CISCO (2).docx

**CHAPTER 1: NETWORKING TODAY** **CISCO** is founded in **1997** **1.2 NETWORK COMPONENTS** - **HOST ROLES** - **Host --** all computers that are connected to a network and participate directly in network communication. Host can also be called as **end devices,** and some hosts are '...

**CHAPTER 1: NETWORKING TODAY** **CISCO** is founded in **1997** **1.2 NETWORK COMPONENTS** - **HOST ROLES** - **Host --** all computers that are connected to a network and participate directly in network communication. Host can also be called as **end devices,** and some hosts are '**clients**'. - **Internet Protocol Address (IP Address)** -- a number that identifies the host within a network. It also identifies the host and the network to which the host is attached. - **Servers** -- are **COMPUTERS WITH SOFTWARE** that **ALLOW THEM TO PROVIDE INFORMATION.** - **Clients** -- have software for requesting and displaying information obtained from the server. - **Peer-to-Peer** - Is used in small businesses at homes. Computers function as **SERVERS AND CLIENTS** on the network. - **End Devices** - To distinguish one device from another, end devices are given unique addresses. When a device initiates communication, it uses the address of the devices to deliver the message. An end device is either the source or destination of a message transmitted over the network. - **Intermediary Devices** - connects the individual end devices to the network. they can connect multiple networks together to create an internetwork. provides connectivity and ensure that data flows across the network. these devices use the device addresses and the information about the internetwork to determine the path the message will take. - Wireless Router - LAN Switch - Router - Multilayer Switch - Firewall Appliance - **Network Media** - Where communications transmit across provides a channel for data to travel from source to destination. **1.3 NETWORK REPRESENTATIONS AND TOPOLOGIES** **TOPOLOGY DIAGRAM** - are used to represent networks: the components, what the network looks like, where are specific components located. provides a way to easily understand how devices connect to a large network. There are two types of diagrams: physical and logical. - **Physical topology diagrams** illustrate the physical location of intermediary devices and cable installation - **Logical topology diagrams** illustrate the devices, ports, and the addressing scheme of the network. shows which devices are connected to intermediary devices and what network media is used. - **ADDITIONAL TERMINOOGIES** - **NIC (Network Interface Card)** -- physically connects the end device to the network. - **Physical Port** -- where the network media connects, a connector/outlet. - **Interface** -- specialized ports that connect to individual networks, routers connect networks, its ports are called network interfaces. **1.4 Common Types of Networks**  **LAN (LOCAL AREA NETWORK)** - Provides to users and devices within a small geographic area, it is used in departments within enterprises, homes, or a small business network, it also provides high-speed bandwidth within the network and usually administered by an individual or an organization. **WAN (WIDE AREA NETWORK)** - It connects networks on wide geographic area and typically owned by a large corporation to telecommunication service providers, this also interconnect LANs within a wide geographic area. **THE INTERNET** - Also known as **internetwork**, it is a collection of interconnected networks and not owned by any individual or group. - **INTRANET** - private connections of LANs ans WANs that belongs to a private organization and also designed to only be accessible to the organization's members, employees, etc. - **EXTRANET** - For people outside the organization, to give them secure and safe access. **1.5 INTERNET CONNECTIONS** **HOME AND SMALL OFFICE INTERNET CONNECTIONS** - **CABLE** -- typically offered by cable television service providers, the internet data signal is transmitted in the same cable that provides the cable television. - **DSL** -- Digital subscriber line, this also runs over a telephone line and also a home and small offices that connect to the internet using ADSL. - **CELLULAR** -- uses a cellphone to connect to the internet and is connected to the cellular tower. - **SATELLITE** -- availability is the benefit and require a clear line of sight to the satellite. - **DIAL-UP TELEPHONE** -- it is an inexpensive option and uses and phone and a modem, this type is a low bandwidth and useful for mobile access while traveling. **BUSINESSES INTERNET CONNECTIONS (Required higher bandwidths)** - **DEDICATED LEASE LINES** -- reserved circuits within the service provider's network and connect geographically separated offices for private voice or data networking, rented in a monthly or yearly rate. - **METRO ETHERNET** -- Ethernet WAN, this extends LAN Technology into WAN. - **BUSSINESS** -- this type of connection has various formats, popular choice is SDSL -- same download and upload speeds. - **SATELLITE** -- can provide solutions when wired connections is not available. **1.6 RELIABLE NETWORKS** **Network Architecture** -- this term refers to, in some context, to the technologies that support the infrastructures and the programmed services and rules, or protocols, that moves the data across the network. **FOUR BASIC CHARACTERISTICS IN NETWORK