1. Addressing end devices

2. Encapsulation

3. Routing

4. De-encapsulation

Internet Protocol Version 4 (IPv4) and

Internet Protocol Version 6 (IPv6)

1. Connectionless: No connection with the destination is established before sending data packets.
2. Best Effort: IP is inherently unreliable because packet delivery is not guaranteed.
3. Media Independent: Operation is independent of the medium (i.e., copper, fiber optic, or wireless) carrying the data.

Maximum Transmission Unit

This refers to the maximum size of the PDU that each medium can transport. This is established by the network layer after the data link layer passes this information to the network layer. 

The Maximum Transmission Unit (MTU), which is the maximum size that a packet can be to be transported on a specific medium, and this information is considered by the network layer when packets are created.

Name the following parts in the diagram. What is this a diagram of?

[image]

IPv4 Protocol Header

1. Version
2. Internet Header Length
3. Differentiated Services (DS)
4. Differentiated Services Code Point (DSCP)
5. Explicit Congestion Notification (ECN)
6. Total Length
7. Identification
8. Flag
9. Fragment Offset
10. Time-to-Live
11. Protocol
12. Header Checksum
13. Source IP Address
14. Destination IP Address

The Time-to-Live (TTL) contains an 8-bit binary value that is used to limit the lifetime of a packet. The packet sender sets the initial TTL value, and it is decreased by one each time the packet is processed by a router. If the TTL field decrements to zero, the router discards the packet and sends an Internet Control Message Protocol (ICMP) Time Exceeded message to the source IP address.

Source IPv4 Address: Always unicast

Destination IPv4 Address: Unicast, multicast, or broadcast

1. IP address depletion - Not enough unique, public IP addresses to go around.
2. Internet routing table expansion - A routing table is used by routers to make best path determinations. As the number of servers connected to the Internet increases, so too does the number of network routes. These IPv4 routes consume a great deal of memory and processor resources on Internet routers.
3. Lack of end-to-end connectivity - Network Address Translation (NAT) is a technology commonly implemented within IPv4 networks. NAT provides a way for multiple devices to share a single public IPv4 address. However, because the public IPv4 address is shared, the IPv4 address of an internal network host is hidden. This can be problematic for technologies that require end-to-end connectivity.

Network Address Translation

NAT provides a way for multiple devices to share a single public IPv4 address. However, because the public IPv4 address is shared, the IPv4 address of an internal network host is hidden. This can be problematic for technologies that require end-to-end connectivity.

How many unique IPv4 addresses are possible?

How many unique IPv6 addresses are possible?

IPv4: 4 billion

IPv6: 340 undecillion (1 undecillion: 10^36)

1. Increased address space - IPv6 addresses are based on 128-bit hierarchical addressing as opposed to IPv4 with 32 bits.
2. Improved packet handling - The IPv6 header has been simplified with fewer fields for more efficient packet handling.
3. Eliminates the need for NAT - With such a large number of public IPv6 addresses, NAT between a private IPv4 address and a public IPv4 is not needed. This avoids some of the NAT-induced application problems experienced by applications requiring end-to-end connectivity.
4. Larger Payload - Larger payload for increased throughput and transport efficiency.
5. Hierarchical network architecture for routing efficiency.
6. Autoconfiguration for addresses.

Name the fields in the following diagram. What is this a diagram of?

[image]

IPv6 Packet Header

1. Version
2. Traffic Class
3. Flow Label
4. Payload Length
5. Next Header
6. Hop Limit
7. Source IP Address
8. Destination IP Address

1. Itself

2. A local host.

3. A remote host.

dynamically from Dynamic Host Configuration Protocol (DHCP)

configured manually

Having a default gateway configured creates a default route in the routing table of the PC. A default route is the route or pathway your computer will take when it tries to contact a remote network. 

The default route is derived from the default gateway configuration and is placed in the host computer’s routing table. 

route print

netstat -r

1. Interface List - Lists the Media Access Control (MAC) address and assigned interface number of every network-capable interface on the host, including Ethernet, Wi-Fi, and Bluetooth adapters.
2. IPv4 Route Table - Lists all known IPv4 routes, including direct connections, local network, and local default routes.
3. IPv6 Route Table - Lists all known IPv6 routes, including direct connections, local network, and local default routes.

