HCNA(HCDA) Huawei Certified Network Associate Training.pdf

HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential 1

The privilege of HCNA/HCNP/HCIE: With any Huawei Career Certification, you have the privilege on http://learning.huawei.com/en to enjoy:

1Comprehensive E-Learning Courses

ContentAll Huawei Career Certification E-Learning courses

Methods to get the E-learning privilege : submit Huawei Account and email being used for Huawei Account

registration to [email protected] .

2 Training Material Download

Content: Huawei product training material and Huawei career certification training material

MethodLogon http://learning.huawei.com/en and enter HuaWei Training/Classroom Training ,then you can

download training material in the specific training introduction page.

3 Priority to participate in Huawei Online Open Class(LVC)

ContentThe Huawei career certification training covering all ICT technical domains like R&S, UC&C, Security,

Storage and so on, which are conducted by Huawei professional instructors

MethodThe plan and participate method please refer to LVC Open Courses Schedule

4Learning Tool: eNSP

eNSP (Enterprise Network Simulation Platform) is a graphical network simulation tool which is developed by

Huawei and free of charge. eNSP mainly simulates enterprise routers, switches as close to the real hardware as

it possible, which makes the lab practice available and easy without any real device.

In addition, Huawei has built up Huawei Technical Forum which allows candidates to discuss technical issues with

Huawei experts , share exam experiences with others or be acquainted with Huawei Products(

http://support.huawei.com/ecommunity/

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Huawei Certification

HCDA-HNTD

Huawei Networking Technology and Device

Huawei Technologies Co.,Ltd

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Copyright Huawei Technologies Co., Ltd. 2012. All rights reserved.

No part of this document may be reproduced or

transmitted in any form or by any means without prior written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions

and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd. All other trademarks and trade names

mentioned in this document are the property of their respective holders.

Notice

The information in this document is subject to change without notice. Every effort has been made in the preparation

of this document to ensure accuracy of the contents, but all

statements, information, and recommendations in this document do not constitute the warranty of any kind, express

or implied.

Huawei Certification

HCDA-HNTD Huawei Networking Technology and

Device

Edition 1.6

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Huawei Certification System

8KRG_OTM UT OZY YZXUTM ZKINTOIGR GTJ VXULKYYOUTGR ZXGOTOTM Y_YZKSGIIUXJOTM ZU JOLLKXKTZ I[YZUSKXY GZ JOLLKXKTZ RK\KRY UL /): ZKINTURUM_.[G]KO IKXZOLOIGZOUT OY IUSSOZZKJ ZU VXU\OJK I[YZUSY ]OZN G[ZNKTZOIVXULKYYOUTGRIKXZOLOIGZOUT

(GYKJ UT INGXGIZKXOYZOIY UL /): ZKINTURUMOKY GTJ I[YZUSKXYTKKJY GZJOLLKXKTZ RK\KRY .[G]KO IKXZOLOIGZOUT VXU\OJKY I[YZUSKXY ]OZNIKXZOLOIGZOUTY_YZKSULLU[XRK\KRY

.)*' .[G]KO )KXZOLOIGZOUT *GZGIUS 'YYUIOGZK OY VXOSGX_ LUX /6TKZ]UXQSGOTZKTGTIKKTMOTKKXYGTJGT_UZNKXY]NU]GTZZURKGXTZNK/6TKZ]UXQQTU]RKJMK.)*'IKXZOLOIGZOUTIU\KXYZNK:)6/6HGYOIYXU[ZOTMY]OZINOTM GTJ UZNKX IUSSUT LU[TJGZOUTGR QTU]RKJMK UL /6 TKZ]UXQYZUMKZNKX ]OZN .[G]KO IUSS[TOIGZOUTY VXUJ[IZY \KXYGZORK XU[ZOTMVRGZLUXS

HC

IE-

R&S

UC&

C VC

Cl

oud

Stor

age

Wire

less

Tra

nsm

issi

on S

ecur

ity

ICT

Car

eer C

ertif

icat

ion

Expert

HCN

A-

Desi

gn

HCN

P-

Desi

gn

HCN

A(HC

DA)

HCAr

HCN

A-W

LAN

HC

NA-

U

C HC

NA-

VC

HC

NA-

Clou

d HC

NA-

LT

E HC

NA-

Tr

ansm

issi

on

HCN

A-Se

curit

y HC

NA-

CC

HCN

P-Ca

rrie

r (H

CDP-

Carr

ier)

HC

NP-

WLA

N

HCN

P-

UC

HCN

P-

VC

HCN

P-

Clou

d HC

NP-

LT

E HC

NP-

Tran

smis

sion

HC

NP-

R&S

(HCD

P)

HCN

P-

Secu

rity

HCN

P-St

orag

e HC

NP-

CC

HCN

A-St

orag

e

H

Associate

Professional

HCIE

- De

sign

Prop

osed

Adv

ance

d re

latio

nshi

p N

eces

sary

adv

ance

d re

latio

nshi

p

HC

IE-

Carr

ier

HCIE

- LT

E HC

IE-

WLA

N

HCIE

-Se

curit

y

HCIE

-Tr

ansm

issi

on

HCIE

- CC

HC

IE-

UC

HCIE

- Cl

oud

HCIE

- VC

HC

IE-

Stor

age

Architect

Rout

ing

& S

witc

hing

W

LAN

IC

T Co

nver

genc

e De

sign

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

,UXK]UXJ

5[ZROTK

:NOY HUUQ OY GHU[Z ZNK .[G]KO IKXZOLOKJ *GZGIUS 'YYUIOGZK IKXZOLOIGZOUT:NK

YZ[JKTZY]NU]GTZZUVXKVGXKLUXZNK.)*'K^GSUX]GTZZURKGXTZNKZKINTURUM_

GHU[Z:)6/6VXUZUIURYZGIQYXU[ZKXY]OZIN='4+ZNKXTKZGTJNU]ZUIUTLOM[XK[YK

UTZNK

OSVRKSKTZGZOUTYUTZNK

_

Icons Used in This Book

IPv6 Router SOHO Router Voice Router Low-end Router

Core Router Hub Convergence Switch Core Switch

Edge Switch Cascade Switch AP AP Amplifier Wireless Bridge

Wireless Network Card Access Server Audio Gateway Firewall Internet Telephony

Socket switch

High-end Router

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

HCDA-HNTD

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Table of Contents Module 1 Network Fundamentals .................................................................................Page 1

IP Network Fundamental ...............................................................................................Page 3

TCPIP Basis...........................................................................................................................Page 43

IP Addressing and Routing ...........................................................................................Page 86

Protocols of Transprot Layer.........................................................................................Page 127

Introduction to Common Application........................................................................Page 148

Module 2 Routing ................................................................................................................Page 163

VRP Basis and Operation ...............................................................................................Page 165

Routing Protocol Basis.....................................................................................................Page 202

Static Route .........................................................................................................................Page 230

Dynamic Routing Protocol Basis...................................................................................Page 248

Distance-vector Routing Protocol ...............................................................................Page 260

RIP Routing Protocol.........................................................................................................Page 283

RIP Troubleshooting..........................................................................................................Page 311

OSPF Routing Protocol Basis..........................................................................................Page 342