TOLERANCE** - **Fault Tolerance** - It is a network that minimizes data loss during transit and limits the affected devices when devices fail. - Allows quick recovery of data/routes, has redundancy, and splits traffic into packets that are routed over shared network. - **Scalability** - It is a network that is able to quickly expand to support new users and applications. - **Quality of Service (QoS)** - An increasing requirement of today - when the demand for the bandwidth exceeds the amount available - when congestion happens, the devices will hold the packets until it is able to be transmitted to its destination - webpages are usually low in priority, while voice over IP is high priority - **Network Security** -- network infrastructure and information security. **1.7 NETWORK TRENDS** **1. Bring your own device (BYOD)** - enables users to bring their own personal device to access information and communicate across a business or campus network - means by any device, with any ownership, used anywhere **2. Online Collaboration** \- networks enabled collaboration with no regard to the physical distance. **3. Video Communications** \- video is used for communications, and is a powerful tool for communication. **4. Clouds Computing** \- one way we can store data and allows us to create backups in servers over the internet. This is possible because of data centers. **Data Centers --** are facilities that are used to house computer systems and related components and can also occupy a room of a building, one or more floors, or even a whole warehouse. **TYPES OF CLOUD COMPUTING** - **PUBLIC CLOUDS** - **PRIVATE CLOUDS** - **HYBRID CLOUDS** - **COMMUNITY CLOUDS** **WIRELESS INTERNET SERVICE PROVIDER (WISP)** - an ISP that connects subscribers to a designated access point using wireless technology (usually a hotspot can be found in home wireless local area networks (WLAN) commonly found in rural areas where DSL or cable services are not available. **1.8 Network Security** **SECURITY THREATS** - **Viruses, worms, trojan horses** - contains malicious code or software running on a user device. - **Spyware and Adware** - Secretly collects data about the user. - **Zero-day attacks** - Attacks that happen om the first day of vulnerability is known. - **Threat actor attacks** - Malicious person attacks user devices or network device. - **Denial of service** - slow or crash applications and processes in a network device. - **Data interception and theft** - Captures private information from an organization's device. - **Identity theft** - States login credentials to steal data. **SECURITY SOLUTIONS** - **Antivirus and Antispyware** - Protect end devices from getting infected with malicious software. - **Firewall Filtering** - Bocks unauthorized access into and out a network. This includes host-based firewalls.  **CHAPTER 3 : Protocols and Models** **3.1 The RULES** **3 Communication Fundamentals** \- The source (sender) \- The destination (receiver) \- The channel (media) **Communication Protocols** **-** Protocols are the rules that communications will follow. Rules will very depending on the protocols. **Network Protocol Requirements** **-** Message encoding \- Message formatting and encapsulation \- Message size \- Message timing \- Message delivery options \* **MESSAGE ENCODING** **- Encoding** is the process of converting information into another acceptable form for transmission. **Decoding** reverses this process to interpret this information. \* **MESSAGE FORMATTING AND ENCAPSULATION** **-** When a message is sent, it must use a specific format or structure. Message format depends on the type of message and the channel that is used to deliver the message. \* **MESSAGE SIZE** \- Message sent across the network are converted to **bits**. The bits are encoded into pattern of light, sound, or electrical impulses. \- The destination host must decode the signals to interpret the message. \* **MESSAGE TIMING** \* message timing includes the following \- flow control \* process of managing the rate of data transmission \- response timeout \* how long to wait for responses and specify appropriate actions to take if response timeouts occur \- access method \* collision of information, what to do in such situations \* to determine whether a line is available \- full-duplex \* 2 way \- half-duplex \* 1 way **\* MESSAGE DELIVERY OPTIONS** \- messages can be delivered in different ways \* **unicast** - deliver one-to-one \* **multicast** - deliver to multiple people but not all \* **broadcast** - deliver to all \* **PROTOCOLS** **\* Network Protocols** \- a common format and set of rules for exchanging data between devices, implemented by end devices and intermediary devices in software, hardware, or both, each protocol has its own function, format and rules for communication. **TYPES OF PROTOCOLS** - **Network Communications Protocols -** enable two or more devices to communicate over one or more networks. **Family of Technologies** - **IP (Internet Protocol)** - **TCP (Transmission control protocol)** - **HTTP (Hyper-text transfer protocol** - **Network Security Protocol** **-** protocols secure data to provide authentication, data integrity, and data encryption. - **SSH (Secure shell)** - **SSL (Secure sockets layer)** - **TLS (Transport layer security)** - **Routing Protocols -** enable routers to exchange route information, compare path information, and select the best path