1. Directly-connected routes - These routes come from the active router interfaces. Routers add a directly connected route when an interface is configured with an IP address and is activated. Each of the router's interfaces is connected to a different network segment.
2. Remote routes - These routes come from remote networks connected to other routers. Routes to these networks can be manually configured on the local router by the network administrator or dynamically configured by enabling the local router to exchange routing information with other routers using a dynamic routing protocol.
3. Default route – Like a host, routers also use a default route as a last resort if there is no other route to the desired network in the routing table.

1. C - Identifies a directly-connected network. Directly-connected networks are automatically created when an interface is configured with an IP address and activated.
2. L - Identifies that this is a local interface. This is the IPv4 address of the interface on the router.

Describe the following three portions of a directly connected routing table entry.

[image]

1. Route Source: Identifies how the network was learned by the router.
2. Destination Network: Identifies the destination network and how it was learned.
3. Outgoing Interface: Identifies the exit interface to use to forward a packet toward the final destination.

Name and describe the following parts of a router's remote network routing table entry:

[image]

1. Route Source: Identifies how the network was learned by the router. Common route sources include S (static route), D (Enhanced Interior Gateway Routing Protocol or EIGRP), and O (Open Shortest Path First or OSPF).
2. Destination Network: Identifies the destination network.
3. Administrative Distance: Identifies the administrative distance (i.e., trustworthiness) of the route source. Lower values indicate increased trustworthiness of the route source.
4. Metric: Identifies the value assigned to reach the remote network. Lower values indicate preferred routes.
5. via
6. Next-Hop: Identifies the IP address of the next router to forward the packet to, in order to get to the destination network.
7. Route Timestamp: Identifies when the next-hop router was last heard from.
8. Outgoing Interface: Identifies the exit interface on the router to use to forward a packet toward the final destination.

A next-hop address is the address of a router to which another router that currently has a packet must forward the packet to, in order for the packet to eventually reach its destination.

When a packet destined for a remote network arrives at the router, the router matches the destination network to a route in the routing table. If a match is found, the router forwards the packet to the next hop address out of the identified interface.

1. Branch - Teleworkers, small businesses, and medium-size branch sites. Includes Cisco Integrated Services Routers (ISR) G2 (2nd generation).
2. WAN - Large businesses, organizations, and enterprises. Includes the Cisco Catalyst Series Switches and the Cisco Aggregation Services Routers (ASR).
3. Service Provider - Large service providers. Includes Cisco ASR, Cisco CRS-3 Carrier Routing System, and 7600 Series routers.

Learning about the branch routers is the focus of the CCNA certification.

1. Central processing units (CPU).
2. Operating systems (OS).
3. Memory consisting of random-access memory (RAM), read-only memory (ROM), nonvolatile random-access memory (NVRAM), and flash.

1. RAM - This is volatile memory used in Cisco routers to store applications, processes, and data needed to be executed by the CPU. Cisco routers use a fast type of RAM called synchronous dynamic random access memory (SDRAM).
2. ROM - This non-volatile memory is used to store crucial operational instructions and a limited IOS. Specifically, ROM is firmware embedded on an integrated circuit inside the router which can only be altered by Cisco.
3. NVRAM – This is non-volatile memory is used as the permanent storage for the startup configuration file (startup-config).
4. Flash - This non-volatile computer memory used as permanent storage for the IOS and other system related files such as log files, voice configuration files, HTML files, backup configurations, and more. When a router is rebooted, the IOS is copied from flash into RAM.

flash

RAM

1. The IOS image and running configuration file
2. The routing table used to determine the best path to use to forward packets
3. The ARP cache used to map IPv4 addresses to MAC addresses
4. The Packet buffer used to temporarily store packets before forwarding to the destination

1. Bootup information that provides the startup instructions
2. Power-on self-test (POST) that tests all the hardware components
3. Limited IOS to provide a backup version of the IOS. It is used for loading a full feature IOS when it has been deleted or corrupted.

Fill in the table below.

[image]

1. Running IOS
2. Routing Table, ARP Table
3. Running Configuration File
4. Packet Buffer
5. Startup Configuration File
6. IOS Files
7. POST, ROM Monitor Firmware (Limited IOS)

Enhanced High-Speed WAN Interface Card slot

Labeled as eHWIC 0 and eHWIC 1 to provide modularity and flexibility by enabling the router to support different types of interface modules, including serial, digital subscriber line (DSL), switch port, and wireless.