Module 3 Switching ..............................................................................................................Page 375

Ethernet Overview .............................................................................................................Page 377

Principle of Ethernet Device ...........................................................................................Page 395

Ethernet Port Technology ................................................................................................Page 422

VLAN Technology Principle and Configuration.........................................................Page 449

VLAN Routing .......................................................................................................................Page 470

STP Principle and Configuration.....................................................................................Page 489

VRRP Principle and Configuration..................................................................................Page 522

Page1

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Module 4 WAN ........................................................................................................................Page 545

HDLC Principle and Configuration.................................................................................Page 547

PPP Principle and Configuration ....................................................................................Page 563

FR Principle and Configuration........................................................................................Page 697

Module 5 Network Security-Firewall Product Basis .....................................................Page 631

Firewall Product Basis .........................................................................................................Page 633

USG Basic Function and Configuration ........................................................................Page 655

Module 6 Product.....................................................................................................................Page 695

Huawei NE40E-X Series Router Introduction..............................................................Page 697

AR G3 & Sx7 Brief ...............................................................................................................Page 726

Page2

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Module 1 Network Fundamentals

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Data refers to information in any format. The format used to encode any information must follow agreed or standard rules before successful communication between a sender and receiver is possible.

For example, a picture can be broken down into a number of dots referred to as pixels, each pixel can then be represented by a number which can then be encoded ready for transmission. The format used to encode the image data by the sender must be understood by the receiver to enable them to decode and rebuild the picture.

Common types of data that can be encoded for transmission include text, numbers, pictures, audio, and video. many standard ways of encoding the different types of data exist.

Data communication is the process of exchanging data between two devices through a transmission medium, such as a wired or wireless network.

Page7

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

A simple data communication system consists of a message, a sender, a receiver, a (transfer) medium, and a protocol.

Message:

A message contains information that needs to be communicated. This could be text, numbers, a picture, sound, or video which will be encoded and transmitted as one or more messages.

Sender:

The sender is a device or system that transmits the message, this could be a PC, a workstation, a server, or a mobile phone.

Receiver:

The receiver is a device or system that receives the message, this could be a PC, a workstation, a server, a mobile phone, or a television.

Medium:

The medium is a physical or logical connection between the sender and the receiver which is capable of carrying the message. Typical types of medium are twisted pair cable, coaxial cable, optical fiber and radio wave.

Protocol:

Page8

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The protocol is the set of rules that controls the way in which data exchanged. The protocol does not necessarily define what the original data is or how it is encoded, just how it should be exchanged by two communicating devices. Protocol rules define such things as the speed at which data is transferred and the size of the data unit that is sent. It will also define when a communication session starts and ends. These rules can be likened to the rules which define the way we talk to each other or read and write, without such rules even if we use the same language we cannot communicate.

Page9

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

There are three different ways in which two devices can communicate in data networking:

Simplex communication:

Simplex communication is in one direction. One device can only send messages, the other one can only receive messages.

For example a keyboard is a device which only sends data and a monitor a device that can only receive data both use simplex communication.

Half-duplex communication:

Half-duplex communication is two way but only one device can be sending at any time, the other must be receiving. Both devices are capable of sending and receiving but communication can only be in one direction at a time.Two-way radios, such as those used by police and taxis work in half-duplex mode.

Full-duplex communication:

Full-duplex communication is two way concurrently, both devices can send and receive messages at the same time.A motorway is full duplex as traffic is able to travel in both directions at the same time .Telephony networks are also full duplex, however most humans can only either talk orlisten - not do both at the same time.

Page10

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

A network is any group of people, things or places that are interconnected in some way. Networks exist everywhere in our life, we have road, rail, telephone and postal networks which we use on a daily basis.

A computer network consists of two or more computers and peripheral which are interconnected by communication lines.The computers in a network can easily exchange and share information and resources .

Computer networks were developed to meet increasing requirements for exchanging information and sharing resources.

In early computer networks , each computer was an independent device, there was little or no communication between systems.

As computer and communication technologies evolved, communication between different systems was made possible.

Standard protocols understood by different systems made sharing resources and data possible and improved resource utilisation.

Page12

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

In recent years, the computer network is developing rapidly. The computer communications network and the Internet have become the basic part of the society. The computer network is applied to many fields of industry and commerce, including e-bank, e-commerce, modernized enterprise management,and information service. From remote education to government routines, and to todays e-community without the network technology they can not work. The saying "network exists everywhere in the world" is not an exaggerated statement. The computer network came into being in 1960s. At that time, the network was a host-based low-speed serial connection providing program running, remote printing, and data service. The System Network Architecture (SNA) of IBM and X.25 public data network are such kind of network. In 1960s, the defense department of US funded a packet switching network called ARPANET, which was the earliest rudiment of the Internet. In 1970s, the commercial computing mode, which featured personal computers,came forth. Initially, personal computers were used as independent devices. Because of the complexity of commercial computing, many terminal devices needed to cooperate, and thus the local area network (LAN) was developed. The LAN reduced the expense on printers and disks dramatically.

Page13

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

In 1980s and 1990s, in order to deal with the increasing demand on remote computing,the computer industry developed many wide area network protocols (including TCP/IP and IPX/SPX). Then the Internet was expanded fast. Nowadays TCP/IP is extensively used on the Internet.

Page14

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The topology defines the organization of devices in a network. A LAN can adopt various topologies, such as the bus topology and star topology.

In the bus topology, all devices are connected to a linear network media, which is called the bus. When a node transmits data in a network adopting the bus topology, the data reaches all nodes. Each node checks the data. If the data is not sent to this node, the node discards the data. If the data is sent to this node,the node accepts the data and transfers the data to the upper layer protocol. A typical bus topology has simple layout of lines. Such layout uses short network media, and thus, the expense on cables is low. However, this topology makes it difficult to diagnose and isolate faults. Once a fault occurs, the entire network will be affected. In addition, each device in the LAN sends data to all the other devices, which consumes large amount of bandwidth. It will lower network performance.

In the star topology, devices are connected to a central control point. A device communicates with another device through the point-to-point connection between it and the hub or switch. The start topology is easy to design and install, because network media connect the hub or switch and workstations. The star topology is easy to maintain, because the network can be easily

Page15

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

modified and network faults can be easily be located. The star topology is extensively used in LAN construction. Of course the star topology has its weakness. Once the central control device becomes faulty, the single point failure may be occur. In addition, a Network media can connect only one device, so large amount of network media are needed and the LAN installation cost increases.

These topologies are logical structures and are not necessarily related to the physical structure of devices. For example, logical bus and ring topologies usually adopt the physical star structure. A WAN usually adopts the star, tree, fullmeshed, or half-meshed topology.

Page16

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The Internet is a large network formed by networks and devices. Based on the covered geographic scope, networks are classified into LAN, WAN, and Metropolitan Area Network (MAN) whose size is between the LAN and WAN.

Local Area Network (LAN)

A LAN is formed by connected communication devices in a small area. A LAN covers a room, a building, or an industry garden. A LAN covers several kilometers. It is a combination of computers, printers, modems, and other devices interconnected through various media within several kilometers.

