**packet switching
extension of network segments
**segmentation of broadcast domains
**selection of best path based on logical addressing
selection of best path based on physical addressing
Describe the internal and external router hardware components and the purpose of each.
Central Processing Unit (CPU)—Executes operating system instructions, such as system
initialization, routing functions, and network interface control.
Random-Access Memory (RAW)—Stores the routing table and other data structures that the router
needs when forwarding packets.
Read-Only Memory (ROM) —Holds basic diagnostic software used when the router is powered on.
Non-Volalile RAM (NVRAM)—Stores the startup configuration, including IP addresses, routing
protocol and other related information NVRAM is a portion of the Boot ROM chip
Flash memory —Stores the operating system (Cisco IDS) and other files.
LAN interfaces such as Ethernet and FastEthernet are used for connecting to different LANs
WAN interlaces are used for connecting to a variety of serial links including T1. DSL and ISDN.
Describe the router bootup process from power on to final configuration.
Test router hardware:
1. Perform POST.
2. Execute Bootstrap Loader.
Locale and load the Cisco IDS software:
3. Locate the IOS.
4. Load the [OS.
Locate and load the startup configuration file or enter Setup mode:
5. Locate the Configuration File.
6. Execute the Configuration File.
7. Enter Setup Mode.
Note: If a full IOS image can not be located, a scaled-down version of the IOS is copied from ROM into RAM. This version of IOS is used to help diagnose any problems and can be used to load a complete version of the IOS into RAM. If the startup configuration file does not exist in NVRAM, the router may search for a TFTP server. If the router detects that it has an active link to another configured router it sends a broadcast searching for a configuration file across the active link
What important features does a router add to the network?
Determining the best path to send packets
Forwarding packets toward their destination
Describe the steps necessary to apply a basic configuration to a router.
Name the router
Set passwords
Configure interfaces
Configure a banner
Save changes on a router
Verify basic configuration and router operations
Describe the importance of the routing table. What purposes does it serve?
A routing table provides the router with the necessary information to carry out its primary function—forwarding packets toward the destination network.
What are the three basic ways a router learns about networks?
Connected Routes
Static Routes
Dynamic Routes
For your current studies what are the most important fields in the IP header and why are they important?
Version—version of IP currently used is IPv4
Time to Live (TTL)—number of routers a packet can traverse before being dropped
Source IP address—32-bt source IP address
Destination IP address—32-bit destination IP address
Describe the encapsulation/decapsulation process as a packet travels from source to destination
The source encapsulates data in a packet with soure and destination IP addresses. It then encapsulates the packet into a frame with source and destination MAC addresses and sends the frame out as bits on the wire The frame is received by the source's gateway—a router—a is decapsulated. If the destination MAC address is the router then the router will search the routing table for an outgoing interface to the destination, encapsulate the packet in the appropriate frame format for the outgoing interface with new source and destination layer 2 addresses and forward the frame out the interface. This process is repeated at each router along the path until the packet reaches the destination From source to destination the layer 2 addresses change at each hop. However, the source and destination addresses do not change.
When you think about the difference between the hardware and software of a PC and a router, what do you see as the strengths and weaknesses of each device? Which device do you think is the more powerful and why?
Your answer should revolve around the understanding that a router is a single-purpose device and a computer is a multi-purpose device
As you study, learn, and use the command line interface on a Cisco router, do you see a time when you may not need to use the CLI to configure routers and switches? What does your vision of network configuration tasks look like without the CLI?
Answers will vary. However. CLI is still the dominate way to complete configuration tasks. Like DOS commands. CLI commands will most likely continue to be favored among network administrators as the primary way to complete many configuration or verification tasks even when a more intuitive and easier to use GUI becomes available.
If you could design your own routing protocol algorithm to route packets, what would its mam features be? How would your protocol decide on the best route? Remember, a computer is going to implement your idea: therefore, be specific
Answers will vary Your description should include a step-by-step process. To see pseudocode for current routing algorithms, seach the web for Bellman-Ford and Dykstra algorithms.
Although the Internet Protocol is now consider the only protocol to use for Layer 3 addressing, this was not always the case. Investigate and report on some other Layer 3 protocols that serve the same purpose. What features do they share in common with IP7 How are they different?
A hierachical structure is common to all layer 3 addressing protocols. Each one identifies a network portion and a host portion. How each does this is different. For example Novell's Internet Packet Exchange uses an 30-bit address. The first 32 bits are designated network bits and are determined by the administrator. The remaining 48 bits are the same as the MAC address of the host.
