unit-1. overview peer-to-peer networks server based networks broadcast networks point-to-point...

87
UNIT-1

Upload: holly-josephine-knight

Post on 17-Dec-2015

234 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

UNIT-1

Page 2: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Overview• Peer-to-Peer Networks• Server based Networks• Broadcast Networks• Point-to-Point Networks• Circuit Switching.• Packet Switching.• Message Switching.• Datagram & Virtual Circuit Network• Networking Devices

Page 3: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

What is Peer-to-Peer?

• A model of communication where every node in the network acts alike.

• As opposed to the Client-Server model, where one node provides services and other nodes use the services.

Page 4: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Advantages of P2P Network

• No central point of failure– E.g., the Internet and the Web do not have a central point

of failure.– Most internet and web services use the client-server

model (e.g. HTTP), so a specific service does have a central point of failure.

• Scalability– Since every peer is alike, it is possible to add more peers to

the system and scale to larger networks.

Page 5: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Disadvantages of P2P Computing

• Decentralized coordination– How to keep global state consistent?– Need for distributed coherency protocols.

• All nodes are not created equal.– Computing power, bandwidth have an impact on

overall performance.• Programmability

– As a corollary of decentralized coordination.

Page 6: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

P2P Computing Applications

• File sharing

• Process sharing

• Collaborative environments

Page 7: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

P2P File Sharing Applications

• Improves data availability• Replication to compensate for failures.• E.g., Napster, Gnutella, Freenet, KaZaA

(FastTrack).

Page 8: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

P2P Process Sharing Applications

• For large-scale computations• Data analysis, data mining, scientific

computing• E.g., distributed.net, World-Wide Computer

Page 9: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

P2P Collaborative Applications

• For remote real-time human collaboration.• Instant messaging, virtual meetings, shared

whiteboards, teleconferencing, tele-presence.• E.g., talk, AOL Messenger, Yahoo! Messenger,

Jabber, MS Netmeeting, NCSA Habanero, Games

Page 10: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

P2P Technical Challenges

• Peer identification • Routing protocols• Network topologies• Peer discovery• Communication/coordination protocols• Quality of service• Security• Fine-grained resource management

Page 11: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

P2P Topologies

• Centralized

• Ring

• Hierarchical

• Decentralized• Hybrid

Page 12: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Centralized

ManageableCoherent

ExtensibleFault Tolerant

SecureLawsuit-proof

Scalable

System is all in one place All information is in one placeX No one can add on to systemX Single point of failure Simply secure one hostX Easy to shut down? One machine. But in practice?

Page 13: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Ring

ManageableCoherent

ExtensibleFault Tolerant

SecureLawsuit-proof

Scalable

Simple rules for relationships Easy logic for stateX Only ring owner can add Fail-over to next host As long as ring has one ownerX Shut down owner Just add more hosts

Page 14: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Hierarchical

ManageableCoherent

ExtensibleFault Tolerant

SecureLawsuit-proof

Scalable

½Chain of authority½Cache consistency½Add more leaves, rebalance½Root is vulnerableX Too easy to spoof linksX Just shut down the root Hugely scalable – DNS

Page 15: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Decentralized

ManageableCoherent

ExtensibleFault Tolerant

SecureLawsuit-proof

Scalable

X Very difficult, many ownersX Difficult, unreliable peers Anyone can join in! RedundancyX Difficult, open research No one to sue? Theory – yes : Practice – no

Page 16: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Centralized + Ring

ManageableCoherent

ExtensibleFault Tolerant

SecureLawsuit-proof

Scalable

Just manage the ring As coherent as ringX No more than ring Ring is a huge win As secure as ringX Still single place to shut down Ring is a huge win

Common architecture for web applications

Page 17: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Centralized + Decentralized

ManageableCoherent

ExtensibleFault Tolerant

SecureLawsuit-proof

Scalable

X Same as decentralized½Better than decentralized Anyone can still join! Plenty of redundancyX Same as decentralized Still no one to sue? Looking very hopeful

Best architecture for P2P networks?