Wide Area Network (WAN)

A WAN covers a larger geographic scope, such as a state or a continent. It provides the data communication service in a large area and is used to connect LANs. The China Packet Network (CHINAPAC), China Data Digital Network (CHINADDN), China Education and Research network (CERnet), CHINANET, and China Next Generation Internet (CNGI) are all WANs. A WAN connects LANs that are far from each other.

Page17

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

A LAN is formed by interconnected communication devices in a small area, such as a room, a building, and a campus. In general, a LAN covers several kilometers. The LAN is featured by short distance, low delay, high data transmission speed, and high reliability. Common LANs are Ethernet and Asynchronous Transfer Mode (ATM). They are different in topology, transmission speed, and data format.Ethernet is the most widely used LAN. The following network devices are used in LAN construction: Cables: A LAN is extended by cables. Various cables are used in LANs, for example, the fiber, twisted pair, and coaxial cable. Network Interface Card (NIC): An NIC is inserted in the main board slot of a computer. It transforms the data to the format that other network devices can identify and transmits the data through the network media. Hub: A hub is a shared device that provides many network interfaces to connect computers in the network. The hub is called a shared device because all its interfaces share a bus. At the same time, only one user can transmit data, and so the data amount and speed of each user (interface) depends on the number of active users (interfaces). Switch: also called a switched hub. A switch also provides many interfaces to connect network nodes but its performance is much higher than that of a shared hub. It can be considered to have many buses so that devices connected to each interface can independently transmit data without affecting other devices. For

Page18

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

users,the interfaces are independent of each other and have fixed bandwidth. In addition, a switch has some functions that a hub lacks, such as data filtering,network segmentation, and broadcast control. Router: A router is a computer device used to connect networks. A router works at the third layer (network layer) of the OSI model and is used to route, store, and forward packets between networks. Generally, a router supports two or more network protocols so that it can connect different type of networks A router can also run dynamic routing protocols to dynamically route packets.

Page19

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

A WAN covers a larger geographic scope, such as a state or a continent. The China Packet Network (CHINAPAC), China Data Digital Network (CHINADDN),China Education and Research network (CERnet), CHINANET, and abuilding China Next Generation Internet (CNGI) are all WANs. A WAN connects LANs that are far from each other. It consists of the end system(users on two ends) and the communication system (the link between two ends). The communication system is the key of the WAN and it falls into the following types: Integrated Service Digital Network (ISDN): a dial-up connection mode. The ISDN BRI provides 2B+D data channels. Each B channel provides the speed of 64 kbit/s and the highest speed can be 128 kbit/s. The ISDN PRI has two standards: the European standard (30B+D) and the North America standard (23B+D). The ISDN uses the data transmission mode, which features fast connection and high reliability. Two devices in the ISDN can identify the number of each other. The call cost of the ISND is higher than that of the ordinary telephony network, but the double-channel structure supports two independent lines. The ISND is applicable to individual subscribers or small offices. Leased Line: called DDN in China. It is a point-to-point connection that transmits data at the speed of 64 kbit/s to 2.048 Mbit/s. The leased line guarantees data transmission and provides constant bandwidth, but the cost is high and the point to-point structure is not very flexible.

Page20

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

X.25: a WAN type that appeared early and is still in extensive use at present. It transmits data at the speed of 9600 bit/s to 2 Mbit/s. X.25 adopts the redundant mode and is fault tolerant, so it features high reliability. But the transmission speed is low and the delay is high. Frame Relay: a comparatively newer technology developed on the basis of X.25. The transmission speed is between 64 kbit/s and 2.048 Mbit/s. The Frame Relay is flexible. It implements point-to-multipoint connection. In addition, FR can transmit data at a speed that exceeds the Committed Information Rate (CIR) when large amount of data needs to be transmitted, and it allows certain burst traffic. For these reasons, FR is a good choice for business subscribers. Asynchronous Transfer Mode (ATM): a cell exchange network that features high speed, low delay, and guaranteed transmission quality. Most of ATM network use fibers as the connection medium. The fiber provides a high speed of over 1gigabit, but the cost is also high. ATM is also a WAN protocol.

Page21

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The WAN operates in a scope larger than that of the LAN. In the WAN, the network access is implemented through various serial connections. Generally, enterprise networks are connected to the local ISP through the WAN lines. The WAN provides fulltime and part-time connections. In the WAN, serial interfaces can work at different speeds.

The following devices are used in the WAN:

Router: In the WAN, messages are sent to the destination according to the address. The process of looking for the transmission path is called routing. A router will send data to the destination by establishing routes between WANs and LANS according to their address information.

Modem: As the device used to transform signals between the end system and communication system, a modem is the indispensable device in a WAN. Modems are classified into synchronous modem and asynchronous modem. The synchronous modem is connected to the synchronous serial interface and is applied to the leased line, Frame Relay, and X.25. The asynchronous modem is connected to the asynchronous serial interface and is applied to the PSTN.

Page22

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

ARPAnet solves the problem of network robustness. That is, once a device fault or link fault occurs, data transmission must be ensured between any two nodes if the two nodes are physically connected. For the high ability of self-healing,ARPAnet meets the requirement in wars. It comes of the Defence Advanced Research Projects Agency (DARPA).

In 1985, the National Science Foundation (NSF) established the NSFnet. NSF established a WAN consisting of regional networks and connected these regional networks to the super computer center. In June 1990, the NFSnet took the place of the ARPAnet and became the backbone network of the Internet. Owing to the NSFnet, the Internet is open to the public, while it was only used by computer science researchers and governments before.

The second leap of the Internet was attributed to the commercialization in early of the 1990s. As soon as commercial organizations entered the world of Internet, they found the great potential of Internet in communications, information searching, and customer service. Then numerous enterprises in the world swarmed into the Internet, which resulted in a new leap of the Internet. In 1995, NSFnet came to an end and it was replaced by a new Internet backbone network operated by multiple private companies.

Page23

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Currently, the Internet is not a simple hierarchy, instead, it is formed by many WANs and LANs connected by connecting devices and exchange devices. End users are connected to the Internet through the service provided by Internet service providers (ISPs). ISPs are classified into international service providers, national service providers, regional ISPs, and local ISPs. International service provider An international service provider connects networks of different countries. National service provider (NSP) A national service provider operates on backbone networks that are built and maintained by professional companies. These backbone networks are connected by complicated switching devices (usually operated by the third party) so that end users can be connected to the backbone network. The switching devices are called network access points (NAPs). NAPs transmit data at a high speed. Regional ISP A regional ISP is a small ISP connected to one or more NSPs. Regional ISPs transmit data at a lower speed. Local ISP A local ISP provides service for end users. A local ISP is connected to a regional ISP or an NSP. Most end users are connected to local ISPs.

Page24

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

NAP An NAP connects backbone networks. It is usually a complicated switching workstation operated by the third party.

Page25

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

A network protocol is a set of formats and conventions stipulated and observed by communication parties so that devices in different computer networks can communicate. A network protocol is the standardized description of a series of rules and conventions. It defines how network devices exchange information.Network protocols are basis of the computer network. Only the devices that comply with related network protocols (laws for interconnected devices in the network) can communicate with each other. Any device that does not comply with the network protocol cannot communicate with other devices.

