CHAPTER 2CHAPTER 2

INTERNETWORKING DEVICESINTERNETWORKING DEVICES

Izaz A KhanIzaz A Khan

InternetworkingInternetworking• Combinations of different networks with one another Combinations of different networks with one another

is called Internetwork.is called Internetwork.• It is the combination of LANs and WANs.It is the combination of LANs and WANs.• The Internet is a vast connection of networks all The Internet is a vast connection of networks all

linked together and available by everyone with an linked together and available by everyone with an Internet connection.Internet connection.

• An intranet is a private network. It cannot be An intranet is a private network. It cannot be accessed by random people on the Internet. Instead, accessed by random people on the Internet. Instead, it is used for internal communication on a network of it is used for internal communication on a network of computers. Intranet computers have access to the computers. Intranet computers have access to the Internet, however.Internet, however.

Internetworking DevicesInternetworking Devices

• NICNIC

• HUBHUB

• BridgeBridge

• SwitchSwitch

• RouterRouter

1- NIC1- NIC• Network Interface Card.Network Interface Card.

• UsuallyUsually PCI PCI ((Peripheral Peripheral Component InterconnectComponent Interconnect) Card) Card• Plugs into MotherboardPlugs into Motherboard

• Communicate with network through Communicate with network through Serial ConnectionSerial Connection

• Communicate with System through Communicate with System through Parallel ConnectionParallel Connection

• Have embedded MAC/Physical Have embedded MAC/Physical Address on a chipAddress on a chip

2- HUB2- HUB• Hybrid Unit Board (HUB)Hybrid Unit Board (HUB). Its works on . Its works on

both Analog and Digital signals thatboth Analog and Digital signals that’’s why s why it is called Hybrid.it is called Hybrid.

• Connects multiple nodes in a single Connects multiple nodes in a single network segmentnetwork segment

• Works at Layer One (Physical Layer)Works at Layer One (Physical Layer)

• Broadcasting Device: Broadcasting Device: It is a It is a nonnon--intelligentintelligent device because it broadcasts device because it broadcasts the information to all the nodes attached the information to all the nodes attached to the Hub.to the Hub.

• One Collision Domain: One Collision Domain: Means one way, Means one way, one door.one door.

• Also called Also called Multi-port RepeaterMulti-port Repeater..

• It is a It is a half-duplex half-duplex device.device.

• Maximum speed is 10Mbps.Maximum speed is 10Mbps.

Broadcast DomainBroadcast Domain

• If the first PC is sending data to the fourth PC. In Hub the data will be broadcasted to all the PCs.

• So each time when a PC wants to send data to another PC, the data packets will be broadcasted to all the PCs by the hub and then only the PC which has requested for the data will receive the data packets.

Collision DOMAINCollision DOMAIN

• HUBs have one collision domain which means HUBs have one collision domain which means one way for communication (through the one way for communication (through the HUB).HUB).

• We also know that HUB is a half duplex device We also know that HUB is a half duplex device which means one way communication at a which means one way communication at a time.time.

• When two PCs connected to a HUB transmits When two PCs connected to a HUB transmits at the same time then collision occurs thatat the same time then collision occurs that’’s s why HUBs have one collision domain.why HUBs have one collision domain.

Types of HUBsTypes of HUBs

1- Passive Hubs

2- Active Hubs 3- Intelligent Hubs

• Send/Receive data

• Not Amplifier

• No monitoring port

• Send/Receive data

• Amplifier

• Monitoring port

• Two types

1. Switches

1. Bridges

BridgeBridge• Used for Network Segmentation.Used for Network Segmentation.

• Segmentation:Segmentation:• Dividing a big network into partsDividing a big network into parts

• Intelligence Device Intelligence Device (Data Packets are send to the (Data Packets are send to the specific destination instead of broadcasting).specific destination instead of broadcasting).

• Maximum speed is 100Mbps and it is Maximum speed is 100Mbps and it is full duplex full duplex for for every port due to which it has every port due to which it has separate collisionseparate collision domaindomain means there will be no collision as each means there will be no collision as each port is full duplex and will receive its own specific port is full duplex and will receive its own specific packets.packets.

• Has Has one Broadcast domainone Broadcast domain. .

• Send and receive data according to MAC addresses.Send and receive data according to MAC addresses.

• Works on Works on MAC tableMAC table..

• MAC= media access controlMAC= media access control

• Mainly have Mainly have 2,4 ports 2,4 ports and works at and works at Layer 2Layer 2. .

BridgeBridge• Consider the network in the

diagram, the first PC wants to send data to the fifth PC, for the first time the data (packets) will be broadcasted to get the MAC address of the fifth PC and and the data will be sent to the fifth PC.

• Then the MAC address of the destination (fifth PC) will be

stored in MAC table. Similarly, for every PC the data will be broadcasted for the first time only, when we are using switches and bridges.

SwitchSwitch• Similar to HUB but is an Similar to HUB but is an

intelligent devicintelligent device and have e and have more ports.more ports.

• Forwards Packets based upon Forwards Packets based upon their destination address.their destination address.

• Increase bandwidthIncrease bandwidth

• Decrease/Avoid collisionsDecrease/Avoid collisions

• Maximum speed is 100MbpsMaximum speed is 100Mbps

• Uses Uses MAC tableMAC table• Typically works on Typically works on Layer 2Layer 2. .

However, some However, some Layer 3 Layer 3 switches are also available.switches are also available.

