1. Chapter 6 Intro to Routing & Switching

2.  Upon completion of this chapter, you should be able to:  Describe the purpose of the network layer  Explain why IPv4 uses other layers for reliability  Explain how host devices use routing tables to direct packets  Compare host and router routing tables  Describe components of a router  Describe the boot-up process of a Cisco router  Configure a Cisco router and interfaces  Configure a default gateway

3. 6.1.1

5. 6.1.2

6.  Low overhead  Delivers packet to destination only  Does NOT track or manage flow Other layers handle that  Connectionless  Doesn’t need a connection established w/ dest.  Best effort delivery  Unreliable, no guarantee (other layers)  Media independent  Doesn’t matter which type of cable being used

7.  Uses the upper layer connections- oriented protocol( TCP-UDP) to acknowledge data receipt

8.  If you want to mail a letter…  You put it in on paper (encoding)  Place it in envelope & address it (encapsulation)  How do you get that letter on its way to another house/network? The default gateway, which is your mailbox  You have no idea if or when the letter gets there, or whether the person on the other end can read it  Postal service just delivers it. They don’t know what’s in envelope.  If mail gets lost, no notification, no redelivery.

9.  Doesn’t matter what cables/media it travels over  What layer handles the prep for media?

10.  6.1.2.6  Read each IP characteristic & decide if it describes connectionless, best effort, or media independent.

11.  IP is described as connectionless, or connection-oriented?  Connectionless  When using IP, what protocol would be used to acknowledge delivery of packets and retransmission of missing ones?  TCP  What layer does TCP operate at?  Transport

12. 6.1.3

13.  Includes Header & Payload  Header includes:  Source & destination IP  DS (Differentiated Services) Defines the priority of each packet  Protocol TCP/UDP  TTL (Time-to-Live) Hops until dropped

14. Version, IP’s DS, Total Length, Flags, TTL

15.  Which field in the IPv4 header…  Tells the priority of a packet? DS  Helps with fragmented packets when split to not exceed the MTU on media? Flags  Name a connectionless layer 3 protocol that is popular & in use today?  IP  What helps IP with guaranteed delivery?  TCP

16. 6.1.4

17.  Running out of addresses  Routing tables growing  Lack of end to end connectivity  NAT is normally used NAT allows certain private IP addresses to be used within a network and not shared with the outside world The internal private IP gets translated to a public one to send data across Internet

18. IPv4IPv6  32-bit addresses  4 billion available  Many header fields  Must use NAT  To conserve addresses  128-bit addresses  340 undecillion avail.  Less header fields  Better packet handling  No need for NAT  A lot of IPv6 addresses

20. Version, Payload Length, Hop Limit, IPv6 addresses

21.  Handout to compare IPv4 & 6 headers  6.1.4.6  Read each IPv6 header description & click which field it belongs to.

22.  Explain NAT.  Private internal IP addresses. Can’t be seen outside network. Translate to a public IP for the entire internal network.  Why is NAT not needed with IPv6?  A ton of addresses!  What field in an IPv6 header…  Has routers use the same path for real-time packets? Flow label  Is like the DS field for priority? Traffic Class

23.  Review the picture.  What kind of IP is being used?  IPv4  How many hops from PC1 to PC33? 33

24. 6.2.1

25.  Itself (loopback)  127.0.0.1  Local  Shares same network address  Remote  On a different network

26.  PC has a “mini” routing table

27.  6.2.1.7  Identify the parts of a host routing table

28.  How does a PC know where to send packets?  It has its own routing table  What 2 commands on a PC will view the routing table?  Netstat –r or route print

30. 6.2.2

31.  After packet reaches DG (router), it looks at the routing table to see where to send it.  After matching the destination To directly connected routing table  Switch the packet to the directly connected interface  What’s in the table?  Directly connected routes  Remote routes

33.  Show ip route  Stored in RAM  How it was learned  When it was updated  Which interface to use to get to that network

36. R1#show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks D 10.1.1.0/24 [90/2170112] via 209.165.200.226, 00:00:05, Serial0/0/0 D 10.1.2.0/24 [90/2170112] via 209.165.200.226, 00:00:05, Serial0/0/0 192.168.10.0/24 is variably subnetted, 2 subnets, 3 masks C 192.168.10.0/24 is directly connected, GigabitEthernet0/0 L 192.168.10.1/32 is directly connected, GigabitEthernet0/0 192.168.11.0/24 is variably subnetted, 2 subnets, 3 masks C 192.168.11.0/24 is directly connected, GigabitEthernet0/1 L 192.168.11.1/32 is directly connected, GigabitEthernet0/1 209.165.200.0/24 is variably subnetted, 2 subnets, 3 masks C 209.165.200.224/30 is directly connected, Serial0/0/0 L 209.165.200.225/32 is directly connected, Serial0/0/0 R1# 192.168.10.0/24 R2 192.168.11.0/24 10.1.1.0/24 10.1.2.0/24 209.165.200.224 /30.226.10.1 G0/1.225 S0/0/0 G0/0.1 R1 PC1 PC2

37.  6.2.2.7  Identify the elements of a routing table  Lab 6.2.2.8  Discover your PC’s routing table

38.  A packet comes into the interface of a router. Which address does it check?  Destination IP  What does it then use that address to look at?  Routing table  What happens if a match is found for the destination network?  It sends it out that port towards that destination

