Chapter 3 CCNA Discovery Encapsulation - Explanations and Clarifications CCNA Discovery Encapsulation - Explanations and Clarifications

Why Network? Share resources Files Internet Connections Printers Scanners IM Share resources Files Internet Connections Printers Scanners IM

Define the Pieces Hosts PC’s Send and Receive Information Directly connected to a Network Device Hosts PC’s Send and Receive Information Directly connected to a Network Device

Define the Pieces Peripherals Not directly connected to the Network, but are connected through a PC. Peripherals Not directly connected to the Network, but are connected through a PC.

Define the Pieces Network Devices Hub - Dumb device Whatever goes in one port comes out all ports Switch - Smart Device Connects only to the target device by using a lookup table Uses MAC addresses Network Devices Hub - Dumb device Whatever goes in one port comes out all ports Switch - Smart Device Connects only to the target device by using a lookup table Uses MAC addresses

Hub vs. Switch 1 Collision Domain for the Entire Device One Way Communication No Routing Table 1 Collision Domain for the Entire Device One Way Communication No Routing Table Each Port is a Collision Domain (Private Line) Two-way (Full Duplex) Communications Routing Table

Define the Pieces Router The major traffic cop Forwards by using IP Addresses Blocks Broadcasts This is what makes the Internet work Very Smart Routing Re-Routes traffic based upon changing conditions. Router The major traffic cop Forwards by using IP Addresses Blocks Broadcasts This is what makes the Internet work Very Smart Routing Re-Routes traffic based upon changing conditions.

Define the Pieces Network Media Carries the Data Connects Hosts and Devices Copper Wire Fiber Wireless Network Media Carries the Data Connects Hosts and Devices Copper Wire Fiber Wireless

2 Types of Networks Peer to Peer No centralized administration or control Administered Network Centralized Server System Administrator controls access to services/resources Peer to Peer No centralized administration or control Administered Network Centralized Server System Administrator controls access to services/resources

2 Ways to Map a Network Physical Shows where devices are physically located Shows how devices are connected Physical Shows where devices are physically located Shows how devices are connected

2 Ways to Map a Network Logical Shows how the host uses the network Shows Host Names, IP Addresses, Groups and Applications Logical Shows how the host uses the network Shows Host Names, IP Addresses, Groups and Applications

How Files are Moved Each Chunk called a “Packet” is individually acknowledged. If it is damaged or missing the receiving computer requests that it be resent. At the simplest level the header includes the number of bits in the packet. If the count is off an error is assumed. Each Chunk called a “Packet” is individually acknowledged. If it is damaged or missing the receiving computer requests that it be resent. At the simplest level the header includes the number of bits in the packet. If the count is off an error is assumed.

How Files Are Moved Files are first broken down into packets That way is a piece needs to be resent due to an error, it wil be smaller and faster. Then they are encapsulated. Headers and footers are added to indicate sender and receiver. Packets are numbered so they can be identified for reassembly. They may not arrive in order. Files are first broken down into packets That way is a piece needs to be resent due to an error, it wil be smaller and faster. Then they are encapsulated. Headers and footers are added to indicate sender and receiver. Packets are numbered so they can be identified for reassembly. They may not arrive in order.

Rules Rules are applied to control how data is organized. The term for these rules is a “protocol”. Every manufacturer must follow these rules so that all devices can communicate. Rules are applied to control how data is organized. The term for these rules is a “protocol”. Every manufacturer must follow these rules so that all devices can communicate.

Rules Parts of a Packet Destination MAC Address Source MAC address (Last Hop) Start Flag Recipient Identifier Sender Identifier Data End of Packet indicator Parts of a Packet Destination MAC Address Source MAC address (Last Hop) Start Flag Recipient Identifier Sender Identifier Data End of Packet indicator

Encapsulation Turning a chunk of data into a packet to be sent is called encapsulation. This encoding process is then followed by de-encoding on the other end. Think of putting a letter into an envelope, then removing it from the envelope in order to read it. Turning a chunk of data into a packet to be sent is called encapsulation. This encoding process is then followed by de-encoding on the other end. Think of putting a letter into an envelope, then removing it from the envelope in order to read it.