Networking Technologies

Chi So

Terms

Network – a set of devices, software, and cables that enables the exchange of information between them

Host Device – anything a person uses to access the network

Network Device – hubs, repeaters, bridges, switches, routes, and firewalls

Topologies

Point-to-Point – involves two hosts or devices that are directly connected to each other and to nothing else. i.e. Serial Communication (not always)

Star – one host or device has multiple connections to other hosts. Sometimes called hub-and-spoke. Anything that sends traffic through the

hub or central device

Topologies

Ring – when one device is connected to the next one sequentially. The last device is connected to the first. Not always a true circle Data moves in a logical circle i.e. FDDI and Token Ring

Bus – a single coaxial cable where hosts are attached at intervals. i.e. cable internet

Topologies

Mesh – multiple point-to-point connections that connect each location to the others Full Mesh – all devices are

interconnected Partial Mesh – some devices are

interconnected

Ethernet

Ethernet is the most common LAN (Local Area Network) technology

IEEE 802.3 Developed by Digital Equipment

Corp., Intel, and Xerox. Published in 1980

Ethernet

Segment – A coaxial cable that joins all the hosts together

Collision – when two hosts try to use the connection at the same time

Ethernet

Carrier Sense Multiple Access with Collision Detection (CSMA/CD) – method for Ethernet to detect collusions. Listen to the line▪ If clear, start transmission▪ If used, wait until clear

If collision occurs▪ send jam signal▪ Stop transmission▪ Wait a random time before sending again (all

hosts)

Ethernet

Collision domain – a group of devices that are affected by one another’s collusions The more hosts in a domain, the more

frequent the collision Bridges and switches help resolve this

issue

Ethernet

Half Duplex – Send or receive Full Duplex – Send and Receive

8 wires needed. 4 is possible

WAN Technologies

Wide Area Network (WAN) Interconnect two or more LANs Usually this service is bought from

another company 4 types of WAN technologies▪ Dedicated Lease Line▪ Circuit-Switched Connections▪ Packet-Switched Connections▪ Cell-Switched Connections

WAN Technologies

Dedicated Leased Line A connection that is installed and provisioned

for the exclusive use of the customer No other customer can affect the line Very expensive A lot of control (QoS, other traffic management) Usually point to point Protocols used▪ Point-to-Point Protocol (PPP)▪ High-Level Data-Link Control Protcol (HDLC)▪ Serial Line Internet Protocol (SLIP)

WAN Technologies

Circuit-Switched Connections Uses the phone company as a service

provider▪ Analog dial-up or digital ISDN connections▪ Protocols used▪ PPP▪ HDLC▪ SLIP

▪ Really slow, 19.2Kbit to 128Kbit

WAN Technologies

Packet-Switched Connections Connect to the providers network Traffic is affected by others Usual technologies are▪ Frame Relay ▪ X.25 (possible)

WAN Technologies

Cell-Switched Connections Similar to packet switched Difference is the unit size of the data is

fixed (cell)▪ In packet switched networks, data units are

called (frames) Dealing with traffic loads are typically

easier and efficient Examples▪ Asynchronous Transfer Mode (ATM)

Wireless Networks

IEEE 802.11 Advantage: Great to eliminate cables

and freedom of movement Disadvantage: range (?), reliability,

security Moderate WAN distances▪ Line of sight

Other Network Technologies

Metropolitan Area Network (MAN) Found in urban business centers

Storage Area Network (SAN) Access an external storage array as a

hard drive Expensive

Content Networks Making access to the information faster Logging and controlling access to certain

kinds of materials

OSI Model

Open Systems Interconnection (OSI) model Used to standardized networking

processes No rules imposed onto the

manufacturers or protocol developers Only guidelines 7 Layers

OSI Model

7 - Application 6 - Presentation 5 - Session 4 - Transport 3 - Network 2 - Data Link 1 - Physical

Layer 7: Application

Any application or utility that store, send or retrieve data across a network

Sometimes called the user interface layer Examples

Hypertext Transfer Protocol (HTTP) File Transfer Protocol (FTP) Simple Mail Transfer Protocol (SMTP) Post Office Protocol v3 (POP3) Network Time Protocol (NTP) Simple Network Management Protocol (SNMP) Domain Name Systems (DNS) Dynamic Host Configuration Protocol (DHCP) Secure Shell (SSH)

Layer 6: Presentation

Responsible for formatting data so that the application layer (layer 7) can recognize and work with it.

Examples .doc .jpg .txt .avi

Layer 5: Session

Deals with initiating and terminating network connections

Provides instructions to Connect Authenticate (optional) Disconnect

Movement of data is handled by lower layers

Examples Login for Telnet, SSH, SQL sessions, RPC

Layer 4: Transport

One of the most important layers Deals with how two hosts are going

to send data. Two methods: Connection-oriented (TCP)▪ Reliable

Connectionless (UDP)▪ Unreliable

Layer 3: Network Layer

Deals with logical address (usually IP address) Other possibilities▪ IPX▪ AppleTalk▪ SNA

Addresses are assigned in software IP hosts can communicate if they are on the

same network If different networks, need a router to

communicate Finding a way to communicate between two

networks is call path determination

Layer 3: Network Layer

With the data unit from Layer 4, the data segment is now called a packet ( or datagram)

Header has the following info:

Layer 3: Network Layer

Since using logical addressing Hierarchical▪ Organized into a formal or ranked order▪ Easy to build a big system▪ Build smaller systems, and put them together

▪ Example:▪ Mailing address

Layer 3: Network Layer

Protocols: Internet Protocol (IP) IPX (Novell Netware) Internet Connection Management

Protocol (ICMP) OSPF, IGRP, EIGRP, RIP, ISIS (Routing

Protocols) Address Resolution Protocol (ARP),

Reverse ARP (RARP)

Layer 2: Data Link

Takes the Layer 3 packet and preparing a frame for the packet to be transmitted

Examples: Ethernet Frame Relay Point-to-Point (PPP) High-Level Data Link Control Protocol

(HDLC) Cisco Discovery Protocol (CDP)

Layer 2: Data Link Layer

Not hierarchical Flat addressing

Address are done with Media Access Control (MAC)

MAC addresses are assigned in hardware

Layer 1: Physical Layer

Transmit the data onto a wire, optical fiber, or wireless

All signaling is digital Electricity On = 1 Electricity Off = 0 Typically RJ-45