Page 18: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Napster

• The P2P revolution is started.• Central indexing and searching service• File downloading in a peer-to-peer point-to-

point manner.

Page 19: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Gnutella

• Peer-to-peer indexing and searching service.• Peer-to-peer point-to-point file downloading

using HTTP.• A gnutella node needs a server (or a set of

servers) to “start-up”… gnutellahosts.com provides a service with reliable initial connection points

But introduces a new single point of failure!But introduces a new single point of failure!

Page 20: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Freenet• Peer-to-peer indexing and searching service.• Peer-to-peer file downloading.• uses a decentralized distributed data store

to keep and deliver information, and has a suite of free software for publishing and communicating on the Web without fear of censorship

• Files served use the same route as searches (not point-to-point)– Provides for anonymity.

Page 21: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Clienthost

Serverhost

Clienthost

Server Based Networks

Page 22: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Server Based Networks

• Specialization:– Clients specialize in user interface– Servers specialize in managing data and

application logic• Sharing:

– Many clients can be supported by few servers– Often data and logic are shared among

applications and users

Page 23: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Client/server

Peer-to-peerServer

“I want to access some information”

“I want to collaborate

with my colleague”

Client

Page 24: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Distinctions

• Client-server– Asymmetric relationship– Client predominately makes requests, server

makes replies• Peer-to-peer

– Symmetric relationship

Page 25: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

ClientServer

Client

Email client sends message to server

Message is stored on POP server

Later, recipient’s email client retrieves message from server

Email application

Page 26: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Client

Server

Client

Chat clients send user’s typing to server

Chat server aggregates typing from all users and sends to all clients

Other user’s clients display aggregated typing from chat server

Chat application

Page 27: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Presentation

Applicationlogic

Shareddata

Local-area network

Note: many clients perapplication server, severalapplication servers per data server

Three-tier client/server

Page 28: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Client

Webbrowser

Webserver

Application logic

Databases and DBMS

Commongatewayinterchange

Host architecture

Application partition

Page 29: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

amazon.com

Page 30: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Broadcast Networks• Broadcast Network: Shared Communication

Medium

– Shared Medium can be a set of wires• Inside a computer, this is called a bus• All devices simultaneously connected to devices

– Originally, Ethernet was a broadcast network• All computers on local subnet connected to one another

– More examples (wireless: medium is air): cellular phones, GSM GPRS, EDGE, CDMA 1xRTT, and 1evDO

MemoryProcessorI/O

DeviceI/O

DeviceI/O

Device

Page 31: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Broadcast Networks Details

Header(Dest:2)

Body(Data)Message

ID:1(ignore)

ID:2(receive)

ID:4(ignore)

ID:3(sender)

Page 32: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Broadcast Network Arbitration• Delivery: When you broadcast a packet, how does a receiver know who it is for?

(packet goes to everyone!)– Put header on front of packet: [ Destination | Packet ]– Everyone gets packet, discards if not the target– In Ethernet, this check is done in hardware

• No OS interrupt if not for particular destination– This is layering: we’re going to build complex network protocols by layering on

top of the packet

• Arbitration: Act of negotiating use of shared medium– What if two senders try to broadcast at same time?– Concurrent activity but can’t use shared memory to coordinate!

Page 33: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Point-to-point networks

• Why have a shared bus at all? Why not simplify and only have point-to-point links + routers/switches?– Didn’t used to be cost-effective– Now, easy to make high-speed switches and routers that can forward

packets from a sender to a receiver.• Point-to-point network: a network in which every physical wire is connected to

only two computers• Switch: a bridge that transforms a shared-bus (broadcast) configuration into a

point-to-point network.• Router: a device that acts as a junction between two networks to transfer data

packets among them.

