For the courtesy of others…

1. For the courtesy of others… • Cell phones may be put on vibrate mode, but please take the call outside of the room.

2. LAN, WAN, Internetworks • Local Area Network (LAN) - An individual network administered by a single organization , usually spans a single geographical area. • Wide Area Network(WAN)- Individual organizations usually lease connections through a telecommunications service provider (TSP) . • T1, DS3, OC3 • PPP, HDLC • Frame Relay, ATM • ISDN, POTS

3. Communication starts with a an application Today’s popular communication tools 1- Instant Messaging A real-time communication by typing text. Developed from earlier Internet Relay Chat (IRC) services . Incorporates features such as: file transfer, voice ,video communication (web cam), chat .

4. Email Message Data Data Data Data Data Protocol Data Units and Encapsulation – another example Segmentation and Encapsulation Header Header Data Header Trailer 0010100111011001010000011111010100010101

5. Email Message Data Data Data Data Data Data Protocol Data Units and Encapsulation Decapsulation and Reassembly Data Header Header Header Trailer 0010100111011001010000011111010100010101

6. 2. NIC generates signals that represent these bits. 3. Passed among LAN devices. 4. Exit the local area (router). Putting It all Together 1. Converted to Binary.

7. 6. Passed among local devices at the destination. Putting It all Together 7. The destination device converts the bits into human readable form.

8. IP Addresses – First look Network Address 172.16.0.0 172.16.10.100/16 Network Address 192.168.1.0/30 172.16.10.55/16 ISP Internet 192.168.1.2/30 172.16.1.1/16 192.168.1.1/30 172.16.10.3/16 C:\> ipconfig Windows IP Configuration Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : IP Address. . . . . . . . . . . . : 172.16.10.100 Subnet Mask . . . . . . . . . . . : 255.255.0.0 Default Gateway . . . . . . . . . : 172.16.1.1

9. Routing Each host contain a routing table that contains at the minimum a “gateway”. The router also needs a routing table that defines where to forward the packet next. This is called the next-hop address or default route. Network device use the Default gateway to send the data toevery device on the Internet it doesn’t know its addresses.

10. 3 www.cisco.com = 198.133.219.25 Domain Name System (DNS) 1 2 www.cisco.com • DNS and the Browser: • The resolver sends the DNS request to the DNS Server. • The server then searches its records and resolves the name with to a corresponding IP Address.

11. Domain Name System (DNS) • The resolver send requeststo the DNS server identified in the configuration • From the IP configuration on the device. • IP Address 192.168.25.25 • Subnet Mask 255.255.255.0 • Default Gateway 192.168.25.1 • DNS Server 208.67.222.222

12. Name Resolution DNS queries are two types of queries: Recursive queries • Queries performed by Host to Local DNS Server Iterative queries • Queries performed Local DNS server to other servers Need the IP address

13. Domain Name System (DNS) • Utility - nslookup: • Windows operating systems provide the nslookup utility. • Use to query a domain name and get the IP Address.

14. Components of the Network Devices (hardware) : End devices or intermediate devices. Media : Wired or wireless media. Services (software) :Network applications, routing protocols, processes, algorithms End devices

15. Source Address Destination Address 107.16.4.21 209.67.102.55 • Each host is identified by two addresses. • IP (Internet Protocol) address and a MAC address (later). • The address of the destination host is used to specify where the message should be sent.

16. Network Representations Network Interface Card (NIC)or LAN adapter : Provides the physical connection to the network for the host device. The media connecting the PC to the networking device plugs directly into the NIC.

17. Two Address Types • Each device has two addresses. • A burned in Layer 2 / MAC address: • A logical , Layer 3 / Network “protocol” Address: • This might be assigned statically or dynamically using DHCP.

18. DHCP • DHCP Information can include: • IP address. • Subnet mask. • Default gateway. • Domain name. • DNS Server. • DHCP servers can be: • Server on LAN. • Router. • Server at ISP “Accessed remotely on t he WAN.

