Tài liệu giảng dạy CCNA - module 7-2 NETWORK SERVICE & NETWORK ADMINISTRATION

A workstation uses special software, such as a network shell program to perform the following tasks:  Intercepts user data and application commands  Decides if the command is for th

NETWORK SERVICE &

NETWORK ADMINISTRATION

Table of Content

1 Workstations and Servers

WORKSTATIONS AND SERVERS

Workstations

 D

Workstations

 A workstation is a client computer that is used to run applications and is connected to a server from which it obtains data shared

with other computers

 A server is a computer that runs a network operating system

(NOS) A workstation uses special software, such as a network

shell program to perform the following tasks:

 Intercepts user data and application commands

 Decides if the command is for the local operating system or

for the NOS

 Directs the command to the local operating system or to the

network interface card (NIC) for processing and transmission

onto the network

 Delivers transmissions from the network to the application

running on the workstation

 Common to classify computers and operating systems based on

the types of applications the computer runs

Servers

Servers (cont.)

 Server systems must be equipped to support multiple

concurrent users and multiple tasks

 Servers usually have high-capacity, high-speed disk drives, large amounts of RAM, high-speed NICs, and in some

cases, multiple CPUs

 These servers are typically configured to use the TCP/IP,

and offer one or more TCP/IP services

 Servers running NOSs are also used to authenticate users

and provide access to shared resources

 By centralizing user accounts, security, and access control, server-based networks simplify the work of network

administration

Servers (cont.)

 Redundancy is the inclusion of additional hardware

components that can take over if other components fail and can be repaired without interruption while the systems are

up and running

 Server applications and functions include HTTP, FTP, and

DNS

 Standard e-mail protocols supported by network servers

include SMTP, POP3, and IMAP

 File sharing protocols include Sun Microsystems NFS and

Microsoft SMB

Servers (cont.)

 Network servers frequently provide print services

 A server may also provide DHCP

 A servers can be set to act as a basic firewall for the

network This is accomplished using proxy or Network

Address Translation (NAT)

 Most organizations must deploy several servers in order to

achieve acceptable performance

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100 Mbps Switch

Admin RAS Monitoring server Firewall

1 1

1 2

Introduction to OS

 A computer operating system (OS) is the software

foundation on which computer applications and services run

on a workstation

 Common functions of an OS on a workstation include

controlling the computer hardware, executing programs

and providing a user interface

 The OS performs these functions for a single user

 When a workstation becomes a client in a NOS

environment, additional specialized software enables the

local user to access non-local or remote resources

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Introduction to NOS

 Network operating system (NOS) enables communication

between multiple devices and the sharing of resources

across a network

 A NOS operates on UNIX, Microsoft Windows NT, or

Windows 2000 network servers

 A system capable of operating as a NOS server must be

able to support multiple users concurrently

 A NOS server is a multitasking system, capable of

executing multiple tasks or processes at the same time

1 4

Popular NOS

Intranetware Sun Solaris 200 Server Caldera

1 5

monitoring System administration

Security Encryption and user authentication

Scalability Ready to growth

Robustness/fault

tolerance balancing the workload and redundant

1 6

Microsoft NT, 2000, and NET

Windows NT  Workstation

 Server

 Corporate users

 Departmental server Windows 2000 Professional

1 7

UNIX, Sun, HP

 A UNIX is the name of a group of operating systems that

trace their origins back to 1969 at Bell Labs

 Since its inception, UNIX was designed to support multiple

users and multitasking

 UNIX was also one of the first operating systems to include support for Internet networking protocols

1 8

Benefit of UNIX

 Industry standards based operating system

 Powerful, flexible, scalable, and secure

 Supported by various equipment manufactures

 Mature and state operating system

 Tightly integrated with TCP/IP Protocols

 Widely used form mission critical applications

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UNIX, Sun, HP (cont.)

 UNIX was first written in assembly language, so UNIX could only run on a specific type of computer

 In 1973, Ritchie along with fellow Bell Labs programmer

Ken Thompson rewrote the UNIX system programs in C

language, so UNIX could be moved or ported to another

computer with far less programming effort

 To be marketed commercially in the 1980s, it was used to

run powerful network servers, not desktop computers

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UNIX, Sun, HP (cont.)

