Bellevue University CIS 341A Mid-Term Review

The exam Monday, June 30, at 6 PM 35 Question multiple choice, True/False, and fill in the blanks You have 70 minutes to complete the exam The exam will be closed book, closed notes, closed communication between students

Scoring 2.8 points for each correct answer 2 points for putting your name on your paper and turning it in If the entire class gets a question wrong, it will be thrown out and 2.8 points will be credited to each student

What to study The review slides The Reading Assignments The Lab Assignments The Quizzes

What the exam will cover Internetworking Internet Protocols IP Subnetting and Variable Length Subnet Masks (VLSMs) Introduction to the Cisco IOS IP Routing

Internetworking Basics A network consists of two or more hosts connected by a common communications medium for the purpose of sharing information. An internetwork consists of two or more networks connected by routers.

Internetworking Basics In Ethernet twisted pair networks, switches are typically used to connect hosts together. In internetworks routers are used to connect networks together.

Switches and Routers Layer 2 switches break up collision domains Layer 3 switches and routers break up broadcast domains

The OSI Model 7 layer abstract network model Simplifies design and interaction of protocols Provides a framework for the study of protocols

The OSI Reference Model OSI Reference Model’s Seven Layers –Application Layer –Presentation Layer –Session Layer –Transport Layer –Network Layer –Data Link Layer –Physical Layer

The OSI Reference Model Application Layer: File, print, message, database and application services. Presentation Layer: Data encryption, compression and translation services. Session Layer: Dialog control. OSI Reference Model’s Seven Layers and Functions Transport Layer: End-to-end connection. Network Layer: Routing. Data Link Layer: Framing. Physical Layer: Physical topology.

The OSI Reference Model The Transport Layer The address used in the transport layer is the port number There are two protocols that operate at this layer: Transmission Control Protocol and User Datagram Protocol Each protocol has its own set of ports

The OSI Reference Model The address used in the Network layer is the IP Address A protocol number is also used to determine what protocol to deliver the packet to at the destination. The Network Layer

The OSI Reference Model The Data Link Layer The address used in the data link layer is the physical address (also known as hardware or MAC address.

The OSI Reference Model The Physical Layer Sends and receives bits; 1’s & 0’s Specify electrical, mechanical, procedural, and functional requirements DTE/DCE interfaces identified Hubs (Multi-port repeaters)

Ethernet Networking A connection media access method that allows all hosts on a network to share the same bandwidth (Uses Data Link & Physical Layer specifications) CSMA/CD Half Duplex Full Duplex

Ethernet at the Data Link Layer Ethernet addressing = Hardware or MAC Framing –Types of Ethernet frames: Ethernet II IEEE IEEE SNAP Ethernet Networking

Ethernet Frames

Ethernet Cabling Unshielded twisted pair Coax Fiber

Connecting devices together Use these guidelines when cabling between ports: 1.Use straight through cables when connecting unlike devices together 2.Use crossover cables when connecting like devices together

Wireless Networking

Wireless Network Types Narrowband Wireless LANs Personal Communication Services (PCS) Narrowband PCS Broadband PCS Satellite Infrared Wireless LANs Spread Spectrum Wireless LANs

Data Encapsulation

TCP/IP and the DoD Model

The TCP/IP Protocol Suite TCP/IP and the DoD Model

Host-to-Host Layer Protocols TCP/IP and the DoD Model Transmission Control Protocol (TCP)

Host-to-Host Layer Protocols TCP/IP and the DoD Model User Datagram Protocol (UDP)

Key Concepts of Host-to-Host Protocols TCP/IP and the DoD Model

Port Numbers < 1024: “Well-known port numbers” –Defined in RFC 3232; linked to specific applications or protocols 1024: Dynamically assigned –Used by upper layers to communicate between hosts TCP/IP and the DoD Model

Internet Layer Protocols Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) TCP/IP and the DoD Model

Internet Layer Protocols TCP/IP and the DoD Model

Internet Layer Protocols TCP/IP and the DoD Model

Internet Layer Protocols TCP/IP and the DoD Model

Local ARP Broadcast TCP/IP and the DoD Model

RARP Broadcast TCP/IP and the DoD Model

Binary to Decimal and Hexadecimal Conversion

IP Addressing The Hierarchical IP Addressing Scheme Dotted-decimal, as in Binary, as in Hexadecimal, as in AC.10.1E.38

Summary of the Three Classes of Networks IP Addressing

Reserved IP Addresses IP Addressing

Classful Routing The class of an IP address is determined by its most significant bits. 0 Class A 10 Class B 110 Class C 1110 Class D 1111 Class E

IP Addresses Class A – through Class B – through Class C – through Class D – through Class E – through

Classful Routing Only Class A, B, and C addresses are routable through the Internet.