19. IP Packets: Carrying Data End to End • Host X sends a packet to Host Y. • Remember:Two addresses are needed to move a packet from the source to the destination. • MAC Address • IP Address

20. Media The medium provides the channel over which the messages travel from source to destination. Metallic wires within cables Glass or plastic fibers Wireless Transmission

21. Media Coaxial cable and connectors • Central conductor. • Insulation. • Copper braid acting as return path for current and also as shield against interference (noise). • Outer jacket. • Used formerly in Token LANs – died out as UTP was cheaper and gave higher speeds.

22. Standards and Implementation Ethernet 802.3

23. Unshielded twisted pair (UTP) cable Eight wires twisted together into four pairs and with an outer jacket. Jackets protects copper from physical damage. Commonly used for Ethernet LANs. The number of twists per metre is carefully controlled. (Protect from interference)

24. Straight through cable Crossover cable • Wire 1 swaps with 3 • Wire 2 swaps with 6 • Connect similar devices to each other • Connect PC to router , switches to hubs , DTE to DTE or DCE to DCE. Both ends the same Connect PC to switch or hub Connect router to switch or hub Installed cabling is straight through. Connects unlike devices DCE-DTE.

25. Rollover cable Cisco proprietary. Wire order completely reversed. Console connection from PC serial port to router – to configure router. Special cable or RJ45 to D9 adaptor.

26. Cabling – Show the straight-through and cross-over cables Straight-through cable Cross-over cable router switch switch hub hub hub hub hub hub

27. Intermediary Devices switch or hub switch or hub routers LAN WAN Processes running on the intermediary network devices perform these functions: • Regenerate and retransmit data signals. • Determine all network path ways available. • Network address translation. • Permit or deny and manage the flow of data, based on security settings.

28. Serial 0 Routers 192.168.10.1 255.255.255.252 • Used to link networks together. • Routes packets to the best pathbased on Layer 3 IP Destination Address. • Each routers interface is connected to a different network and has an IP address/mask as a gateway for that network users. 172.16.1.1 255.255.255.0 MAC: 0cddeeffaabb Ethernet0 172.16.2.1 255.255.255.0 MAC: 0abbccddeeff Ethernet 1 Each interface has an IP address/mask on it’s network.

29. Choice of router Expandability – Fixed or modular interfaces ? Media – serial , UTP or fibre optic ports ? how many ports of each? Operating System Features – what do you want the router to do? Will you have enough memory to upgrade the operating system? Do you need security supported IOS , VOIP,QOS.

30. Packet Forwarding Routing is done packet-by-packetbased on thedestination IP address.

31. Destination Network Next Hop Metric Routing – First Look Network 192.168.1.0/24 Routers know about routes either statically or dynamically using a routing protocol: • Directly connected networks (C): • Network addresses of its interfaces • Remote networks : learned by static or dynamic Routing Protocol (R = RIP) Network 192.168.2.0/24 192.168.1.254/24 C 192.168.2.0/24 is direction connected, FastEthernet0/1

32. Destination Network - Routing Table Entries • The default route in a routing table performs as a default gateway in a PC. • If a route for a packet cannot be found in the routing table, and a default route is present, that route will be used to forward the packet. • A next-hop is the address of the device that will process the packet next.

33. IP Address 10.1.2.2 is on network 10.1.2.0 Packet Forwarding: Route Found Data for Host 10.1.2.2 / 24 Network 10.1.1.0 Network 10.1.2.0

34. IP Address 207.1.1.1 is on network 207.1.1.0 Packet Forwarding: Default Route Data for Host 207.1.1.1 / 24 Network 10.1.1.0 Network 10.1.2.0

35. IP Address 207.1.1.1 is on network 207.1.1.0 Packet Forwarding: Route Not Found ? Data for Host 207.1.1.1 / 24 Network 10.1.1.0 Network 10.1.2.0

36. Private IP Addresses • RFC 1918 • 10.0.0.0 to 10.255.255.255 (10.0.0.0 /8) • 172.16.0.0 to 172.31.255.255 (172.16.0.0 /12) • 192.168.0.0 to 192.168.255.255 (192.168.0.0 /16) • Need NAT/PAT if it requires to access the internet (next). • These addresses should not be routed in the Internet “Should be blocked by your ISP.