What is a protocol? Take the telegraph for example. Before sending a telegraph,the two parties must define the transmission format of the telegraph, for example,what signal indicates the start, what signal indicates the end, how to handle errors,and how to express the name and address of the sender. The predefined format and convention is a protocol.

Network protocols include the Transfer Control Protocol/Internet Protocol (TCP/IP), Internetwork Packet eXchange/Sequenced Packet eXchange (Novell IPX/SPX), and IBM System Network Architecture (SNA). The most widely used protocol is the TCP/IP stack, which has become the standard protocol of the Internet.

Page27

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

A standard is a set of rules and processes that are widely used or defined by the government. A standard describes stipulations in a protocol and sets the simplest performance set for guaranteeing network communications. IEEE 802.X is the dominant LAN standard.

Page28

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Many international standardization organizations made great contributions to development of the computer network. They unify network standards so that devices of different vendors can communicate with each other. Till now, the following standardization organizations have made contributions to development of the computer network.

International Organization for Standardization (ISO)

ISO stipulates standards for large-scale networks, including the Internet. The ISP brings forward the OSI model that describes the working mechanism of network.

The OSI model is a comprehensible and clear hierarchical model of the computer network.

Institute of Electrical and Electronics (IEEE)

IEEE defines standards for network hardware so that hardware devices of different vendors can communicate with each other. The IEEE LAN standard is the dominant standard for LANs. IEEE defines the 802.X protocol suite. 802.3 is the standard for the Ethernet; 802.4 is the standard for the token bus network;802.5 is the standard for token ring; 802.11 the standard fro the wireless local

Page29

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

area network (WLAN).

American National Standards Institute (ANSI)

ANSI is an organization formed by companies, governments, and other members voluntarily. The ANSI defines the standard for the fiber distribution data interface.

Electronic Industries Association/Telecomm Industries Association (EIA/TIA) They define the standards for network cables, for example, RS232, CAT5, HSSI,and V.24. They also define the standard for cabling, for example, EIA/TIA 568B.

International Telecomm Union (ITU)

They define the standard for the telecom network working as the WAN, for example, X.25 and Frame Relay.

Internet Engineering Task Force (IETF)

Founded at the end of 1985, the IETF is responsible for researching and establishing technical specifications related to the Internet. Now IETF has become the most authoritative research institute in the global Internet field.

Page30

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

IETF produces two types of files: Internet drafts and RFCs.

RFCs, which are used as standards, fall into the following types:

Proposals, namely, the recommended solutions Accepted standards that are used by all users and cannot be changed Optimal practices, a kind of introduction IETF standards are called RFCs, which are a series of files published by IETF.

In the past, RFC stood for Request for Comments. Now RFC is only a name without any special meaning. Currently, RFCs are formal files. There are about 5000 RFC files. The first one is RFC 1 Host Software, which was published on April 7th, 1969.

Many Internet-related protocols, such as IP, OSPF, BGP, and MPLS, are defined by RFCs.

Page31

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

A typical IP network is comprised of a backbone network, Metropolitan Area Network (MAN) and Access Network. The backbone network commonly interconnects networks from different countries and cities. Metropolitan Area Networks are located between the backbone network and the access network, and it is commonly comprised of a backbone layer, convergence layer and access layer. Access networks are used for terminal user access, it is usually in the layer2 access network, which is under the service access point. Users can access the internet via xDSL, Ethernet and so on.

The target network structure of IP MAN is divided into:

IP MAN Service access point (BRAS and service router) and the upper layer routers that compose the layer3 network.

IP MAN is comprised of a backbone layer, convergence layer and access layer.

Broadband access network The layer2 access network, which is under the service access point.

The network structure is divided into the layer2 convergence network and the last mile access network.

Page33

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

On the service plane, the structure can be divided into a public access network plane and the major account access network plane.

Page34

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The Metropolitan Area Network (MAN) is located between the backbone network and the access network, and interlinks different areas of a city.

The MAN provides the following services:

Internet access There are two access modes: dialup access mode and private line access mode.

In the dialup access mode, subscribers have different service attributes. In the private line access mode, subscribers in the same group have the same service attributes. The Asymmetric Digital Subscriber Line (ADSL) and Local Area Network (LAN) technologies are widely used as Internet access services. Both technologies support dialup access and private line access modes.

Virtual private network (VPN)

In recent years, enterprises have increasing requirements for diversified services. As such, VPN technology has become more and more popular. VPN is a private network constructed within a public network infrastructure with the help of Internet service providers (ISPs) and network service providers (NSPs).

Based on the implementation layer, VPN can be classified into Layer 2 VPN (L2VPN), Layer 3 VPN (L3VPN) and the Virtual

Page35

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Private Dial Network (VPDN). The VPDN provides network access to mobile personnel in enterprises and small-sized ISPs using the dialup function of the public network and the access network.

Page36

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The common Internet access modes are ADSL, Ethernet, and leased line. Household users usually choose the ADSL access mode, residential users prefer the Ethernet access mode, and enterprise users select the leased line access mode. Normally, the access network uses Layer 2 devices, such as digital subscriber line access multiplexers (DSLAM) and Ethernet switches, to provide the access service for users. The access network does not perform any control on users and it simply sets up Layer 2 connections to transparently transmit user information to upper-layer devices. The access network refers to all devices at the access layer.

The access layer uses the broadband remote access server (BRAS) to manage users.

The convergence layer generally uses aggregation routers or Layer 3 switches. The convergence layer aggregates traffic from the BRAS into the MAN devices and forwards this traffic through routing functions.

The following shows the Internet access process:

A user sends an Internet access request. Layer 2 devices in the access network establish a Layer 2 connection and transparently transmit the request to the BRAS.

Page37

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The BRAS performs user identity authentication and authorization, and allocates IP addresses to the user.

The BRAS routes the user packets to devices at the convergence layer. The devices at the convergence layer forward the packets through routing functions, to allow the user to have access to the Internet.

Page38

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

VPN services are classified into L3VPN services, L2VPN services and VPDN services. Here, we talk about the most common L3VPN services. L3VPN has multiple types, such as Internet Protocol Security VPN (IPSec VPN), Ground Radar Equipment VPN (GRE VPN) and Border Gateway Protocol/Multiple protocol Label Switching VPN (BGP/MPLS VPN).

The BGP/MPLS VPN model has three parts: customer edge (CE), provider edge (PE) and provider (P).

CE: It is an edge device on the user network. A CE provides interfaces that are directly connected to the service provider (SP) network. It can be a router, switch or a host.

PE: It is an edge router provided by the SP. A PE device is directly connected to the CE. On the MPLS network, all VPN operations are performed in the PEs.

P: It is a backbone router on the SP network. A P device is not directly connected to the CE. The P device forwards MPLS data, and does not maintain VPN information.

As shown in the figure on this slide, enterprise private line users A, B and C can communicate with each other on the LAN by means of the BGP/MPLS VPN network.

Page39

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Generally, the performance of the backbone network can be evaluated using the following indicators:

High reliability Devices on the backbone network must be stable, which is critical to the stable operation of the entire network. Therefore, network architects should properly design the network architecture and develop reliable network backup policies to ensure strong network self-healing capabilities.