Class A Addresses Structure –Network –Network.node.node.node Class A Valid Host IDs – All host bits off – All host bits on –Valid hosts = ’s & 255s are valid hosts but hosts bits cannot all be off or on at the same time! = 2 22 IP Addressing

Class B Addresses Structure –NetworkNetwork –Network.Network.node.node Class B Valid Host IDs – All host bits off – All host bits on –Valid hosts = ’s & 255s are valid hosts but hosts bits cannot all be off or on at the same time! = 2 14 IP Addressing

Class C Addresses Structure –NetworkNetworkNetwork –Network.Network.Network.node Class C Valid Host IDs – All host bits off – All host bits on –Valid hosts = ’s & 255s are valid hosts but hosts bits cannot all be off or on at the same time! = 2 6 IP Addressing

Private IP Addresses IP Addressing

Broadcast Addresses

Subnetting Basics Benefits of subnetting include: –Reduced network traffic –Optimized network performance –Simplified management –Facilitated spanning of large geographical distances.

Subnet Mask A 32-bit binary number that determines what part of an IP address is the network part and what part is the host part.

Default Subnet Masks

Classless Inter-Domain Routing (CIDR) Used to allocate an amount of IP address space to a given entity (company, home, customer, etc). Example: /28 The slash notation (/) means how many bits are turned on (1s) and tells you what your subnet mask is.

CIDR Values

Subnetting Class C Addresses

Subnetting Class C Addresses – Binary Method

Subnetting Class C Address – Binary Method (cont.)

How Many Subnets? 2 x -2 = number of subnets. –X is the number of masked bits, or the 1s. –For example, in , the number of ones gives us subnets. In this example there are 2 subnets.

How Many Hosts Per Subnet? 2 y -2 = number of hosts per subnet. –Y is the number of unmasked bits, or the 0s. –For example, in , the number of zeros gives us hosts. In this example, there are 62 hosts per subnet.

What Are The Valid Subnets? 256-subnet mask = block size, or base number. For example = is the first subnet. The next subnet would be the base number plus itself or 64+64=128, (the second subnet).

What’s The Broadcast Address For Each Subnet? The broadcast address is all host bits turned on, which is the number immediately preceding the next subnet.

What Are The Valid Hosts? Valid hosts are the number between the subnets, omitting all 0s and all 1s.

Subnets with no VLSM applied

Subnets with VLSM applied

Implementing VLSM Networks

Four Immutable Laws The lowest numbered address in a range of IP addresses that constitute a subnet is the network address. This address cannot be assigned to a host. The highest numbered address in a range of IP addresses that constitute a subnet is the broadcast address. This address cannot be assigned to a host. For any IP address in a range of IP addresses that constitute a subnet, the network part of the IP address must be identical. For any IP address in a range of IP addresses that constitute a subnet, the host part of the IP address must be unique.

Cisco Router IOS Carries network protocols and functions Connects high-speed traffic between devices Adds security to control access Provides scalability for growth Supplies reliability

Bringing up a Router Boot-up process: 1: POST 2: Looks for the Cisco IOS from Flash memory 3: IOS loads & looks for a valid configuration; startup-configstartup-config stored in nonvolatile RAM (NVRAM) 4: If a valid config is not found in NVRAM: setup modesetup mode

Setup Mode Basic Management Setup Extended Setup Command-Line Interface

Command-Line Interface (CLI) More flexible than setup mode. To use the CLI, just say No to entering the initial configuration dialog.