39.  What command displays the routing table on a router?  Show ip route  Where is the routing table stored?  RAM  What would happen if a destination network was not in the routing table and there was no default route configured?  Packet is dropped

40. 6.3.1

41.  OS  RAM  CPU  ROM

42. Content in ram is lost if router is suddenly powered off

43. Console Port RJ45 AUX Port RJ45 LAN interfaces WAN Serial Ports in slot LAN Interfaces in slot

44.  6.3.1.8  Match the router interface or function with its description  Lab 6.3.1.9  Explore the router externally & using show commands  Lab 6.3.1.10  Determine connectivity options on a router

45.  Where is the IOS stored?  Flash  Where is the running-config at?  RAM  Where is the startup-config stored?  NVRAM  Where is the limited IOS at?  ROM ( used when full os can not be found)  Where is the routing table stored?  RAM

46.  Based on the last 5 questions, which ones will get “lost” if you lose power to the router & why?  Running-config & routing table because they are in RAM  Which ports on the router will allow out-of-band management?  Console & AUX  If you want to gain access to router configuration remotely through Telnet or SSH, which interfaces would you be “connecting” to?  Ethernet/LAN or Serial/WAN  What 2 things get copied into RAM upon a normal boot?  IOS & startup-config

47. 6.3.2

48.  Similar to PC booting  POST  IOS in flash memory & loads into RAM  Startup-config loads into RAM  Becomes running-config  Changes made to config happen in RAM/running-config  MUST SAVE THEM!

49.  POST tests hardware (CPU, Memory)  ROM: Bootstrap  Boot Image  Begins search for IOS

50.  Locate & load IOS into RAM  Usually in Flash (default) or TFTP Server

51.  Configuration File or Setup  NVRAM (1 st ), TFTP Server (2 nd ), Console (3 rd )  If found, copies into RAM Becomes the running-config  If not found, enters Setup Mode

52.  Show version  IOS version  Version of bootstrap  Location & name of IOS  CPU & RAM  Interfaces  Amount of NVRAM & Flash  Config-register  0x2102

53. Model & IOS version Bootstrap version Amount of RAM Total/Used Amount of RAM Total/Used IOS locale & name Interfaces Amt. of NVRAM Amt. of Flash Amt. of NVRAM Amt. of Flash Config-register

54.  In Packet Tracer…  Add an 1841 router  Go in & answer questions based on show version output on handout  Add a 2960 switch and do the same  6.3.2.6  The router boot process  Put the steps in order

55.  When would a limited version of the IOS load?  If the full IOS can’t be found  What does this mean? Flash0: c1841-universal.152-4.bin  The IOS is in flash & that’s its file name  What happens first when booting a router?  POST  When loading the IOS, where does it look?  Flash, TFTP Server, ROM

57. 6.4.1

58.  Hostname  Passwords  Enable, enable secret, console, vty  Banner motd  Service password-encryption  Save= copy run start  Show run/ show start  Line console 0  Password cisco  login  Complete 6.4.1.1- #5

59.  Lab 6.4.1.2  Configure initial settings

60. 6.4.2

61.  6.4.2.1- #2

62.  Show interfaces  Show ip int brief  Show ip route- routing table

64.  S1(config)#interface vlan1  S1(config-vlan)#ip address 192.168.10.50 255.255.255.0  S1(config-vlan)#no shutdown  6.4.3.2- #2

65.  6.4.3.3 Configuring the Default Gateway  You will use various show commands to display the current state of the router. You will then use the Addressing Table to configure router Ethernet interfaces. Finally, you will use commands to verify and test your configurations.  6.4.3.4 Troubleshooting DG Issues

66.  Build a network or routers and switches

67.  What command saves the config?  Copy run start  What command displays all interface statuses and IP addresses in summary?  Show ip int brief  What command displays router memory, IOS name, and config-register?  Show version  What does your PC need to have configured in order to get out of your network?  Default gateway

68.  When will a packet go through a router?  To go to ANOTHER/DIFFERNET network/lan if destined for it  When configuring an interface, what command turns it on?  No shutdown  2 routers connect with a serial cable. You configured one of their S0/0 interfaces but the link still isn’t working. Why?  Both connected must be configured before it works

69.  Complete the study guide handout  Take the quiz on netacad.com  Jeopardy review

70. In this chapter, you learned:  The network layer, or OSI Layer 3, provides services to allow end devices to exchange data across the network.  The network layer uses four basic processes: IP addressing for end devices, encapsulation, routing, and de-encapsulation.  The Internet is largely based on IPv4, which is still the most widely-used network layer protocol.  An IPv4 packet contains the IP header and the payload.  The IPv6 simplified header offers several advantages over IPv4, including better routing efficiency, simplified extension headers, and capability for per- flow processing.

71.  In addition to IP addressing, the network layer is also responsible for routing.  Hosts require a local routing table to ensure that packets are directed to the correct destination network.  The local default route is the route to the default gateway.  The default gateway is the IP address of a router interface connected to the local network.  When a router receives a packet, it examines the destination IP address to determine the destination network.

72.  The routing table of a router stores information about directly-connected routes and remote routes to IP networks.  If the router has an entry in its routing table for the destination network, the router forwards the packet.  If no routing entry exists, the router may forward the packet to its own default route, if one is configured, or it will drop the packet.  Routing table entries can be configured manually on each router to provide static routing or the routers may communicate route information dynamically between each other using a routing protocol.  In order for routers to be reachable, the router interface must be configured.

73. Chapter 6 Intro to Routing & Switching