Router

Internet

Switch

Page 34: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Point-to-Point Networks• Advantages:

– Higher link performance• Can drive point-to-point link faster than broadcast link since less

capacitance/less echoes (from impedance mismatches)– Greater aggregate bandwidth than broadcast link

• Can have multiple senders at once– Can add capacity incrementally

• Add more links/switches to get more capacity– Better fault tolerance

• Disadvantages:– More expensive than having everyone share broadcast link

• Examples– ATM (asynchronous transfer mode)

• The first commercial point-to-point LAN• Inspiration taken from telephone network

– Switched Ethernet• Same packet format and signaling as broadcast Ethernet, but only two

machines on each ethernet.

Page 35: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Switching

Page 36: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Switched network

A switched network consists of a series of interlinked nodes, called switches. Switches are devices capable of creating temporary connectionsbetween two or more devices linked to the switch.For example: computers or telephones

Page 37: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Taxonomy of switched networks

Page 38: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

CIRCUIT-SWITCHED NETWORKS

A circuit-switched network consists of a set of switches connected by physical links. A connection between two stations is a dedicated path made of one or more links. However, each connection uses only one dedicated channel on each link. Each link is normally divided into n channels by using FDM or TDM.

Page 39: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

A trivial circuit-switched network

Page 40: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

In circuit switching, the resources need to be reserved during the setup phase;

the resources remain dedicated for the entire duration of data transfer until the teardown phase.

• Circuit switching takes place in Physical layer.• Data transfer between the two nodes is a continuous

flow.• No addressing is involved during data transfer.

Page 41: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

As a trivial example, let us use a circuit-switched network to connect eight telephones in a small area. Communication is through 4-kHz voice channels. We assume that each link uses FDM to connect a maximum of two voice channels. The bandwidth of each link is then 8 kHz. Figure 8.4 shows the situation. Telephone 1 is connected to telephone 7; 2 to 5; 3 to 8; and 4 to 6. Of course the situation may change when new connections are made. The switch controls the connections.

Example

Page 42: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Circuit-switched network used in Example

Page 43: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

As another example, consider a circuit-switched network that connects computers in two remote offices of a private company. The offices are connected using a T-1 line leased from a communication service provider. There are two 4 × 8 (4 inputs and 8 outputs) switches in this network. For each switch, four output ports are folded into the input ports to allow communication between computers in the same office. Four other output ports allow communication between the two offices.

Example

Page 44: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Circuit-switched network used in Example 2

Page 45: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Efficiency

• Less Because resources are allocated during the entire duration of the connection.

• In a telephone network, people normally terminate the communication when they have finished their conversation.

• However, in computer networks, a computer can be connected to another computer even if there is no activity for a long time

Page 46: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Delay: Transmission and Propagation Delay

Propagation delay between Host 1 and Switch1

Transmission delay

Host 1 Switch 1

1. Size of transfer2. Bandwidth of link

1. Speed of light2. Physical distance

• Delay Minimal• Because resources are allocated for the duration of the connection• But delay due to transmission and propagations

Page 47: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Circuit-Switched Technology in Telephone Networks

Page 48: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

DATAGRAM NETWORKS

In data communications, we need to send messages from one end system to another. If the message is going to pass through a packet-switched network, it needs to be divided into packets of fixed or variable size. The size of the packet is determined by the network and the governing protocol.

In a packet-switched network, there is no resource reservation;resources are allocated on demand.

Datagram switching is normally done at the network layer.

Page 49: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

A datagram network with four switches (routers)

Page 50: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Routing table in a datagram network

A switch in a datagram network uses a routing table that is based on the destination address.

The destination address in the header of a packet in a datagram network

remains the same during the entire journey of the packet.

Switching in the Internet is done by using the datagram approach to packet

switching at the network layer.

Page 51: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Efficiency

• The efficiency of a datagram network is better than that of a circuit-switched network;

• resources are allocated only when there are packets to be transferred..

Page 52: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Delay• There may be greater delay in a datagram network than in a virtual-circuit

network.• The packet travels through two switches. There are three transmission

times (3T),three propagation delays (slopes 3't of the lines), and two waiting times (WI + w2)' Weignore the processing time in each switch.

