Shulou(Shulou.com)06/01 Report--

Day 16 of Linux: (August 31) Linux Network Management

The content of this chapter

Network concept

OSI model

Network equipment

TCP/IP

IP address

What is the Internet?

Functions and advantages of resource sharing

Data and applications

Resources

Network storage

Backup equipment

Common network physical components

Network application program

Web browser (Chrome, IE, Firefox, etc.)

Instant messaging (QQ, Wechat, nails, etc.)

Email (Outlook, foxmail, etc.)

Collaboration (video conferencing, VNC, Netmeeting, WebEx, etc.)

Web Network Services (apache,nginx,IIS)

File Network Service (ftp,nfs,samba)

Database Services (MySQL,MariaDB, MongoDB)

Middleware Service (Tomcat,JBoss)

Security Services (Netfilter)

The impact of user applications on the network

Batch application

FTP, TFTP, inventory updates

No need for direct human interaction

Bandwidth is important, but not a critical factor

Interactive application

Inventory query, database update.

Human-computer interaction.

Because users need to wait for a response, response time is important, but not a critical factor, unless you have to wait a long time.

Real-time application

VoIP, video

Human interaction

End-to-end delay is critical

Characteristics of the network

Speed

Cost

Security.

Usability

Expandability

Reliability.

Topological structure

Physical topology classification

Logical topology

Bus topology

All devices can receive signals

Star topology

Transmit through the central point

Single point of failure

Extended star topology

Is more resilient than a star topology.

Ring topology

Signal transmission around the ring

Single point of failure

Double ring topology

The signal is transmitted in the opposite direction

More resilient than a single ring.

Full mesh topology

Strong fault tolerance

High cost of implementation

Partial mesh topology

Find a balance between fault tolerance and cost

Understand host-to-host communication

Old model

Proprietary product

Applications and embedded software are controlled by one vendor

Standards-based model

Multi-vendor software

Stratification method

Why use a hierarchical network model

Reduce complexity

Standardized interface

Simplified modular design

Ensure interoperability of technology

Accelerate the speed of development

Simplify teaching

Seven-layer structure of OSI Model

Data encapsulation

Data unencapsulation

Peer to peer communication

DD unicast

Three communication modes

Local area network Local Area Network

LAN composition

Computers

PCs

Servers

Interconnections

NICs

Media

Network devices

Hubs

Switches

Routers

Protocols

Ethernet

IP

ARP

DHCP

Network cables and interfaces

Coaxial

ThinNet

ThickNet

10Base2, 10Base5

Fiber-Optic

Twisted-Pair

Unshielded (UTP)

Shielded (STP)

10BaseT

Unshielded twisted pair UTP

Unshielded Twisted-Pair Cable

UTP

RJ-45 Connector and Jack

UTP through Line (Straight-Through)

Cable 10BASE-T/

100BASE-TX Straight-Through

Straight-Through Cable

Wires on cable endsare in same order.

Cable 10BASE-T or

100BASE-TX Straight-Through

Crossover Cable

Some wires on cableends are crossed.

EIA/TIA T568A

EIA/TIA T568B

UTP Cross Line (Crossover)

UTP straight through and crossover lines

1000BASE-T GBIC

GBIC, the abbreviation of Giga Bitrate Interface Converter, is an interface device that converts gigabit electrical signals into optical signals.

Fiber-Optic GBICs

Short wavelength (1000BASE-SX)

Long wavelength/long haul (1000BASE-LX/LH)

Extended distance (1000BASE-ZX)

Network adapter

Ethernet Evolution

LAN standard

Ethernet Frame structure

Data link layer

MAC address

MAC address

Carrier sense multiple access CSMA/CD for collision detection

Hub hub

Hub: multi-port repeater

Hub does not remember which MAC address the packet was sent from and which MAC address is on which port of Hub

Characteristics of Hub:

Shared bandwidth

Half duplex

Hub

Ethernet bridge

Advantages of switched Ethernet

Expanded network bandwidth

The network conflict domain is divided so that the network conflict is limited to a minimum.

As a more intelligent switching device, the switch can provide the functions required by more users: priority, virtual network, remote detection.

Ethernet Bridge listens to the source MAC address in the data frame, learns MAC, and establishes the MAC table

For unknown MAC addresses, the bridge forwards to all ports except the port on which the frame was received

When a bridge receives a data frame, if the destination of the frame is on the same network segment as the receiving port, it filters out the data frame; if the destination MAC address is on another port, the bridge forwards the frame to that port

When the bridge receives a broadcast frame, it is immediately forwarded to all ports except the receiving port

How Ethernet Bridge works

Comparison between Hub and switch

Hubs belong to OSI layer 1 physical layer devices, while bridges belong to layer 2 data link layer devices of OSI

From the point of view of the way it works, a hub is a broadcast mode, with all ports in a collision domain. The bridge can isolate conflicts through the port

Hub is all shared buses and shared bandwidth. Each port of the bridge occupies one bandwidth.

In order to achieve routing, the router needs to do the following:

Separate broadcast domain

Choose the best path to the destination in the routing table

Maintain and check routing information

Connect the wide area network

Router

Routing: sending a packet from one device to another in a different network. This work is done by the router. The router is only concerned with the state of the network and determining the best path in the network. The implementation of routing depends on the routing table in the router.