Logging into the Router User mode: –Router> –Used mostly to view statistics Privileged mode: –Router# –Used to view & change router configuration

Overview of Router Modes Global changes: –config terminal or config t running-config –Changes made to running-config (DRAM) startup-config –To change the startup-config (NVRAM) config memory or config mem running-config Note: Any configuration changes need to be placed into RAM. Typing config mem or config net (from a TFTP host) will replace the current running-config

Configuration CLI Prompts Interfaces Sub-interfaces Line Commands Routing Protocol Configurations

Editing & Help Features Commands starting with a certain letter Router#c? clear clock configure connect copy Enhanced Editing Commands Router-Command History Gathering Basic Routing Information –show version

Setting the Passwords 5 passwords: –1st two used to set your enable password Used to secure privileged mode; Router>enable user –Other three are used to configure a password in user mode via: console port auxiliary port Telnet

Passwords Enable passwords Router(config)#enable password cisco Router(config)#enable secret cisco Auxiliary Password Console Password Telnet Password Encrypting Your Password Router(config)#service password-encryption

Banners Purpose Types –exec –incoming –login –motd Delimiting character

Router Interfaces Purpose Bringing up an Interface no shutdown shutdown show interface Configuring an IP Address on an Interface Router(config)#int e0 Router(config-if)#ip address Router(config-if)#no shut Serial Interface Commands clock rate & bandwidth (entered in kilobits)

Hostnames & Descriptions Hostnames Router(config)#hostname todd todd(config)# Descriptions Atlanta(config)#int e0 Atlanta(config-if)#description Sales Lan

Viewing, & Saving Configurations Viewing & Saving Configurations –running-config –running-config saved in DRAM –startup-config –startup-config saved in NVRAM copy run start sh run sh start erase startup-config

Verifying Your Configuration Tools: show running-config show startup-config ping show cdp nei detail trace telnet

Other Verification Methods Verifying with the show interface command –Router#show interface ? Verifying with the show ip interface command –Router#show ip interface –Router#show ip interface brief –Router#show controllers

Routing Definition –Routing protocol –Routed protocol What must routers know?

IP Routing in Our Network Routing tables Routing protocols Types of routing –Static –Default –Dynamic

Routing Table Converts the destination address in a packet header to the IP address of the next link. The address of the next link is converted to the hardware address of the next link by arp.

Routing Protocols A routing protocol is used to dynamically update a routing table. It uses information from other routers to add, modify, or delete routes in its own table.

IP Routing Process (cont.)

Static Routing Definition Benefits Disadvantages Adding a static route: ip route [destination_network] [mask] [next_hop_address or exitinterface] [administrative_distance] [permanent]

Default Routing Definition – Default routing is routing traffic based on the destination IP not matching any entries in the routing table. Configuration – A default route is configured as the last route in the table. Any destination IP that doesn’t match any entries in the table will use the default route.

Dynamic Routing Definition: Dynamic routing is a process by which routes are automatically added, modified, or deleted based on information received from other routers. Types of Routing Protocols –Routing Information Protocol (RIP) –Open Shortest Path First (OSPF) –Interior Gateway Protocol (IGP) –Enhanced Interior Gateway Protocol (EIGRP) –Exterior Gateway Protocol (EGP)

Classes of Routing Protocols Classes –Distance Vector –Link State –Hybrid

Stopping Routing Loops Maximum Hop Count – A route is removed from the routing table if its hop count exceeds a preset value (RIP – 15 hops, IGRP – 255 hops). Split Horizon – prevents the router from advertising a route that goes back to itself. Route Poisoning – a router advertises a route then marks it unreachable. Holddowns – Keeps a router from announcing a route change until a certain amount of time has elapsed.

Routing Information Protocol (RIP) A true distance-vector protocol –Sends updates every 30 seconds on all active interfaces –Only uses hop count Maximum allowable hop count of 15 Good for small networks –Inefficient on large networks or slow WAN links

RIP RIP Timers –Route update timer – how much time to wait between updates –Route timeout timer – how much time to wait before marking a route as invalid –Route flush timer – how much time to wait before flushing a route

Interior Gateway Routing Protocol (IGRP) Definition Cisco proprietary distance vector routing protocol that uses multiple metrics to determine dynamic routes. IGRP Timers –prevent “route flapping” –Update timers – specifies how frequently update messages should be sent –Invalid timers – how long a router should wait before declaring a route as invalid –Holddown timers - how much time to wait before sending an update message –Flush timers – how much time to wait before removing a route