The Saigon CTT Semester 1 CHAPTER 11 Le Chi Trung.

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Semester 1Semester 1

CHAPTER 11CHAPTER 11

Le Chi TrungLe Chi Trung

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ContentContent

• Layer 3 Devices

• ARP concept

• Network layer services

• Routed and routing protocols

• Protocol analyzer

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ScheduleSchedule

No Name Est time No Name23-Jun Chapter 10 Online Exam

11.1 Layer 3 devices 0:30:0011.2 Network-to-Network communications 0:30:00

26-Jun 11.3 Advanced ARP concepts 0:20:0011.4 Routable protocols 0:20:0011.5 Routing protocols 0:20:0011.6 Other network layer services 0:20:0011.7 ARP tables 0:20:0011.8 IGP and EGP 0:20:00

28-Jun 11.9 Protocol analizer software 0:30:0011.9.1 Protocol Inspector and ARP

Summary Chapter 11 0:30:0003-Jul Chapter 11 Online Exam

DayLesson Lab

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LAYER 3 DEVICESLAYER 3 DEVICES

ANDAND

NETWORK TO NETWORK NETWORK TO NETWORK

COMMUNICATIONCOMMUNICATION

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InternetworkingInternetworking

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Path determinationPath determination

• Path determination is the process that the router uses to choose the next hop in the path for the packet to travel to its destination based on the link bandwidth, hop, delay ...

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RouterRouter

• A router is a type of internetworking device that passes data packets between networks, based on Layer 3 addresses.

• A router has the ability to make intelligent decisions regarding the best path for delivery of data on the network.

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IP addressesIP addresses

• IP addresses are implemented in software, and refer to the network on which a device is located.

• IP addressing scheme, according to their geographical location, department, or floor within a building.

• Because they are implemented in software, IP addresses are fairly easy to change.

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Router and BridgeRouter and Bridge

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Router connectionsRouter connections

• Routers connect two or more networks, each of which must have a unique network number in order for routing to be successful.

• The unique network number is incorporated into the IP address that is assigned to each device attached to that network.

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Router InterfaceRouter Interface

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Router functionRouter function

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Router function (cont.1)Router function (cont.1)

Strips off the data link header, carried by the frame.

(The data link header contains the MAC addresses of the source and destination.)

Strips off the data link header, carried by the frame.

(The data link header contains the MAC addresses of the source and destination.)

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Examines the network layer address to determine the destination network.

Examines the network layer address to determine the destination network.

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Consults its routing tables to determine which of its interfaces it will use to send the data, in order for it to reach its destination network.

Consults its routing tables to determine which of its interfaces it will use to send the data, in order for it to reach its destination network.

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Send the data out interface B1, the router would encapsulate the data in the appropriate data link frame.

Send the data out interface B1, the router would encapsulate the data in the appropriate data link frame.

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Router Interface exampleRouter Interface example

• Interface is a router’s attachment to a network, it may also be referred to as a port. In IP routing.

• Each interface must have a separate, unique network address.

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IP address assignmentIP address assignment

static addressing and dynamic addressing

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Static addressingStatic addressing

• You must go to each individual device and configure it with an IP address.

• You should keep very meticulous records, because problems can occur on the network if you use duplicate IP addresses.

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Dynamic addressingDynamic addressing

• There are a few different methods that you can use to assign IP addresses dynamically:

– RARP: Reverse Address Resolution Protocol.

– BOOTP: BOOTstrap Protocol.

– DHCP: Dynamic Host Configuration Protocol.

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Dynamic addressing:Dynamic addressing: RARP RARP

MAC:MAC: KnownKnownIP: IP: UnknownUnknown


RARP RequestRARP Request

RARP ReplyRARP Reply

RARP serverRARP server

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Dynamic addressing:Dynamic addressing: BOOTP BOOTP



UDP BroadcastUDP Broadcast

UDP BroadcastUDP Broadcast

BOOTP serverBOOTP server

MACMAC11 – IP – IP11MACMAC22 – IP – IP22MACMAC33 – IP – IP33

MACMAC11 – IP – IP11MACMAC22 – IP – IP22MACMAC33 – IP – IP33

IP AddressIP AddressGatewayGatewayIP of serverIP of serverVendor-specificVendor-specific

IP AddressIP AddressGatewayGatewayIP of serverIP of serverVendor-specificVendor-specific

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Dynamic addressing:Dynamic addressing: DHCP DHCP



DHCP DiscoverDHCP DiscoverUDP BroadcastUDP Broadcast

DHCP OfferDHCP OfferUDP BroadcastUDP Broadcast

DHCP serverDHCP server

IPIP11IPIP22IPIP33

IPIP11IPIP22IPIP33

DHCP RequestDHCP Request

DHCP AckDHCP Ack

IP AddressIP AddressGatewayGatewayIP of serversIP of serversAnd more …And more …

IP AddressIP AddressGatewayGatewayIP of serversIP of serversAnd more …And more …

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ReviewReview

• The role of router in network.

