Course Content
Networking Today
0/7
Network Components
Network Representations and Topologies
Common Types of Networks
Internet Connections
Reliable Networks
Network Security Basic
Network Trends
Basic Switch and End Device Configuration
0/7
Cisco IOS Access
Cisco IOS Navigation
Cisco IOS Command Structure
Basic Cisco Device Configuration
Save Cisco IOS Configurations
Ports and Addresses
Configure IP Addressing
Protocols and Models
0/7
The Rules in Network Communications
Protocols
Protocol Suites
Standards Organizations
Reference Models
Data Encapsulation
Data Access
Physical Layer
0/6
Purpose of the Physical Layer
Physical Layer Characteristics
Copper Cabling
UTP Cabling
Fiber-Optic Cabling
Wireless Media
Data Link Layer
0/3
Purpose of the Data Link Layer
WAN and LAN topologies
Data Link Frame
Ethernet Switching
0/4
Ethernet Frames
Ethernet MAC Address
The MAC Address Table
Switch Speeds and Forwarding Methods
Network Layer
0/5
Network Layer Characteristics
IPv4 Packet
IPv6 Packet
How a Host Routes
Router Routing Tables
Number Systems
0/2
Binary Number System
Hexadecimal Number System
Address Resolution
Explain how ARP and ND enable communication on a network
0/3
MAC and IP
ARP
Neighbor Discovery
Basic Router Configuration
0/3
Configure Initial Router Settings
Configure Interfaces
Configure the Default Gateway
IPv4 Addressing
0/7
IPv4 Address Structure
IPv4 Unicast, Broadcast, and Multicast
Types of IPv4 Addresses
Network Segmentation
Subnet an IPv4 Network
VLSM
Structured Design
IPv6 Addressing
0/8
IPv4 Issues
IPv6 Address Representation
IPv6 Address Types
GUA and LLA Static Configuration
Dynamic Addressing for IPv6 GUAs
Dynamic Addressing for IPv6 LLAs
IPv6 Multicast Addresses
Subnet an IPv6 Network
ICMP
0/2
ICMP Messages
Ping and Traceroute Testing
Transport Layer
0/7
Transportation of Data
TCP Overview
UDP Overview
Port Numbers
TCP Communication Process
Reliability and Flow Control
UDP Communication
Application Layer
0/7
Application, Presentation, and Session
Peer-to-Peer
Web Protocols
Email Protocols
Dynamic Host Configuration Protocol (DHCP)
Domain Name Service
File Sharing Services
Network Security Fundamentals
0/4
Security Threats and Vulnerabilities
Network Attacks
Network Attack Mitigation
Device Security
Build a Small Network
0/7
Devices in a Small Network
Small Network Applications and Protocols
Scale to Larger Networks
Verify Connectivity
Host and IOS Commands
Troubleshooting Methodologies
Troubleshooting Scenarios
Basic Device Configuration
0/5
Configure a Switch with Initial Settings
Configure Switch Ports
Secure Remote Access
Basic Router Configuration
Verify Directly Connected Networks
CCNA: Switching, Routing, and Wireless Essentials
The second course in the CCNA curriculum focuses on switching technologies and router operations that support small-to-medium business networks and includes wireless local area networks (WLAN) and security concepts.
0/15
Switching Concepts
VLANs
Inter-VLAN Routing
STP
Etherchannel
DHCPv4
SLAAC and DHCPv6 Concepts
FHRP Concepts
LAN Security Concepts
Switch Security Configuration
WLAN Concepts
WLAN Configuration
Routing Concepts
IP Static Routing
Troubleshoot Static and Default Routes
CCNA: Enterprise Networking, Security, and Automation
The third CCNA course describes the architectures and considerations related to designing, securing, operating, and troubleshooting enterprise networks – including wide area network (WAN) technologies & quality of service (QoS) mechanisms for secure remote access, along with software-defined networking, virtualization, & automation concepts supporting network digitization.
0/14
Single-Area OSPFv2 Concepts
Single-Area OSPFv2 Configuration
Network Security Concepts
ACLs Concepts
ACLS for IPv4 Configuration
NAT for IPv4
WAN Concepts
VPN and IPsec Concepts
QoS Concepts
Network Management
Network Design
Network Troubleshooting
Network Virtualization
Network Automation
CCNA Course
About Lesson

Data Access

Explain how local hosts access local resources on a network.