to the destination network. - **OSPF (open shortest path first)** - **BGP (border gateway protocol)** - **Service Discovery Protocols --** used for automatic detection of devices or services. - **DHCP (Dynamic host configuration protocol):** Discovers services for IP address allocation. - **DNS (Domain name system):** used to perform name-to-IP address translation. **NETWORK PROTOCOL FUNCTIONS** - **Addressing --** identifies the sender and intended receiver using a defined scheme. - **Reliability --** provides guaranteed delivery mechanisms in case messages are lost or corrupted in transit. (TCP) - **Flow Control --** ensures data flows at an efficient rate. - **Sequencing --** uniquely labels each transmitted segment of data. - **Error Detection --** used to determine if data became corrupted during transmission. - **Application Interface --** contains information used for process-to- -process communication between network applications. **PROTOCOL SUITES** - Are designed to work with each other seamlessly - Groups of inter-related protocols necessary to perform a communication function. **EVOLUTION OF PROTOCOL SUITES** - **TCP/IP --** most common and relevant protocol today - **OSI (Open Systems Interconnection) protocol --** family of protocols developed jointly in 1977. - **7 Layer Reference Model** -- mainly known today for its layered model, and have been largely replaced by the internet protocol suite. - **Apple Talk** -- short-lived proprietary protocol suite released by Apple Inc (1985). - **Novell Netware** -- short-lived proprietary protocol suite and network operating system developed by Novell Inc (1983).   **brief descriptions of some protocols** - **Application layer** **Name system** **DNS (domain name system)** - translates domain names to IP addresses **host config** **DHCPv4** - dynamic host configuration protocol for IPv6 - dynamically assigns IPv4 addressing information to DHCPv4 clients at start-up and allows the addresses to be re-used when no longer needed **DHCPv6** - DHCP for IPv6 - dynamically assigned IPv6 addressing information to DHCPv6 clients at start up **SLAAC (stateless address autoconfiguration)** - a method that allows a device to obtain its IPv6 addressing information without using a DHCPv6 server **Email** **SMTP** - simple mail transfer protocol - enables servers to send email to other servers **POP3 (post office protocol version 3)** - enables clients to retrieve email from a mail server and download the email to the client's local mail application **IMAP (Internet message access protocol)** - enables clients to access email stored on a mail server as well as maintaining email on the server **File transfer** **FTP (file transfer protocol)** - enable a user to access and transfer files to and from another host over a network - a reliable connection-oriented and acknowledged files delivery protocol **SFTP** - SSH file transfer protocol - extension to secure shell protocol - used to establish a a secure file transfer session in which the file transfer is encrypted **TFTP (trivial file transfer protocol)** - a simple, connectionless file transfer protocol with best-effort unacknowledged file delivery - uses less overhead than FTP **web and web service** **HTTP (hypertext transfer protocol)** - set of rules for exchanging text, graphic images, sournd video, and other multimedia files on the WWW **HTTPS** - HTTP secure - secure form of http that encrypts data that is exchanged over the WWW **REST (representation state transfer)** - web service that uses application programming interfaces and http requests to create web applications **transport layer** **connection-oriented** **TCP (transmission control protocol)** - enables reliable communication between processes running on separate hosts and provides readable, acknowledged transmissions that confirm successful delivery **connectionless** **UDP (user datagram protocol)** - enables a process running on one host to send packages to a process running on another host - does not confirm successful user datagranm transmission **internet layer** **internet protocol** **IPv4 (internet protocol version 4)** - receives message segments from the transport layer, packages messages into packets, and addresses packets for end-to-end delivery over a network - uses a 32-bit address **IPv6 (IP version 6)** - uses to IPv4 but uses a 128-bit address **NAT (Network address translation)** - translates IPv4 addresses from a private network into globally unique public IPv4 addresses **messaging** **ICMPv4 (internet control message protocol)** - provides feedback from a destination host to a source about erres in packet delivery **ICMPv6** - ICMP for IPv6 **ICMPv6 ND** - ICMPv6 Neighbor discovery - includes four protocol messages that are used for address resolution and duplicate address detection **routing protocols** **OSPF (open shortest path first)** - link-state routing protocol that uses a hierarchical design based on areas open standard interior routing protocol **EIGRP (enhanced interior gateway routing protocol)** - open standard routing protocol developed by Cisco that uses a composite metric based on bandwidth, delay, load, and reliability **BGP (border gateway protocol)** - open standard ecterior gateway routing protocol used between internet service providers - commonly used between ISPs and their large private clients to exchange routing information **network access