 Today, there are dozens of different versions of UNIX, including

the following:

 Hewlett Packard UNIX (HP-UX)

 Berkeley Software Design, Inc (BSD UNIX), which has

produced derivatives such as FreeBSD

 Santa Cruz Operation (SCO) UNIX

 Sun Solaris

 IBM UNIX (AIX)

 Sun Solaris is a high-performance, versatile, 64-bit

implementation of UNIX

 Solaris runs on a wide variety of computers.

 Solaris is currently the most widely used version of UNIX.

 Sun is also the developer of the "Write Once, Run Anywhere" Java technology.

2 1

LINUX

 In 1991, Linus Torvalds set out to develop an operating system that was UNIX-like in its operation but used software code that was open and completely free of charge to all users.

 By the late 1990s, Linux had become a viable alternative to

UNIX on servers and Windows on the desktop.

 Versions of Linux can now run on almost any 32-bit processor, including the Intel 80386, Motorola 68000, Alpha, and

PowerPC chips.

2 2

LINUX (cont.)

 In As with UNIX, there are numerous versions of Linux

 Red Hat Linux – distributed by Red Hat Software

 OpenLinux – distributed by Caldera

 Corel Linux

 Slackware

 Debian GNU/Linux

 SuSE Linux

 Linux is one of the most powerful and reliable operating

systems in the world today

 Application support must be considered when Linux is

implemented on a desktop system

2 3

LINUX (cont.)

 Recent distributions of Linux have networking components

built in for connecting to a LAN, establishing a dialup

connection to the Internet, or other remote network In

fact, TCP/IP is integrated into the Linux kernel

 Some advantages of Linux as a desktop operating system

and network client include the following:

 It is a true 32-bit operating system

 It supports preemptive multitasking and virtual

memory

 The code is open source and thus available for

anyone to enhance and improve.

2 4

Apple

 Apple Macintosh computers were designed for easy

networking in a peer-to-peer, workgroup situation

 NIC are included as part of the hardware

 Networking components are built into the Macintosh

operating system

 Macs can be connected to one another in workgroups and

can access AppleShare file servers Macs can also be

connected to PC LANs that include Microsoft, NetWare, or

UNIX servers

2 5

Apple - Mac OS X (10)

 The Macintosh operating system, Mac OS X, is sometimes

referred to as Apple System 10

 Some of the features of Mac OS X are in the GUI called

Aqua

 Is designed to provide features for the home computer,

while still providing features that offer powerful and

customizable tools that IT professionals need

 Provides a new feature that allows for AppleTalk and

Windows connectivity

 Support for protected memory, preemptive multitasking,

advanced memory management, and symmetric

multiprocessing

2 6

Concept of service on servers

 NOSs are designed to provide network processes to clients Network services include:

 World Wide Web (WWW)

 File sharing (NFS, SMB)

 File transfer (FTP)

 E-mail (POP3, SMTP, IMAP)

 Directory services (DNS, LDAP)

 Print services (LPD)

 Remote management (Telnet, SNMP)

 Dynamic IP allocation

 Firewall (NAT)

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NETWORK MANAGEMENT

2 8

Introduction to network

management

2 9

3 0

What is driving Network

Management?

 Controlling corporate assets – If network resources are not

effectively controlled, they will not provide the results that

management requires

 Controlling complexity – With massive growth in the number of

network components, users, interfaces, protocols, and vendors,

loss of control of the network and its resources threatens

management

 Improved service – Users expect the same or improved service

as the network grows and the resources become more

distributed

 Balancing various needs – Users must be provided with various

applications at a given level of support, with specific requirements

in the areas of performance, availability, and security

 Reducing downtime – Ensure high availability of resources by

proper redundant design

 Controlling costs – Monitor and control resource utilization so

that user needs can be satisfied at a reasonable cost.

3 1

Some basic network management

terms

3 2

OSI and network management model

3 3

SNMP and CMIP standards

 Two main standards have emerged:

3 4

SNMP operation

 SNMP is an application layer protocol designed to facilitate

the exchange of management information between network devices

 Today, SNMP is the most popular protocol for managing

diverse commercial, university, and research internetworks

 Standardization activity continues even as vendors develop and release state-of-the-art SNMP-based management

applications

3 5

SNMP Components

3 6

SNMP: Management station

 Usually a standalone workstation, it includes a collection of software called the network management application (NMA) and user interface

 It responds to user commands and issued commands to

management agents throughout the network

 The NMS performs a monitoring function by retrieving the

values from maintains a database of management

information (MIB) extracted from the devices under its

management

3 7

SNMP: Management agent

 The management agent is the component that is contained

in the devices that are to be managed

 The management agent responds to the management

station in two ways:

 Polling , the management station requests data from the agent and the agent responds with

the requested data

 Trapping , the agent will send data to the

management station if a threshold that are set

on the managed device is exceeded.