Flexibility and scalability

To meet future network services, the network must be seamlessly expanded and upgraded while minimally affecting the network architecture and devices.

Flat networking The number of network layers and hops should be minimized to facilitate network management.

Proper planning of quality of service (QoS) In, the IP network also supports voice over IP (VoIP), video and key customer services. These services have high requirements on service in addition to carrying Internet access service quality. Therefore, support for QoS is network to the telecommunications network. To achieve support for QoS, QoS should be properly planned.

Operability and manageability Centralized monitoring,

Page40

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

rights-based management, and unified allocation of bandwidth resources are supported, which make the entire network controllable. one of the necessary conditions for the transition of the IP.

Page41

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Hierarchical plane structure

The hierarchical plane structure is commonly applied in the early-stage backbone network. Currently, most carriers in China use this structure, which is divided into three layers, core backbone layer, core convergence layer and core access layer. The core backbone layer is divided by area. Areas are connected in full-mesh or partial-mesh mode to improve network robustness. The core convergence layer adopts dual homing networking. Devices at this layer are dual-uplinked to an area or two areas at the core backbone.

Hierarchical spatial plane structure

In the hierarchical spatial plane structure, the network is divided in layers and planes. Different planes carry different services. Normally, services on two different planes are independent from each other. When one plane fails, the other plane acts as a backup plane. When designing the network, architects usually design the plane as one that can carry all services. As a network requires carrying multiple services, the hierarchical plane network model stands out with its features of a clear structure, large backup capacity and high security.

Page42

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Since the 1960s, computer networks have undergone a dramatic

development. To take the leading position and have a larger share

in the communication market, manufacturers competed in

advertising their own network structures and standards which

included IBMs SNA, Novells IPX/SPX., Apples Apple Talk, DECs DECnet and TCP/IP, which remains the most widely used today.

These companies pushed software and hardware that use their

protocols to the market enthusiastically. All these efforts promoted

the fast development of network technology and the prosperity of

the market of network devices. However, the network became more

and more complicated due to lack of compatibility between the

various protocols.

To improve network compatibility, the International Organization for

Standardization (ISO) developed the Open System Interconnection

Reference Model (OSI RM) which soon became the model of

network communications. The ISO followed the following principles

when they designed the OSI reference model:

Page47

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

1. Each layer of the model has its own responsibilities which

should help it stand out as an independent layer.

2. To avoid function overlapping, there should be enough layers.

The OSI reference model has the following advantages:

1. It simplifies network related operations.

2. It provides compatibility and standard interfaces for systems

designed by different institutions.

3. It enables all manufactures to be able to produce compatible

network devices, which facilitates the standardization of networks.

4. It lays the complex concept of communications down into

simpler and smaller problems, which facilitates our

understanding and operations.

5. It separates the whole network into areas, which guarantees

changes in one area will not affect other areas and networks in

each area can be updated quickly and independently.

Page48

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The OSI reference model has seven layers. From bottom to top,

they are physical layer, data link layer, network layer, transport layer,

session layer, presentation layer and application layer.

The bottom three layers are usually called lower layer or the media

layer, which is responsible for transmitting data in the network.

Networking devices often work at lower layers and network

interconnection is achieved by the cooperation of software and

hardware. Layer 5 to layer 7 form the upper layer or the host layer.

The upper layer guarantees data is transmitted correctly, which is

achieved by software.

Page49HC Series

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The functions of each layer of the OSI Reference Model are listed

as follows:

Physical layer: providing a standardized interface to physical

transmission media including voltage, wire speed and pin-out of

cables.

Data link layer: combines bits into bytes and bytes into frames.

Provides access to media using MAC address and error detection.

Network layer: providing logical addresses for routers to decide

path.(path selection)

Transport layer: providing reliable or unreliable data transfer

services and error correction before retransmission.

Session layer: establishing, managing and terminating the

connections between the local and remote application. Service

requests and responds of application programs in different devices

form the communication of this layer RPC,NFS and SQL belong to

this layer.

Presentation layer: providing data encoding and translation. Make

sure that the data sent by the application layer of one system can

be understood by the application layer of another system.

Application layer: providing network services as the closest layer to users among the seven layers. Page50

HUAWEI TECHNOLOGIESPage50 HC Series

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Since the OSI reference model and protocols are comparatively

complicated, they do not spread widely. However, TCP/IP has been

widely accepted for its openness and simplicity. The TCP/IP stack

has already been the main stream protocols for the Internet.

The TCP/IP model also takes a layered structure. Each layer of the

model is independent from each other but they work together very

closely.

The difference between the TCP/IP model and the OSI reference

model is that the former groups the presentation layer and the

session layer have been merged into the application layer. So the

TCP/IP model has only five layers. From bottom to top, they are:

physical layer, data link layer, network layer, transport layer and

application layer.

Page51

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Each layer of the TCP/IP model corresponds to different protocols.

The TCP/IP protocol stack is a set of communication protocols. Its

name, the TCP/IP protocol suite, is named after two of its most

important protocols: the Transmission Control Protocol (TCP) and

the Internet Protocol (IP). The TCP/IP protocol stack ensures the

communication between network devices. It is a set of rules that

define how information is delivered in the network.

Page52

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Each layer of the TCP/IP model uses Protocol Data Unit (PDU) to

exchange information and enable communication between network

services. During encapsulation, each succeeding layer encapsulates

the PDU that it receives from the layer above. At each stage of the

process, a PDU has a different name to reflect its new appearance.

For example, the transport layer adds TCP header to the PDU from

the upper layer to generate the layer 4 PDU, which is called a

segment. Segments are then delivered to the network layer. They

become packets after the network layer adds the IP header into

those PDUs. The packets are transmitted to the data link layer,

where they are added data link layer headers to become frames.

Finally, those frames are encoded into bit stream to be transmitted

through network medium. This process in which data are delivered

following the protocol suite from the top to the bottom and are added

with headers and tails is called encapsulation.

Page53

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

After encapsulation, data is sent to the receiving device after

transmission. The receiving device will decode the data to extract

the original service data unit and decides how to pass the data to

an appropriate application program along the protocol stack. This

reverse process is called de-encapsulation. The corresponding

layers, or peers, of different devices communicates through

encapsulation and de-encapsulation.

As the figure above shows, Host A is communicating with Host B.

Host A delivers data transformed from an upper layer protocol to

the transport layer. The transport layer encapsulates the data

within the segment and send it to the network layer, which adds a

header. Then the segment is encapsulated within an IP packet,

which adds another header, called the IP header. Next, the IP

packet is sent to data link layer where it is encapsulated within a

frame header and trailer. The physical layer then transforms the

frame into bit stream and sends it to Host B through the physical

cable.

Page54

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

When Host B receives the bit stream, it sends it to its data link layer.

The data link layer removes the frame header and trailer, then

passes the packet to the upper layer - network layer. Then the

network layer removes the IP header from the packet and passes

segment to the transport layer. In the similar way, the transport

layer extracts the original data and delivers it to the top layer, the

application layer.

The process of encapsulation or de-capsulation is done layer by

layer. Each layer of the TCP/IP has to deal with data both from its

upper and lower layers by adding or deleting packet headers.