• Address assignment.

• Static addressing.

• Dynamic addressing.

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ARP CONCEPTARP CONCEPT

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EncapsulationEncapsulation

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Address resolution protocolAddress resolution protocol

• In order for devices to communicate, the sending devices need both the IP addresses and the MAC addresses of the destination devices.

• When they try to communicate with devices whose IP addresses they know, they must determine the MAC addresses.

• ARP enables a computer to find the MAC address of the computer that is associated with an IP address.

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Address resolution protocolAddress resolution protocol

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ARP table in hostARP table in host

RAMRAM

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10.0.2.1A.B.C.1.2.3

10.0.2.9A.B.C.7.8.9

10.0.2.5A.B.C.4.5.6

AA BB CC

ARP operationARP operation

ARP Table:

? MAC A.B.C.1.2.3

MAC

?IP

10.0.2.1IP

10.0.2.9Data

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10.0.2.1A.B.C.1.2.3

10.0.2.9A.B.C.7.8.9

10.0.2.5A.B.C.4.5.6

AA BB CC

ARP operation:ARP operation: ARP request ARP request

MAC A.B.C.1.2.3

MACff.ff.ff.ff.ff.ff

IP10.0.2.1

IP10.0.2.9

What is your MAC Addr?

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10.0.2.1A.B.C.1.2.3

10.0.2.9A.B.C.7.8.9

10.0.2.5A.B.C.4.5.6

AA BB CC

ARP operation:ARP operation: Checking Checking

MAC A.B.C.1.2.3

MACff.ff.ff.ff.ff.ff

IP10.0.2.1

IP10.0.2.9

What is your MAC Addr?

That

is

That

is

my

IPm

y IP

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10.0.2.1A.B.C.1.2.3

10.0.2.9A.B.C.7.8.9

10.0.2.5A.B.C.4.5.6

AA BB CC

ARP operation:ARP operation: ARP reply ARP reply

MAC A.B.C.7.8.9

MACA.B.C.1.2.3

IP10.0.2.9

IP10.0.2.1

This is my MAC Addr

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10.0.2.1A.B.C.1.2.3

10.0.2.9A.B.C.7.8.9

10.0.2.5A.B.C.4.5.6

AA BB CC

ARP operation:ARP operation: Caching Caching

ARP Table:

A.B.C.7.8.9 – 10.0.2.9

MAC A.B.C.1.2.3

MACA.B.C.7.8.9

IP10.0.2.1

IP10.0.2.9

Data

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ARP:ARP: Destination local Destination local

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Internetwork communicationInternetwork communication

• How to communicate with devices that are not on the same physical network segment.

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Default gatewayDefault gateway

• In order for a device to communicate with another device on another network, you must supply it with a default gateway.

• A default gateway is the IP address of the interface on the router that connects to the network segment on which the source host is located.

• In order for a device to send data to the address of a device that is on another network segment, the source device sends the data to a default gateway.

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Proxy ARPProxy ARP

• Proxy ARP is a variation of the ARP.

• In the case the source host does not have a default gateway configured.

ARP Reply

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ARP:ARP: Destination not local Destination not local

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ARP FlowchartARP Flowchart

Send Data to a device

Send Data

Send anARP request

Get anARP reply

Is the MAC address

in my ARP cache

NN

YY

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Flowchart: Flowchart: ExercisesExercises

• Create flowcharts for the following processes:

– RARP

– BOOTP

– DHCP

– Proxy ARP (in router)

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ARP table in routerARP table in router

• The router interface connected to the network has an IP address for that network.

• Routers, just like every other device on the network, send and receive data on the network.

• If router connects to a LAN, it builds ARP tables that maps IP addresses to MAC addresses in that interface.

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ARP table in routers and in hostsARP table in routers and in hosts

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ReviewReview

• What is the purpose of ARP protocol?

• How does ARP protocol work?

• What is the role of default gateway?

• What is proxy ARP?

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NETWORK LAYER SERVICESNETWORK LAYER SERVICES

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Connection oriented network servicesConnection oriented network services

• A connection is established between the sender and the recipient before any data is transferred.

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Circuit switchedCircuit switched

• Connection-oriented network processes are often referred to as circuit switched.

• These processes establish a connection with the recipient, first, and then begin the data transfer.

• All packets travel sequentially across the same physical circuit, or more commonly, across the same virtual circuit.

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Connectionless network servicesConnectionless network services

• They treat each packet separately.

• IP is a connectionless system.

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Packet switchedPacket switched

• Connectionless network processes are often referred to as packet switched.

• When the packets pass from source to destination, they can:– Switch to different paths.

– Arrive out of order.

• Devices make the path determination for each packet based on a variety of criteria. Some of the criteria may differ from packet to packet.

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ReviewReview

• Comparing connectionless and connection-oriented services.