 

Addresses

  • Both the data link and network layers use addressing to deliver data from source to destination.
  • Network layer source and destination addresses – Responsible for delivering the IP packet from original source to the final destination.
  • Data link layer source and destination addresses – Responsible for delivering the data link frame from one network interface card (NIC) to another NIC on the same network.

Protocols and Models

Layer 3 Logical Address

The IP packet contains two IP addresses:

  • Source IP address – The IP address of the sending device, original source of the packet.
  • Destination IP address – The IP address of the receiving device, final destination of the packet.

These addresses may be on the same link or remote. An IP address contains two parts: Network portion (IPv4) or Prefix (IPv6) 

  • The left-most part of the address indicates the network group which the IP address is a member.
  • Each LAN or WAN will have the same network portion.

Host portion (IPv4) or Interface ID (IPv6) 

  • The remaining part of the address identifies a specific device within the group.
  • This portion is unique for each device on the network.

Devices on the Same Network

When devices are on the same network the source and destination will have the same number in network portion of the address.

  • PC1 – 192.168.1.110
  • FTP Server – 192.168.1.9

Protocols and Models

Role of the Data Link Layer Addresses: Same IP Network

When devices are on the same Ethernet network the data link frame will use the actual MAC address of the destination NIC. MAC addresses are physically embedded into the Ethernet NIC and are local addressing.

  • The Source MAC address will be that of the originator on the link.
  • The Destination MAC address will always be on the same link as the source, even if the ultimate destination is remote.

Devices on a Remote Network

  • What happens when the actual (ultimate) destination is not on the same LAN and is remote?
  • What happens when PC1 tries to reach the Web Server?
  • Does this impact the network and data link layers?

Role of the Network Layer Addresses

When the source and destination have a different network portion, this means they are on different networks.

  • PC1 – 192.168.1
  • Web Server – 172.16.1

Protocols and Models When the final destination is remote, Layer 3 will provide Layer 2 with the local default gateway IP address, also known as the router address.   Protocols and Models

  • The default gateway (DGW) is the router interface IP address that is part of this LAN and will be the “door” or “gateway” to all other remote locations.
  • All devices on the LAN must be told about this address or their traffic will be confined to the LAN only.
  • Once Layer 2 on PC1 forwards to the default gateway (Router), the router then can start the routing process of getting the information to actual destination.
  • The data link addressing is local addressing so it will have a source and destination for each link.
  • The MAC addressing for the first segment is : Source – AA-AA-AA-AA-AA-AA (PC1) Sends the frame. Destination – 11-11-11-11-11-11 (R1- Default Gateway MAC) Receives the frame.

Note: While the L2 local addressing will change from link to link or hop to hop, the L3 addressing remains the same.

Data Link Addresses

Since data link addressing is local addressing, it will have a source and destination for each segment or hop of the journey to the destination. The MAC addressing for the first segment is:

  • Source – (PC1 NIC) sends frame
  • Destination – (First Router- DGW interface) receives frame

The MAC addressing for the second hop is:

  • Source – (First Router- exit interface) sends frame
  • Destination – (Second Router) receives frame

Protocols and Models   The MAC addressing for the last segment is:

  • Source – (Second Router- exit interface) sends frame
  • Destination – (Web Server NIC) receives frame

Protocols and Models   Notice that the packet is not modified, but the frame is changed, therefore the L3 IP addressing does not change from segment to segment like the L2 MAC addressing. The L3 addressing remains the same since it is global and the ultimate destination is still the Web Server.  

 

Other related topics

 

Topic Title Topic Objective
The Rules in Network Communications Describe the types of rules that are necessary to successfully communicate.
Protocols Explain why protocols are necessary in network communication.
Protocol Suites Explain the purpose of adhering to a protocol suite.
Standards Organizations Explain the role of standards organizations in establishing protocols for network interoperability.
Reference Models Explain how the TCP/IP model and the OSI model are used to facilitate standardization in the communication process.
Data Encapsulation Explain how data encapsulation allows data to be transported across the network.
Data Access Explain how local hosts access local resources on a network.

 

 Other useful information

 

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