• Total delay =3T + 3t + WI + W2

Page 53: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Datagram Networks in the Internet

Page 54: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

VIRTUAL-CIRCUIT NETWORKS

A virtual-circuit network is a cross between a circuit-switched network and a datagram network. It has some characteristics of both.

A source or destination can be a computer,packet switch, bridge, or any other device that connects other networks

Page 55: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Virtual-circuit identifierThe identifier that is actually used for data transfer is called the virtual-circuit identifier(VCI)

Page 56: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Switch and tables in a virtual-circuit network

Page 57: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Source-to-destination data transfer in a virtual-circuit network

Page 58: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Setup request in a virtual-circuit network

Page 59: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Setup acknowledgment in a virtual-circuit network

Page 60: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

In virtual-circuit switching, all packets belonging to the same source and destination travel the same path;

but the packets may arrive at the destination with different delays if resource allocation is on demand.

Switching at the data link layer in a switched WAN is normally implemented by using virtual-circuit techniques.

Page 61: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Efficiency

• In virtual-circuit switching, all packets belonging to the same source and destination travel the same path; but the packets may arrive at the destination with different delays if resource allocation is on demand.

• Ex: Consider a family that wants to dine at a restaurant. Although the restaurant may not accept reservations (allocation of the tables is on demand), the family can call and find out the waiting time. This can save the family time and effort.

Page 62: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Delay• a one-time delay for setup and a one-time delay for teardown.• The packet is traveling through two switches (routers). There are three

transmission times (3T), three propagation times (3't), data transfer depicted by the sloping lines, a setup delay (which includes transmission and propagation in two directions), and a teardown delay (which includes transmission and propagation in one direction).

• Total delay = 3T+ 3't + setup delay + teardown delay

Page 63: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Circuit-Switched Technology in WANs

Page 64: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Message Switching

• A store-and-forward network where the block of transfer is a complete message.

• Since messages can be quite large, this can cause:– buffering problems– high mean delay times

Page 65: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Network Devices

– Repeater– Hub– Bridge– Router– Gateway

Page 66: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Connecting Devices

Networking Devices

Repeaters Bridges

InternetworkingDevices

Routers Gateways

Page 67: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Connecting Devices

Hub

Page 68: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Repeater

• Extend the physical length• No network function has been changed• Location is matter

Page 69: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Function of repeater

Repeater is not same as Amplifier

Page 70: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Hub

• Actually is a multiport repeater• Star / Tree Topology

Page 71: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Bridge

Page 72: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Bridge

• Divide a large network into smaller segment• Isolating and controlling the link problems

(e.g. congestion)• Regenerate signal + Checking Physical Address

and forward only to the specified segment

Page 73: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Function of a bridge

Page 74: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Multiport bridge

74/ 25

Page 75: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Routers

Page 76: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Routers in an internet

76/ 25

Page 77: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Routers

• Act like stations on a network• Multi-home• Definition (Goal)

– “Learning how to get from here to there." – “Process of discovering, selecting, and employing

paths from one place to another (or to many others) in a network”

Page 78: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Routing Principle

• Goal: Arriving at the destination• Considerations:

– Direct route (shortest)– Reliable route– Cheap route– Safe route– Scenic route

Page 79: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Gateways (protocol converter)

Page 80: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

A gateway

SNA network (IBM)Netware network (Novell)

Page 81: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Other devices

• Multiprotocol routers• Brouters• Switches• Routing switches

Page 82: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Single VS. Multiprotocol router

Page 83: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Brouter

Page 84: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Backbone Network

84/ 25

Bus Backbone

Star Backbone

Page 85: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Connecting Remote LAN

A point-to-point link acts as a LAN in a remote backbone connected by remote bridges

Page 86: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

Virtual LAN (VLAN)

VLANs create broadcast domains

Page 87: UNIT-1. Overview Peer-to-Peer Networks Server based Networks Broadcast Networks Point-to-Point Networks Circuit Switching. Packet Switching. Message Switching

VLAN with backbone switch