VLAN

VLAN = broadcast domain = logical network (Subnet)

Secure and flexible management of separate broadcast domains

Hierarchical network architecture

Distribution layer DistributionLayer

Broadcast domain, routing, security, remote access, access layer aggregation

Core layer Core Layer

Enterprise-class application fast forwarding

Access layer AccessLayer

Terminal access

Transmission Control Protocol/Internet Protocol

Transmission control protocol / Internet interconnection protocol

TCP/IP is a Protocol Stack, including TCP, IP, UDP, ICMP, RIP, TELNET, FTP, SMTP, ARP and many other protocols

It originated from the ARPA project, the predecessor of the Internet of the U.S. Department of Defense (DoD). On January 1, 1983, TCP/IP replaced the old network control protocol NCP and became the cornerstone and standard of today's Internet and local area network. It is maintained by the Internet Engineering Task Force.

There is a corresponding relationship between the four layers and the layering of the ISO reference model.

TCP/IP protocol stack

TCP/IP protocol stack and OSI model

File transfer

-FTP

-TFTP

-Network File System

E-mail

-Simple Mail Transfer Protocol

Remote login

-Telnet

-rlogin

Network management

-Simple Network Management Protocol

Name management

-Domain Name System

TCP/IP application layer

Transport layer

Session multiplexing

Segmentation

Flow control (when required)

Connection-oriented (when required)

Reliability (when required)

Reliability vs. High efficiency

TCP characteristics

Work at the transport level to the connection protocol

Duplex mode operation

Error check

Packet sequence

Confirmation mechanism

Data recovery characteristics

TCP header

Establish a link

Three-way handshake

CTL = Which control bits in the TCP header are set to 1

TCP confirmation

Fixed window

TCP sliding window

Map the fourth layer to the application

TCP port number

Working at the transport layer

Provide unreliable network access

Non-connection oriented protocol

Limited error checking

High transmission performance

Myriad data recovery features

UDP characteristics

UDP header

Internet layer

Internet Protocol (IP)

Internet Control Message Protocol (ICMP)

Address Resolution Protocol (ARP)

Reverse Address

Resolution Protocol (RARP)

Application

Transport

Internet

Data Link

Physical

Internet Control Message Protocol

Application

Transport

Internet

Data Link

Physical

Destination Unreachable

Echo (Ping)

Other

ICMP

Address Resolution Protocol

Map IPEthernet

Local ARP

Reverse ARP

Map Ethernet IP

What is my IP address?

Ethernet: 0800.0020.1111

IP: 172.16.3.25

Ethernet: 0800.0020.1111 IP =?

I heard that broadcast. Your IP address is 172.16.3.25.

Characteristics of Internet protocol

Runs at the OSI network layer

Connectionless protocol

Process packets independently

Hierarchical addressing

Best-effort transmission

Countless data recovery function

IP PDU header

Protocol domain

TransportLayer

InternetLayer

TCP

UDP

ProtocolNumbers

IP

IP address

They uniquely identify each device in the IP network

Each host (computer, network device, peripheral) must have a unique address

The IP address consists of two parts:

Network ID:

Identify the network

Each network segment is assigned a network ID

Host ID:

Identify a single host

Assigned to each device by the organization

IPv4 address format: dotted decimal notation

IP address classification

Category A:

0000 0000-0111 1111: 1-127

Number of networks: 126127

Number of hosts per network: 2 ^ 24-2

Default subnet mask: 255.0.0.0

Private address: 10.0.0.0

Category B:

10 00 0000-10 11 1111 purge 128-191

Number of networks: 2 ^ 14

Number of hosts per network: 2 ^ 16-2

Default subnet mask: 255.255.0.0

Private address: 172.16.0.0-172.31.0.0

Class C:

1 0000-110 1 1111: 192,223

Number of networks: 2 ^ 21

Number of hosts per network: 2 ^ 8-2

Default subnet mask: 255.255.255.0

Private address: 192.168.0.0-192.168.255.0

Class D: multicast

1110 0000-1110 1111: 224239

Category E:

240-255

Private address range

A

10.0.0.0 to 10.255.255.255

B

172.16.0.0 to 172.31.255.255

C

192.168.0.0 to 192.168.255.255

Special address

0.0.0.0

0.0.0.0 is not a true IP address. It represents a collection: all unknown hosts and destination networks.

255.255.255.255

Restrict broadcast addresses. For the local machine, this address refers to all hosts in the local network segment (the same broadcast domain)

127.0.0.1127.255.255.254

The local loopback address is mainly used for testing. A packet with a destination address of "127.0.0.1" should never appear on the transmission media.

224.0.0.0 to 239.255.255.255

The multicast address, 224.0.0.1 refers specifically to all hosts, and 224.0.0.2 refers to all routers. 224.0.0.5 refers to the OSPF router, the address is mostly used for some specific programs and multimedia programs

169.254.x.x

If the Windows host uses DHCP to automatically assign the IP address and cannot obtain the address from the DHCP server, the system assigns such an address to the host.

Cross-network communication

Cross-network communication: routin

Route classification:

Host routin

Network routing

Default rout

Priority: the higher precision, the higher priority

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