Page55

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The main functions of the physical layer are:

It specifies the media, interface and signaling types.

It specify the electrical, mechanical, procedural, and functional

requirements for activating, maintaining, and deactivating a physical

link between end systems.

It specify the features such as voltage, wire speed, maximum transmission distance and pin-out.

The physical layer provides standards of the transmission media

and connectors.

The common physical layer standards include IEEE 802.3 for

Ethernet, IEEE 802.4 for token bus networks, IEEE 802.5 for token

ring networks and Fiber Distributed Data Interface (FDDI) specified

by the X3T9.5 committee of ANSI. The common physical layer

standard for WANs include EIA/TIA-232 (RS-232), V.24 and V.35

developed by ITU for serial ports and G.703, which involves the

physical and electrical and electronic standards for all digital

interfaces.

Page56

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Physical layer mediums include coaxial cable, twisted pair, fiber and

wireless radio. Coaxial cable is an electrical cable consisting of a

round conducting wire. The coaxial cable can be grouped into thick

coaxial cable and thin coaxial cable according to their diameters.

The thick coaxial cable is more suitable for large LANs since its

transmission distance is longer and it is more reliable. The thick

coaxial cable does not need to be cut but you must install transceiver

for networks using thick coaxial cable. The thin coaxial cable is easy

to install and is much cheaper, but you need to cut the thin coaxial

cable and put basic network connectors (BNC) on its two sides and

then inserts the two sides into T-shape connectors when installing

the cable. So when there are many connectors, the safety is

influenced.

Page57

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Twisted pair is the most widely used cable, which is twisted by a

pair of insulated copper wires whose diameters are about 1mm.

Twisted pair has two types: Shielded Twisted Pair (STP) and

Unshielded Twisted Pair (UTP) . STP cabling includes metal

shielding over each individual pair of copper wires, so it is very

capable of keeping electromagnetic interferences and wireless

radio interference at bay. STP is easy to install but its price is

comparatively high. UTP is easy to install and its price is cheaper,

however, its capability of anti-interference is not as powerful as

that of STP and its transmission distance is not that long.

Fiber consists of fiberglass and the shielding layer and it will not

be interfered by electromagnetic signals. The transmission speed

of fiber is fast and the transmission distance is long, but fiber is

very expensive. Optical fiber connectors are connectors for the

light, which are very smooth and should not have any cuts.

Fiber connectors are not installed easily.

Wireless radio makes communications without physical links.

Wireless radio refers to electromagnetic waves with frequencies

within the radio frequency that are transmitted in the space

including the air and vacuum. We should put all the aspects into

consideration such as the distance, price, bandwidth requirement,

cables that the network devices support etc. when we make a

choice of physical medium.

Repeaters and hubs are devices working at the physical layer,

but with the development of networks, they are not used so much

as in the past. Well not discuss them here.

Page58

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Data link layer is the first logical layer of the physical layer. It encodes physical address for terminals and help network devices decide whether to pass data to upper layers along the protocol stack. It also points out which protocol the data should be delivered to with some of its fields and at the same time, it provides functions like sequencing and traffic control.

The data link layer has two sub-layers: Logical Link Control sub-layer (LLC) and Media Access Control sub-layer (MAC) .

LLC lies between the network layer and the MAC sub-layer. This sub-layer is responsible for identifying protocols and encapsulating data for transmission. The LLC sub-layer performs most functions of the data link layer and some functions of the network layer such as sending and receiving frames. When it sends a frame,it adds the address and CRC to the original data. When it receives a frame, it takes apart the frame and performs address identification and CRC. It also provides flow control, frame sequence check, and error recovery. Besides these, it can perform some of the network functions including datagram, virtual links and multiplexing.

The MAC sub-layer defines how data is transmitted through physical links. It communicates with the physical layer, specifies physical addresses, network topology, and line standards and performs error notification, sequence transmission and traffic control etc.

Page59

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Data link layer protocols specify the frame encapsulation at the data link layer. A common data link layer protocol for LANs is IEEE 802.2LLC.

Common data link layer protocols for WANs include High-level Data Link Control (HDLC) , Point-to-Point Protocol (PPP) and Frame Relay (FR).

HDLC is a bit-oriented synchronous data link layer protocol developed by the ISO. HDLC specifies data encapsulation for synchronous serial links with frame characters and CRC.

PPP is defined by Request For Comment (RFC) 1661. PPP consists of the Link Control Protocol (LCP) , the Network Control Protocol (NCP) and other PPP extended protocol stacks. PPP is commonly used to act as a data link layer protocol for connection over synchronous and asynchronous circuits and it supports multiple network layer protocols. PPP is the default data link layer protocol for data encapsulation of the serial ports of VRP routers.

FR is a protocol conforming with the industrial standards and it is an example of packet-switched technology. PPP uses error verification mechanism, which speeds up data transmission.

Ethernet switches are common network devices work at the data link layer.

Page60

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

As every person is given a name for identification, each network

device is labeled with a physical address, namely, the MAC address.

The MAC address of a network device is unique globally. A MAC

address consists of 48 binary digits and is often printed in

hexadecimal digits for human use. The first six hexadecimal bits are

assigned to producers by IEEE and the last six bits are decided by

producers themselves. For example, the first six hexadecimal bits of

the MAC address of Huaweis products is 0x00e0fc.

Network Interface Card (NIC) has a fixed MAC address. Most NIC

producers burn the MAC address of their products into the ROM.

When an NIC is initialized, the MAC address in the ROM is read into

the RAM. When you insert a new NIC into a computer, the physical

address of the computer is replaced by the physical address of the

NIC.

However if you insert two NICs into your computer, then your

computer may have two MAC addresses, so a network device may

have multiple MAC addresses.

Page61

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The data link layer ensures that datagram are forwarded between

devices on the same network, while the network layer is responsible

for forwarding packets from source to destination across networks.

The functions of the network layer can be generalized as follows:

Provide logical addresses for transmission across networks.

Routing: to forward packets from one network to another.

The router is a common network device that works at the network

layer. Routers functions mainly for forwarding packets among

networks. In the above figure,Host A and Host B reside on different

networks or links. When the router that resides on the same network

as Host A receives frames from Host A, the router passes those

frames to the network layer after it ensures that the frames should be

sent to itself by analyzing the frame header. Then the network layer

checks where those frames should go according to the destination

address in the network layer header and later it forwards those

frames to the next hop. The process repeats until the frames are sent

to Host B.

Page62

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Common network layer protocols include the Internet Protocol (IP) ,

the Internet Control Message Protocol (ICMP) , the Address

Resolution Protocol (ARP) and the Reverse Address Resolution

Protocol (RARP) .

IP is the most important one among the network layer protocols and

its functions represent the main functions of the network layer. The

functions of IP include providing logical address, routing and

encapsulating or de-encapsulating packets. ICMP, ARP and RARP

facilitate IP to achieve the network layer functions.

ICMP is a management protocol and it provides information for IP.

ICMP information is carried by IP packets.

ARP maps an IP address to a hardware address, which is the

standard method for finding a host's hardware address when only its

network layer address is known.

RARP maps a hardware address to an IP address, which means to

get a hosts IP address through its hardware address.