• IP is a connectionless system.

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ROUTED AND ROUTING PROTOCOLSROUTED AND ROUTING PROTOCOLS

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Network protocolsNetwork protocols

• In order to allow two host communicate together through internetwork, they need a same network protocol.

• Protocols are like languages. • IP is a network layer protocol.

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Network protocol operationNetwork protocol operation

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Routed protocolRouted protocol

• Protocols that provide support for the network layer are called routed or routable protocols.

• IP is a network layer protocol, and because of that, it can be routed over an internetwork.

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Protocol addressing variationsProtocol addressing variations

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Three important routed protocolsThree important routed protocols

• TCP/IP: 04 bytes

– Class A: 1 byte network + 3 bytes host

– Class B: 2 bytes network + 2 bytes host

– Class C: 3 bytes network + 1 byte host

• IPX/SPX: 10 bytes

– 4 bytes network + 6 bytes host

• AppleTalk: 03 bytes

– 2 bytes network + 1 byte host

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Non-routable protocolNon-routable protocol

• Non-routable protocols are protocols that do not support Layer 3.

• The most common of these non-routable protocols is NetBEUI.

• NetBEUI is a small, fast, and efficient protocol that is limited to running on one segment.

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Addressing of a routable protocolAddressing of a routable protocol

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Routing tableRouting table

131.108.1.0 E0

131.108.2.0 E1

131.108.3.0 E2

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Multi-protocol routingMulti-protocol routing

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Classification #1:Classification #1: Static and Dynamic Static and Dynamic

• Static routes:

– The network administrator manually enter the routing information in the router.

• Dynamic routes:

– Routers can learn the information from each other on the fly.

– Using routing protocol to update routing information.

– RIP, IGRP, EIGRP, OSPF …

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Static routesStatic routes

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Dynamic routesDynamic routes

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Static vs. dynamic routesStatic vs. dynamic routes

• Static routes:

– For hiding parts of an internetwork.

– To test a particular link in a network.

– For maintaining routing tables whenever there is only one path to a destination network.

• Dynamic routes:

– Maintenance of routing table.

– Timely distribution of information in the form of routing updates.

– Relies on routing protocol to share knowledge.

– Routers can adjust to changing network conditions.

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Routing protocolRouting protocol

• Routing protocols determine the paths that routed protocols follow to their destinations.

• Routing protocols enable routers that are connected to create a map, internally, of other routers in the network or on the Internet.

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Routed vs. Routing protocolRouted vs. Routing protocol

Routing protocols

Routing protocols

determine how ro

uted

determine how ro

uted

protocols are routed

protocols are routed

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Classification #2:Classification #2: IGP and EGP IGP and EGP

• Dynamic routes.

• Interior Gateway Protocols (RIP, IGRP, EIGRP, OSPF):

– Be used within an autonomous system, a network of routers under one administration, like a corporate network, a school district's network, or a government agency's network.

• Exterior Gateway Protocols (EGP, BGP):

– Be used to route packets between autonomous systems.

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IGPIGP

IGPIGP

IGP vs. EGP IGP vs. EGP

EGPEGP

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Classification #3:Classification #3: DVP and LSP DVP and LSP

• Distance-Vector Protocols (RIP, IGRP):– View network topology from neighbor’s

perspective.

– Add distance vectors from router to router.

– Frequent, periodic updates.

– Pass copy of routing tables to neighbor routers.

• Link State Protocols (OSPF):– Gets common view of entire network topology.

– Calculates the shortest path to other routers.

– Event-triggered updates.

– Passes link state routing updates to other routers.

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Distance vector routingDistance vector routing

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Link state routingLink state routing

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RIP RIP

• Most popular.

• Interior Gateway Protocol.

• Distance Vector Protocol.

• Only metric is number of hops.

• Maximum number of hops is 15.

• Updates every 30 seconds.

• Doesn’t always select fastest path.

• Generates lots of network traffic.

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IGRP and EIGRP IGRP and EIGRP

• Cisco proprietary.


• Distance Vector Protocol.

• Metric is compose of bandwidth, load, delay and reliability.

• Maximum number of hops is 255.

• Updates every 90 seconds.

• EIGRP is an advanced version of IGRP, that is hybrid routing protocol.

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OSPF OSPF

• Open Shortest Path First.


• Link State Protocol.

• Metric is compose of cost, speed, traffic, reliability, and security.

• Event-triggered updates.

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Routing with RIP (11.8.9) Routing with RIP (11.8.9)

Subnet Next Metric

1

2

3

…

ExerciseExercise

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Preparation for LABPreparation for LAB

• Lab companion:

– 11.9.1

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ReviewReview

• Compare routed and routing protocols.

• Classification of routing protocols.

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The Saigon CTT Semester 1 CHAPTER 11 Le Chi Trung.

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Transcript of The Saigon CTT Semester 1 CHAPTER 11 Le Chi Trung.