37. Data communications equipment and Data terminal equipment • Data Communications Equipment (DCE) – is a device that supplies the clocking services to another device. The clocking service is needed in WAN to synchronize the transmitted signal. Typically, this device is at the WAN provider end of the link. • Data Terminal Equipment (DTE) – is device that receives clocking services from another device . This device is at the WAN customer or user end of the link. • A router is by default a DTE device . Nevertheless, it can be configured to be a DCE by assigning a clock rate to the router.

38. The purpose of Cisco IOS Software As with a computer, a router or switch or other Cisco devices cannot function without an operating system “IOS:. Cisco “IOS” Internetwork Operating System is stored in the flash memory but can be over written”. The IOS is copied into RAM to run from there when the device is powered on . This function increases the performance of the device. The IOS can be accessed using http or command line interface.

39. Router internal components Similar to PC • Buses • Interfaces • Power Supply • CPU • Memory • RAM • Flash • NVRAM • Rom

40. Router storage areas • NVRAM • Keeps contents • Holds startup configuration file • RAM • Volatile • Holds runnningconfig, tables, queues etc ROM Permanent. Holds POST, boot instructions, basic IOS. Flash Keeps contents Holds one or more IOS images

41. Initial startup of Cisco routers When a Cisco router powers up, it performs a power-on self test (POST). During this self test, the router executes diagnostics from ROM on all hardware modules. After the POST, the following events occur as the router initializes:

42. Configuring the RouterRollover cable – Console interface Used to initially configure and troubleshoot a router. Our rollover cables a DB9 connector at one end and do not need an adaptor.

43. Hyper terminal Match serial port on PC • Set up the PC’s serial port as follows: • Bits per second: 9600 bps • Data bits: 8 • Parity: None • Stop bits: 1 • Flow control: None

44. Backing Up Configuration Files – Capture Text Using Hyper Terminal

45. Examining the initial router bootup

46. Configuring the Router remotely - AUX Auxiliary (AUX) Interface: Used for remote management of a Cisco router. Typically, a modem is connected to the AUX interface for dial-in access.

47. Telnet • Used to remotely access and configure a device (host, router, switch). • To configure a remote router , it should have an active interface with an (IP address). • A connection using Telnet is called a Virtual Terminal (VTY) session, or connection. • Telnet access devices using the command line interface (CLI). • Configuring routers using Telnet should be protected through authentication. Telnet Server Telnet

48. Power-up the router (and switch) – No configuration If the routers do not have a saved configuration. After several lines of information on the screen you should eventually see: Would you like to enter the initial configuration dialog? [yes/no]: n Always answer “n” fo no. We will never be using setup mode. If you accidentally press “y” and enter Setup Mode, press and hold down the control key and press C (CTRL-C). Wait a few seconds, and then press Enter. On some routers you may see the following message. Would you like to terminate autoinstall? [yes/no]: y <There will be several lines of output> Router>

49. Configuration Files • The configuration that defines the desired functionality of a Cisco device. • Two types of configuration files: • Start up configuration : • Stored in the Non-Volatile RAM (NVRAM) . • Used as the backup configuration . • If configured , it is loaded to the RAM as the router boots or reloads o be running configuration . • Running configuration • Changes in running config will be parsed (translated , executed and take effect) by the Cisco IOS immediately or as the system boots. • Should be saved to be included in the startup – config. • A configuration file may also be stored remotely on a server as a backup.

50. The CLI uses a hierarchical structure for the modes. The mode is identified by the prompt that is unique to that mode. Each mode is used to accomplish particular tasks and has a specific set of commands that are available when in that mode.