Page63

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The network layer address we mentioned here refers to the IP

address. The IP address is a logical address instead of a hardware

address. The hardware address such as the MAC address, is

burned on the NIC and it is for the communication between devices

that are on the same link. However, the IP address is used for

communication between devices on different networks.

An IP address is 4-byte long and is made up of the network address

and the host address. It is often presented in dotted decimal notation,

for example, 10.8.2.48.

More information about the IP address will be introduced in later

chapters.

Page64

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The transport layer provides transparent transfer of data between

hosts. It shields the complexity of communications for the upper

applications and is usually responsible for end-to-end connection.

The main functions of the transport layer involve:

Encapsulate data received from the application layer and decapsulate data received from the network layer.

Create end-to-end connections to transmit data streams.

Send data segments from one host to another, perform error recovery, flow control, and ensure complete data transfer.

Some of the transport layer protocols ensure data are transmitted correctly which means data are not lost or changed during

transmission and the order of data packets remains the same when

they are received at the end.

Page65

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Transport layer protocols mainly include the Transmission Control

Protocol (TCP) and the User Datagram Protocol (UDP) .

Page66

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Although TCP and UDP are both protocols of the transport layer, their contributions to the application layer differ greatly.

TCP provides connection-oriented and reliable transmission. Connection-oriented transmission means that applications which use TCP as their transport layer protocol need to create a TCP connection before they exchange data.

TCP provides reliable transmission services for the upper layer through its mechanisms of error detection, verification and reassembly. However, creating the TCP connection and performing these mechanisms may bring a lot of extra efforts and increase the cost.

UDP does not guarantee reliability or ordering in the way that TCP does. It provides a simpler service that does not guarantee the reliability which means datagrams may arrive out of order, appear duplicated, or go missing without notice. UDP focuses on applications that require more on transmission efficiency such as SNMP and Radius. Take SNMP as an example, it monitors networks and sends out warnings from time to time. If SNMP is demanded to create a TCP connection every time when it sends a small amount of information, undoubtedly, the transmission efficiency will be affected. So time-sensitive applications like SNMP and Radius often use UDP as their transport layer protocol. Besides this, UDP is also appropriate for applications that are equipped with some mechanisms for reliability by themselves.

Page67

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The main functions of the application layer are:

Provide user interfaces and deal with specific applications.

Provide data encryption, de-encryption, compression and decompression.

Specify the standards of data presentation.

Page68

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The application layer has many protocols and the following protocols

may help you use and manage a TCP/IP network.

File Transfer Protocol (FTP) is used to transfer data from one computer to another over the Internet, or through a network. It is

often used for interactive user sessions.

Hypertext Transfer Protocol (HTTP) is a communication protocol used to transfer or convey information on the World Wide Web.

TELNET is used to transmit data that carries the Telnet control information. It provides standards for interacting with terminal

devices or terminal processing. Telnet supports end-to-end

connections and process-to-process distributed communications.

Simple Message Transfer Protocol (SMTP) and Post Office Protocol 3 (POP3) are for sending and receiving emails.

DNS (Domain Name Server) translates a domain name to an IP address and allows decentralized management on domain resources.

Trivial File Transfer Protocol (TFTP ) is a very simple file transfer protocol. TFTP is designed for high throughput file transfer for

ordinary purposes.

Page69

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Routing Information Protocol (RIP) is the protocol for routers to change routing information through an IP network.

Simple Network Management Protocol (SNMP) collects network management information and makes that information exchanged

between the network management control console and network

devices including routers, bridges and servers.

Remote Authentication Dial In User Service (Radius) performs user authorization, authentication and accounting.

Page70

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

To illustrate the encapsulation process, imagine there is network

whose transport layer uses TCP, the network layer applies IP and

the data link layer takes Ethernet standards. The above figure

shows the encapsulation of a TCP/IP packet on that network.

The original data is encapsulated and delivered to the transport

layer. And then the transport layer adds a TCP header to the data

and passes it down to the network layer. The network layer

encapsulates the IP header in front of the segment and delivers it to

the data link layer. The data link layer encapsulates Ethernet

header and trailer to the IP packet and then passes it to the

physical layer. At last, the physical layer sends the data to the

physical link as bit streams. The length of each field in the header is

pointed out in the above figure. Now, well take a close look into the whole process from the top to the bottom.

Page72

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The above is a TCP data segment encapsulated in an IP packet. The

TCP segment consists of the TCP header and the TCP data. The

maximum length of a TCP header is 60 bytes. If there is not the

Option field, normally, the header is 20-bytes long.

The structure of a TCP header is shown as in the above figure. We

are going to explain just some of it. For more details, please refer to

the transport layer protocols.

Source Port: Indicates the source port number. TCP allocates source port numbers for every application.

Destination Port: Indicates the destination port number.

Sequence Number: Indicates the sequence number which labels TCP data streams.

Port number is used to distinguish applications,80 means HTTP application,23 for telnet,20 and 21 for ftp,53 for DNS.

Ack Num: Indicates the acknowledgement sequence number. Ack Num includes the next sequence number that the sender expects.

The value of this field is the sequence number that the sender of the

acknowledgement expects next.

Option: Indicates the optional fields.

Page73

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The network layer adds the IP header to TCP datagram which it

receives from the transport layer. Usually, the IP header has a fixed

length of 20 bytes which does not include the IP options. The IP

header consists of the following fields:

Version: indicates the version of the IP protocol. At present, the version is 4. The version is 6 for the next generation IP protocol.

IP header length is the number of 32-bit words forming the header including options. Since it is a 4-bit field, its maximum length is 60

bytes.

TOS: 8 bits. It consists of a 3-bit COS (Class of Service) field, a 4-bit TOS field and a 1-bit final bit. The 4 bits of the TOS field indicates

the minimum delay, the

maximum throughput, the highest reliability and the minimum cost

respectively.

Total length: indicates the length of the whole IP packet including the original data. This field is 16 bit long which means an IP packet

can be 65535 bytes at most. Although an IP packet can be up to

65535 byte long, most data link layers segment them before

transmission. Furthermore, hosts cannot receive a packet more than

576 bytes and UDP limits packets within 512 bytes. However,

Page74

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

nowadays many applications allow IP datagram that are more

than 8192 bytes to go through the links especially for

applications that support NFS.

Identification: identifies every datagram the host sends. The value increases with the number of datagram the host sends.

Time to Live (TTL) : indicates the number of routers a packet can travel through. The value decreases one every time the

packet passes a router. When the value turns to 0, the packet

will be discarded.

Protocol: indicates the next level protocol used in the data portion of the internet datagram. It is similar to the port number.

IP protocols use protocol number to mark upper layer protocols.

The protocol number of TCP is 6 and the protocol number of

UDP is 17.

Header checksum: calculates the checksum of the IP header to see if the header is complete.

The source IP address field and the destination IP address filed point out the IP addresses of the source and the destination.

Page75

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The physical layer has limitations on the length of frame it sends

every time. Whenever the network layer receives an IP

datagram, it needs to decide which interface the

datagram should choose and check the MTU of that

interface. IP uses a technique called fragmentation to

solve the problem of heterogeneous MTUs.