1. Console – This is a physical management port that provides out-of-band access to a Cisco device. Out-of-band access refers to access via a dedicated management channel that is used for device maintenance purposes only.
2. Secure Shell (SSH) – SSH is a method for remotely establishing a secure CLI connection through a virtual interface, over a network. Unlike a console connection, SSH connections require active networking services on the device including an active interface configured with an address.
3. Telnet - Telnet is an insecure method of remotely establishing a CLI session through a virtual interface, over a network. Unlike SSH, Telnet does not provide a securely encrypted connection. User authentication, passwords, and commands are sent over the network in plaintext.

In-Band Router Interfaces: Are the LAN (i.e. Gigabit Ethernet) and WAN (i.e., eHWICs) interfaces configured with IP addressing to carry user traffic. Ethernet interfaces are the most common LAN connections, while common WAN connections include serial and DSL interfaces.

Management Ports: Include the console and AUX ports which are used to configure, manage, and troubleshoot the router. Unlike LAN and WAN interfaces, management ports are not used for packet forwarding user traffic.

Ethernet LAN Interfaces: Labeled GE 0/0 (i.e., G0/0) and GE 0/1 (i.e., G0/1). Ethernet interfaces are used for connecting to other Ethernet-enabled devices including switches, routers, firewalls, etc. Each LAN interface has its own IPv4 address and subnet mask and/or IPv6 address and prefix, which identifies it as a member of a specific network.

Serial WAN Interfaces: Added to eHWIC0 and labeled Serial 0 (i.e., S0/0/0) and Serial 1 (i.e., S0/0/1). Serial interfaces are used for connecting routers to external WAN networks. Each serial WAN interface has its own IP address and subnet mask, which identifies it as a member of a specific network.

Files Copied to RAM during Bootup

Fill in the following table:

[image]

1. IOS image

2. Other system-related files

3. Cisco IOS

4. startup-config

5. running-config

1. Perform the POST and load the bootstrap program.

2. Locate and load the Cisco IOS software.

3. Locate and load the startup configuration file or enter setup mode.

1. Performing POST and Load Bootstrap Program

During the Power-On Self-Test (POST), the router executes diagnostics from ROM on several hardware components, including the CPU, RAM, and NVRAM. After the POST, the bootstrap program is copied from ROM into RAM. The main task of the bootstrap program is to locate the Cisco IOS and load it into RAM.

Note: At this point, if you have a console connection to the router, you begin to see the output on the screen.

2. Locating and Loading Cisco IOS

The IOS is typically stored in flash memory and is copied into RAM for execution by the CPU. If the IOS image is not located in flash, then the router may look for it using a Trivial File Transfer Protocol (TFTP) server. If a full IOS image cannot be located, a limited IOS is copied into RAM, which can be used to diagnose problems and transfer a full IOS into Flash memory.

3. Locating and Loading the Configuration File

The bootstrap program then copies the startup configuration file from NVRAM into RAM. This becomes the running configuration. If the startup configuration file does not exist in NVRAM, the router may be configured to search for a TFTP server. If a TFTP server is not found, then the router displays the setup mode prompt.

No.

If you do enter setup mode, press Ctrl+C to exit setup mode. 

1. Configure the device name

hostname name

2. Secure user EXEC mode

line console 0

password password

login

3. Secure remote Telnet / SSH access

line vty 0 15

password password

login

4. Secure privileged EXEC mode

enable secret password

5. Secure all passwords in the config file

service password-encryption

6. Provide legal notification

banner motd delimiter message delimiter

7. Save the configuration

copy running-config  startup-config

1. interface type-and-number
2. description  description-text
3. ip address ipv4-address subnet-mask
4. no shutdown

Information about the type of network that the interface is connected to, and whether there are any routers on that network.

 If the interface connects to an ISP or service carrier, enter the third party connection and contact information.

Status of “up”

Protocol of “up”

1. show ip route - Displays the contents of the IPv4 routing table stored in RAM.
2. show interfaces - Displays statistics for all interfaces on the device.
3. show ip interface - Displays the IPv4 statistics for all interfaces on a router.

IPv4 address

subnet mask

default gateway address