3 8

SNMP: Management Information

Base

 The management information base (MIBs) has a database

structure and is resident on each device that is managed

 The database contains a series of objects, which are

resource data gathered on the managed device

 Some of the categories in the MIB include Port interface

data, TCP data, and ICMP data

3 9

SNMP: Network Management

Protocol

 An application layer protocol designed to communicate

between the management console and the management

agent

 It has three key capabilities:

 GET: the management console retrieve data

from the agent.

 PUT: the management console set object

values on the agent.

 TRAP: the agent notify the management

console of significant events

4 0

SNMP Components (cont.)

Two-tier model

Three-tier model

4 1

Network management architecture

4 2

Structure of management

information and MIBs

4 3

SNMP protocol : Agent

4 4

SNMP protocol : Protocol

4 5

SNMP protocol : Community Strings

4 6

SNMP protocol : Community Strings

4 7

Configuring SNMP

4 8

Remote MONitoring

 Standardized MIB based on SNMP

 A standard monitoring specification that enables various

network monitors and console systems to exchange data

 RMON provides network administrators with comprehensive network-fault diagnosis, planning, and performance-tuning information

 RMON was defined by IETF: RFC1271, RFC1757 (Ethernet) and RFC1513 (TR)

4 9

RMON: Extension of SNMP

 Enhances the operation and monitoring capabilities of

SNMP

 SNMP is still required for RMON to operate on a network

 The RMON extension to the SNMP protocol creates new

categories of data

 These categories add more branches to the MIB database

 When working with RMON, as with SNMP, a central

management console is the point of data collection

5 0

RMON MIB 2

5 1

RMON Groups: Ethernet Statistics

 Provides a view of the overall load and health of a

subnetwork by measuring different types of errors including CRC, collisions, over and under-sized packets

 Contains statistics gathered for each monitored

subnetwork

 Include counters (incremental that start from zero) for

bytes, packets, errors, and frame size

 The table identifies each monitored Ethernet device,

allowing counters to be kept for each individual Ethernet

device

5 2

RMON Groups: History Control

 Record samples of the counters in the Ethernet Statistics

Group over a specified period of time

 A new entry is created in the table at each sample interval

until the limit is reached

 Then as each new entry is created the oldest entry in the

table is deleted

 These samples provide a baseline of the network and can

be used to compare against the original baseline to resolve problems or to update the baseline as the network

changes

5 3

RMON Groups: Alarm

 Uses user specified limits that are called thresholds

 If the data counters being monitored cross the thresholds,

a message or alarm will be occurred

 This process, known as an error trap, can automate many

functions of network monitoring

 This is an important component of preemptive

troubleshooting

5 4

RMON Groups: Host

 Contains counters maintained about each host discovered

on the subnetwork segment

 Some of the counter categories maintained are Packets,

Octets, Errors, and Broadcasts

 Types of counters associated with each of the previously

mentioned items could be

5 5

RMON Groups: Host TOP N

 Is used to prepare reports about a group of hosts that top

a statistical list based on a measured parameter

 Example:

 A report could be generated for the top ten hosts

generating broadcasts for a day

 Another report might be generated for the most

packets transmitted during the day

 Provides an easy way to determine who and what type of

data traffic most occupies the selected subnetwork

5 6

RMON Groups: Matrix

 Records the data communication between two hosts on a

subnetwork

 This data is stored in the form of a matrix (a

multi-dimensional table)

 One of the reports that can be generated from this

category is which host utilizes a server

 Reorganizing the matrix order can create other reports For example, one report might show all users of a particular

server, while another report shows all the servers used by

a particular host

5 7

RMON Groups: Filter

 Provides a way that a management console can instruct an RMON probe to gather selected packets from a specific

interface on a particular subnetwork

 This selection is based on the use of two filters, the DATA

and the STATUS filter

 These filters can be combined to create very complicated

conditions

 The filter group allows the network administrator to

selectively look at different types of packets to provide

better network analysis and troubleshooting