When a datagram is longer than the MTU of the network over which

it must be sent, it is divided into smaller fragments which

are sent separately.

Fragmentation can be done on the source host or the intermediary

router.

Fragments of an IP datagram are not reassembled until they arrive

at the final destination. The reassembly is performed by

the IP layer at the destination.

Datagram can be fragmented for more than one time. The IP

header provides enough information for fragmentation and

reassembly.

Page76

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

Flags: 3 bits

Multiple control bits:

0bit: reserved, must be 0.

1bit: (DF) 0 = can be fragmented, 1 = cannot be

fragmented.

2bit: (MF) 0 = final fragmentation, 1 = more

fragmentation.

The values of DF and MF cannot be 1 at the same time.

0 1 2

+---+---+---+

| | D | M |

| 0 | F | F |

+---+---+---+

Fragment offset: indicates the position of the fragment within the original datagram. When an IP datagram is fragmented,

each fragment becomes a packet with its own IP

header and will be routed independently of any other

datagrams.

Page77

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The Ethernet header is made up of three fields:

DMAC: indicates the MAC address of the destination.

SMAC: indicates the MAC address of the source.

LENGTH/TYPE: its meanings vary with its values.

When the value is bigger than 1500, it indicates the frame type, for example the upper layer protocol type. The common

protocol types are:

0X0800 IP packets

0X0806 ARP request/response message

0X8035 RARP request/response message

When the value is smaller than 1500, it indicates the length of data frame.

DATA/PAD: the original data. Ethernet standards specify that the minimum data length should be 46 bytes. If the data is less than

46 bytes, add the Pad field to fill it.

FCS: the frame check field.

Page78

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The above is an example of an HTTP packet that is captured, which

may facilitate your understanding towards packet encapsulation. The

bottom displays the actual data and the top is information analyzed

by the software.

Page80

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

This page illustrates data encapsulation at the data link layer. The

encapsulation format used here is Ethernet, which is mentioned

earlier.

The figure above shows DMAC at the top and then comes SMAC

and the type field is listed at the bottom.

DMAC is 00d0: f838: 43cf

SMAC is 0011: 5b66: 6666

Type field value is 0x0800, which indicates that it is an IP packet.

Page81

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

This page illustrates data encapsulation at the network layer. An IP

packet is made up of two parts, the IP header and the IP data. As

described previously, the IP header consists of many fields. In the

above example, the value of the version field is 4, which indicates

the packet is an IPv4 packet. The packet header is 20-byte long.

The protocol field is 0x06, which tells us that the packet to be

encapsulated is a TCP packet. The IP address of the source is

192.168.0.123 and the IP address of the destination is

202.109.72.70.

Page82

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

This page illustrates data encapsulation at the transport layer. The

transport layer here uses TCP protocols. The source port number is

a random number 3514 and the destination port number is 80,

which is the number assigned for the HTTP protocol. So the

datagram is from the source to visit the HTTP service of the

destination host.

Page83

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

1. What are the layers of the OSI reference model?

The OSI reference model consists of seven layers, namely, the

physical layer, the data link layer, the network layer, the transport

layer, the session layer and the application layer.

2. What are the functions of each layer in the TCP/IP protocol stack?

The TCP/IP protocol stack has five layers: the physical layer, the

data link layer, the network layer, the transport layer and the

application layer. The physical layer specifies the mechanical,

electrical and electronic standards for transmission. The data link

layer provides controls on the physical layer, detects errors and

performs traffic control (optional). The network layer checks the

network topology to decide the best route for data transmission. The

basic function of the transport layer is to segment the data it

received from the application layer and combines data segments

before it sends the data to the application layer. It builds end-to-end

connections to send data segments from one host to the other host.

The application layer provides network services for application

programs.

Page84

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

3. What is the process of packet encapsulation and de-

encapsulation?

De-encapsulation is the reverse process of encapsulation.

Encapsulation means to add headers to the original data layer by

layer from the top of the protocol stack to

the bottom; while de-encapsulation is to strip off those headers

from the lower layers to the upper layers.

4. What are the differences between the MAC address and the

IP address?

MAC address is a 48-byte physical address printed on the

hardware of a device. The MAC address cant be changed. The IP address is a 32-byte address works at the network layer and

IP addresses can be changed. IP addresses are grouped into

public addresses and private addresses. Public addresses are

unique globally, while private addresses can be used repetitively

in different LAN segments.

Page85

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

In TCP/IP protocols, each layer has its own communication method,

Data Link Layer use MAC Addresses, the Network Layer use IP

Addresses. After understanding the functions of these layers, this

course mainly introduces IP Addressing used at the Network Layer,

as well as packet forwarding between Network Layer devices,

which is the basis for routing.

This chapter introduces the layer 3 Network Layer in TCP/IP protocols. The main function of the Network Layer is achieved

through using the IP protocol, which includes IP Addressing and IP

Routing.

Page87

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

As the slide shows, this procedure is called encapsulation, in which

data is transferred along the TCP/IP protocol stack, from the upper

layer downward, meanwhile, corresponding header and trailer are

added. After the data encapsulation and transmission in the

network, the receiving equipment will delete the information added,

and decide how to deliver the data to proper application along the

TCP/IP protocol stack, according to the information in the header.

Among different layers of TCP/IP model, information is exchanged

to ensure the communication between network equipment. The

PDU is used for exchanging information. The PDU is different for

different layers, and with different names. For instance, in the

transport layer, the PDU with TCP layer is called a segment; after

the segment is transmitted to network layer, and added with an IP

header, the PDU is called a packet. The PDU with layer 2 header is

called a frame. Finally, the frame is processed as bits, and

transmitted through network media.

Page90

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

The network layer receives data from the transport layer, and adds source address and destination address into the data. As learned in previous chapters, the data link layer has the physical address (MAC address), which is globally unique. When there is data to be sent, the source network equipment queries the MAC address of the other end equipment, and sends it out.

However, the MAC addresses are existent in a flat address space, without clear address classification. Thus, it is only suitable for the communication within the same network segment. Besides, the MAC address is fixed in the hardware, with poor flexibility. Hence, for communication between different networks, usually it is based on IP address based on software, to provide better flexibility.

Page91

More

Learning

Resources:

http://l

earning.h

uawei.c

om/e

n

IP address is composed of 32 bits, which are divided into four

octets, or four bytes.

The IP address could be represented in the following methods:

Dotted decimal format:10.110.128.111

Binary format00001010.01101110.10000000.01101111

Hexadecimal format:0a.7e.80.7f

Usually, IP addresses are represented in the dotted decimal format;

and seldom in hexadecimal format. The hierarchical scheme for IP

addresses is composed of two parts, network and host.

The hierarchical scheme of IP addresses is similar to that of

telephone numbering, which is also globally unique. For example,

the telephone number 010-8288248: the 010 represents the city

code of Beijing, and 82882484 represents a telephone in Beijing

city. It is the same for IP addresses. The preceding network part of

an address represents a network segment, while the latter host

portion represents the device in a given

HCNA(HCDA) Huawei Certified Network Associate Training.pdf

Documents

Transcript of HCNA(HCDA) Huawei Certified Network Associate Training.pdf