports which

belong to the same

VLAN.

Broadcast

area

Broadcast

frame

Broadcast

area

VLAN introduction

3. Realize VLAN mechanism

VLAN limits the range in which broadcast frame can be

transferred to divide the broadcast area.


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1 2 3 4switch

VLAN introduction


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VLAN introduction

4. How to communicate between different VLAN?

1) Access link

Access link is always belong to single VLAN, and only send

data frame to his belonging VLAN. In most case, access link islinkage with client station.

2) Trunk link

Trunk link also call Tagged Link, it is kind of port be able to

support multi different VLAN communication. The data frame

on the trunk link are enclosed an indicator to identify the frame

belongs to which VLAN.


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Access Links

VLAN introduction

An access link is a link that is a member of only one VLAN


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Trunk Link

VLAN introduction

A trunk link is capable of carrying multiple VLANs


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VLAN introduction

Specifically developed for multi-VLAN, inter-switchcommunications

Places a unique identifier in header of each frame

VLAN1

VLAN1

VLAN2VLAN2

VLAN3

VLAN3

Trunk link

VLAN1 VLAN2 VLAN3

Access link


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VLAN introduction

3) Access Ports

An Access port can only belong to one VLAN

4) Trunk Ports

Trunk ports carry data belonging to several VLANs

Trunk ports use tagging to identify which VLAN a packet is

associated with Trunk ports are IEEE 802.1q compliant

The purpose of Trunk Ports is to span a VLAN across several

devices (DSLAM, Switch or Router)


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Access Ports Green VLAN Access Ports Green VLAN

Access Ports

Red VLAN

Access Ports

Red VLAN

Access Ports

Blue VLANAccess Ports

Blue VLAN

Trunk Port

RS1 RS2

VLAN introduction


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VLAN introduction

5. IEEE802.1Q protocol:

Dot One Q, one protocol to add identification information for

the data frames.

Based on IEEE802.1Q, the adding information just like tag, soits also been called as Tagging VLAN.


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Ethernet Version 2

6Bytes 6Bytes 2Bytes 461500Bytes 4Bytes

Destination MAC

address

Source MAC

address

CRCdataType

Destination MAC

address

Source MAC

address

CRCdataTPID TCI Type

6Bytes 6Bytes 2Bytes 461500Bytes 4Bytes

IEEE802.1Q

0x8100

2Bytes 2Bytes

Including 12bit

VLAN identifier

CRC is been count

again.

VLAN introduction


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VLAN introduction

6. Tagged configuration principle

For SNI, trunk link should be configured as tagged;

For UNI, the port directly connecting to computer ( terminal)should be configured as untagged.


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Course Outline

VLAN introduction

ADSL principle


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Copper Cable

Office

Subscribers

PSTN

Optic

Fiber

Switching Module Wiring rack

Voice Service


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Copper Cable

Office

SubscribersPSTN

Optic

Fiber

Switching Module Wiring rack

1By common Modem: 56kbit/s

2By ISDN: 128kbit/s

Narrowband Internet Access Mode


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ATM/IP

Copper

Cable

Subscriber

PSTN

Office

10BaseTATU-R

Splitter

A

D

L

MSAN

I

C

S

A

D

L

Switching

ModuleMDF

A

L

C

ADSL principle


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ADSL principle

what is ADSL?

ADSLAsymmetric Digital Subscriber Line

Features:

1. ADSL is a type of accessing technology.

2. It is possible to transmit both voice and high-speed data signalswithout affecting one another,

3. Different frequencies are assigned to voice and high-speed datasignals:

Voice

0-4KHz Data

uplink 30KHz--138KHzdownlink 138KHz--1.1MHz

4. Data Signal Rate: max. downlink rate: 8Mbps, max. uplink rate:1Mbps, max. transmit distance: 4.5~5km


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ADSL principle

ADSL Channel Frequency A l locat ion (Frequenc y-division

mult ip lexing )

POTS Uplink channel Downlink channel

POTS

4kHz 30kHz 138kHz

4kHz 30kHz 138kHz

1.104MHz

1.104MHz

FDM

b

ordinary call signals : 04kHz

uplink signals : 30138kHz

downlink signals: 1381104kHz


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G.DMT Discrete Multi-Tone

Figure shows the G.DMT spectrum with indication of the POTS,upstream pilot tone, downstream pilot tone, subcarrier spacing, andnumber of subcarriers for the upstream and downstream direction.The underlying modulation technique is based on QAM.


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ADSL principle

Interleave channelAdd an interleaving process to solve

burst out defects by dispersing the wrong sub-channels, and

then recalculating and rearranging channels to increase their

anti-defect ability. They are long waiting time and high

reliability channels for data transmission.

Fast-only channelShort waiting time, fast speed and low

reliability channel without interleaving process. It is fit for

transmitting video and voice data of high real time and low

reliability requirement.


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ADSL principle

The ADSL transmission rate, especially downlink rate,depends on the line distanceabsolutely.

Factors affect line transmission quality: line distance, cablespecifications, with/without bridge connector and interferenceon the line.

Line attenuation is in active rate with line distance andfrequency, and is in negative rate with cable diameter, so that,when talk about ADSL performance, the cable specificationsand line distance must be instructed.

Commonly, within 2 km, line distance does small influenceupon ADSL transmission rate. But over 2 km, ADSLtransmission rate will drop rapidly while line distance increases.


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DSL Network

High-level ArchitectureCustomer Premises

Network Service Provider

SHDSL

VDSL

ADSLData

Data

Data

POTS

SHDSL

VDSL

ADSL Data

Data

Data

S

YMMETRIC

ASYMM

ETRIC

SHDSL(Single-Pair High Bit Rate DSL)One wire pair Symmetric transmission

Data rates variable rates of 192 kbps ~ 2.312 Mbps

Distance up to 5.5 km

VDSL(Very High Data Rate DSL)One wire pair Eight variable line rates operating distances

Autorate plug-n-play configuration Data rates up to 13/52 Mbps


ADSL(Asymmetric DSL)One wire pair Asymmetric transmission

Data rates from 1.5Mbps/64kbps to 8Mbps/1024kbps with POTS


DSL COMPARISON


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adsl introduction v1.1

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