layer** **address resolution** **ARP (address resolution protocol)** - provides dynamic address mapping between an IPv4 address and a hardware address **data link protocols** **ethernet** - defines the rules for wiring and signaling standards of the network access layer **WLAN (wireless local area network)** - defines rules for wireless signaling across the 2.4Ghz and 5Ghz radio frequencies **Standard Organizations** - **Open standards** - encourage interoperability, competition, and innovation among manufacturers of network components, guarantee that no single company can monopolize the market or have an unfair advantage over its competition. - **Internet standards** **ISOC -** responsible for promoting the open development and evolution of internet use **IAB-** responsible for the overall management and development of internet standards **IETF -** develops, updates, and maintains internet and TCP/IP technologies RFC (request for comments) documents process and documents for developing new protocols and updating existing protocols **IRTF** - focused on long-term research related to internet and TCP/IP protocols ex. anti-spam research group (ASRG), crypto forum research group (CFRG), and peer-to-peer research group (P2PRG) - **Electronic and communications standards** **Institute of electrical and electronics engineers (IEEE) -** organization of electrical and electronics and engineers dedicated to advancing technological innovation and creating standards in a wide area of industries includes 802.3 ethernet, 802.11 wlan standard **Electronic industries alliance (IEA) -** best known for its standard relating to electrical wiring, connectors, and the 19-inch racks used to mount networking devices **telecommunications industry association (TIA) -** responsible for developing communication standards in variety of areas **international telecommunications union-telecommunication standardization sector (ITU-T) -** one of the largest and oldest standards organizations**,** defines standards for video compression, internet protocol television (IPTV), and broadband communications (DSL). **LAYERED MODELS** **The OSI reference model -** provides and extensive list of functions and services that can occur at each layer, provides consistency with all types of network protocols and se4vices by describing what must be done at a particular layer **OSI Model Layer (Ang Pulis Sa Tulay Nahuog Dahil Pilay)** **7 -- application** - contains protocols used for process-to-process communications. **6 -- presentation** - provides common representation of the data transferred between application layer services. **5 -- session** - provides services to the presentation layer to organize its dialogue and to manage dta exchange. **4 -- transport** - defines services to segment, transfer, and reassemble, the data over the network identified end devices **3 - network** - provides services to exchange the individual pieces of data over the network between identified end devices **2 - data link** - describe methods for exchanging data frames between devices over a common media **1 -- physical** - describe the mechanical, electrical, functional, and procedural means to activate, maintain, and deacticate physical connections for a bit **transmission to and from a network device** **TCP / IP MODEL -- aka the internet model** **4 -- application** - represents data to the user, plus encoding, and dialog control. **3 -- transport -** supports communication between various devices across diverse networks. **2 - internet** determines the best path through the network. **1 -- network** - access controls the hardware devices and media that make up the network.  **Protocol data units (PDU)** - PDU is the form a piece of data takes at any layer of the network, UDP PDUs are called 'datagrams' or 'IP datagrams' **Types of PDU** - **Data -** at the application layer - **Segment -** at the transport layer - **Packet -** at the network layer - **Frame -** at the data link layer - **Bits -** at the physical layer **Network and data link layer source and destination addresses** **Network layer src. and dest. Addresses** - responsible for delivering the IP packet form original source to the final destination (remote or local) **Data link layer src. and dest. Addresses** - responsible for delivering the data link frame from one NIC to another NIC on the same network.  **IP address** - logical address used to deliver the IP packet from original source to the final destination **IP packet contains the following** - source IP address - destination IP address **IP addresses contain two parts** - **Network portion (IPv4) or Prefix (IPv6)** - left-most part of the address - all devices on the same network will have the same network portion of the address - **Host portion (IPv4) or Interface ID (IP6)** - the remaining part of the address that identifies the specific device on the network - unique for each device or interface on the network \*\*\* the subnet mask (IPv4) or prefix-length(IPv6) is used to identify the network portion of an IP address from the host portion **Role of the Data link (Layer 2) layer addresses: Same IP Network** - when the sender and receiver of the IP packet are ont he same network, the data link frame is sent directly to the receiving device - on an ethernet network, data link addresses are known as Ethernet Media Access Control (MAC) addresses **MAC (Media Access Control) addresses** - are