Types of SwitchesTypes of Switches

1- Normal 2- Catalyst 3- Multi-layer• Can’t install, delete

or upgrade ios• Can’t block any port• Can’t manage• Can’t create VLANs• Used in LANs

• Install, change or delete ios

• Can block any port.• Manageable• Create VLAN• Used in LANs

• Just like catalyst switches but used in WANs

• High speed communication

• Routers commands can be used.

• Works at Layer 3

• ios= internetwork operating system.• VLAN= Short for virtual LAN, a network of computers that behave as if they

are connected to the same wire even though they may actually be physically located on different segments of a LAN.

RouterRouter• A router is a device that A router is a device that

forwards data packets from forwards data packets from one network to another.one network to another.

• RoutedRouted and and Routing Routing protocols protocols are used.are used.

• Routing protocols are used to find the best path b/w the routers.• Routed protocols are used to send/receive data b/w the routers.• Routing table is used to store all the information about the

connected routers.• In terms of security, we can block a specific IP address or group of

IP addresses, network or group of networks as well as we can also block ports and protocols.

• Uses Breakup broadcasting: Means broadcasts are not forwarded across the router. Router broadcasts to its every interface only.

• Works at Layer 3.

Collision Domain on SwitchCollision Domain on Switch

Collision Domain on HubCollision Domain on Hub

Broadcast DomainBroadcast Domain

• No matter how many hosts or devices are connected together, if they are connected with a hub, switch or bridge, all these devices are in ONE Broadcast domain.

• A Router is used to separate Broadcast-Domains.

Collision domainCollision domain

• Each port on a bridge, a switch or a router is in a separate collision domain.

Broadcast domainBroadcast domain

• All ports on a hub or a switch are by default in the same broadcast domain. All ports on a router are in the different broadcast domains and routers don't forward broadcasts from one broadcast domain to another.

• In the picture above we have three broadcast domains, since all ports on a hub or a switch are in the same broadcast domain, and all ports on a router are in a different broadcast domain.

TesT 1TesT 1

• 2 broadcast and 2 collision domains.

TesT 2TesT 2

• 1 broadcast and 4 collision domains• Because as we know, all ports on a hub or a switch are by

default in the same broadcast domain.

TesT 3TesT 3

AnswerAnswer

• 2 broadcast and 7 collision domains.

SummarySummary• From all the study it is clear that in terms of From all the study it is clear that in terms of

collisioncollision domaindomain, each port on a bridge, a , each port on a bridge, a switch or a router is in a separate collision switch or a router is in a separate collision domain. And each port on a hub is in the same domain. And each port on a hub is in the same collision domain.collision domain.

• In terms of In terms of broadcast domainbroadcast domain, all ports on a , all ports on a hub or a switch are in the same broadcast hub or a switch are in the same broadcast domain. And all ports on a router are in a domain. And all ports on a router are in a different broadcast domain, means for each different broadcast domain, means for each port of a router there will be a separate port of a router there will be a separate broadcast domain.broadcast domain.

Final ExampleFinal Example

QuestionQuestion• Why Hubs work at Layer 1 (Physical Layer) while Why Hubs work at Layer 1 (Physical Layer) while

other devices like Bridges, Switches and Routers other devices like Bridges, Switches and Routers work at Layer 2 (Data Link Layer) & Layer 3 work at Layer 2 (Data Link Layer) & Layer 3 (Network Layer)?(Network Layer)?

• Hubs do not use any part of the packet header to direct Hubs do not use any part of the packet header to direct the packet to the right destination, it broadcasts the data the packet to the right destination, it broadcasts the data to all the attached nodes. At physical layer, the data is in to all the attached nodes. At physical layer, the data is in the form of bits means there is no frame headers or the form of bits means there is no frame headers or packet headers. Hub works at Layer 1 because it does not packet headers. Hub works at Layer 1 because it does not need any header addresses as it broadcasts the data to need any header addresses as it broadcasts the data to all the attached nodes.all the attached nodes.

• While the other devices (Bridges, Switches and Routers) While the other devices (Bridges, Switches and Routers) are are intelligent devicesintelligent devices. They send data to the specific . They send data to the specific destination that is why they need packet headers to get destination that is why they need packet headers to get the right destination address. They work at Layer 2 and 3 the right destination address. They work at Layer 2 and 3 where data is in the form of frames and packets. where data is in the form of frames and packets.

FirewallFirewall

• May be May be HardwareHardware or or SoftwareSoftware

• All the traffic coming into network has to pass All the traffic coming into network has to pass through the firewallthrough the firewall

• Used to prevent some traffic to come into the Used to prevent some traffic to come into the networknetwork– According to network policyAccording to network policy

• May be used in other wayMay be used in other way– To restrict some specific type of traffic to go out of networkTo restrict some specific type of traffic to go out of network

FirewallFirewall

ProxyProxy• A S/W which acts as a middleware, receiving requests A S/W which acts as a middleware, receiving requests

from clients who want to use some resources hosted on from clients who want to use some resources hosted on some other servers that are accessible through proxysome other servers that are accessible through proxy

• Processing of ProxyProcessing of Proxy– Client connects to proxyClient connects to proxy– Request some service hosted on another serverRequest some service hosted on another server

• File, webpage etc.File, webpage etc.

– Proxy evaluates requestProxy evaluates request– Proxy connects to server to get required servicesProxy connects to server to get required services

• Uses its own name instead of real clientUses its own name instead of real client

– May provide services locally without contacting desired serverMay provide services locally without contacting desired server