physically embedded on the ethernet NIC - cannot be changed **types** - source MAC address - Ethernet MAC address of the sending device - destination MAC address - when the receiving device is on a different network, the sending device will use the ethernet MAC address of the default gateway or router **Data link (layer 2) addresses** - purpose is of the data link address is to deliver the data link address is to deliver the data link frame from one network interface to another network interface on the same network - before an IP packet can be sent over a wired or wireless network, it MUST BE ENCAPSULATE IN A DATA LINK FRAME, so it can be transmitted over the physical medium **IP packet is encapsulated in a data link frame that contains the following information** - Source data link address - physical address of the NIC (sender) - Destination data link address - physical address of the NIC (receiver). **CHAPTER 4: Physical Layer** - the first layer of the OSI Model. - It transports bits across the network media. - This layer is the last step in the encapsulation process. **Network Interface Card (NIC) --** it is a hardware component that allows a computer or device to connect to a network, typically a Local Area Network (LAN) or the internet. **3 Functional Areas of a Physical Layer Standards** - **Physical Components --** are the hardware devices, media and connectors that transmits the signals that represents bits. - **Encoding --** this converts the stream of bits into a format recognizable by the next device in the network path. - **Signaling --** is how the bit values, "1" and "0" are represented on the physical medium. **Bandwidth --** is the capacity at which medium can carry data. - **Bandwidth Terminologies** - **Latency --** amount of time for data to travel from one given point to another. - **Throughput --** the measure of the transfer of bits across the media over a given period of time. - **Goodput --** the measure of usable data transferred over a given period of time. **COPPER CABLING** - This is the most common type of cabling used in networks today. - Inexpensive and easy to install, and has low resistance to electrical current flow. **Limitations of Copper Cabling** - **Attenuation --** the longer the electrical signals have to travel, the weaker they get. - **Electromagnetic Interface (EMI) --** it is the disruption or disturbance that an external electromagnetic field causes in an electronic device or system. - **Radio Frequency Interface (RFI) --** it can interfere with the proper functioning of radio communication devices, including televisions, radios, cell phones, Wi-Fi networks, and other wireless systems. - **Crosstalk -** this occurs when a signal transmitted in one channel or wire causes disturbances in another nearby channel, leading to degraded signal quality, noise, or data corruption. Crosstalk is common in communication systems that use electrical signals, such as telephone lines, Ethernet cables, or audio systems. **3 Types of Copper Cabling** - **Unshielded Twisted-Pair (UTP) --** most common networking media - **Shielded Twisted-Pair (STP) --** More expensive, harder to install, and better protection than UTP. - **Coaxial Cable --** this commonly used in wireless installations and cable internet connections. **UTP Cabling** - It has a four pairs of color-coded copper wires twisted together and encased in a flexible plastic sheath. **Fiber-Optic Cabling** - This transmits data over longer distances at higher bandwidth than any other networking media. This cabling is less susceptible to attenuation, and completely immune to **EMI/RFI.** - This also uses a laser or LED to encode bits as pulses of light. **Two Types of Fiber Media** - **Single Mode Fiber** - **Multi-mode Fiber** **Four Types of Industry that uses Fiber-optic cabling** - **Enterprise Networks --** used for backbone cabling applications and interconnecting infrastructure devices. - **Fiber-to-the-Home (FTTH)** -- used to provide always-on broadband services to homes and small businesses. - **Long-Haul Networks --** used by service providers to connect countries and cities. - **Submarine Cable Networks --** used to provide reliable high-speed, high-capacity solutions capable of surviving in harsh undersea environments at up to transoceanic distances. **Wireless Media** - Electromagnetic signals representing binary digits using radio or microwave frequencies. **Limitations** - **Coverage area** - **Interference** - **Security** - **Shared medium** **Types of Wireless Media / Wireless Standards** - **Wi-Fi (IEEE 802.11) --** Wireless LAN Technology - **Bluetooth (IEEE 802.15) --** Wireless Personal Area network (WPAN) standard - **WiMAX (IEEE 802.16) --** Uses a point-to-multipoint topology to provide broadband wireless access. - **Zigbee (IEEE 802.15.4) --** Low data-rate, low power-consumption communications, primarily for IoT applications. **In WLAN this requires the following:** - **Wireless Access Point --** concentrate wireless signals from users and connect to the existing copper-based network infrastructure. - **Wireless NIC Adapters --** provide wireless communications capability to network hosts. **CHAPTER 6: Data Link Layer** - Second to the last layer in OSI Model. - This layer is responsible for communications between end-device network interface cards. - This layer also performs error detections and rejects corrupts frames. **The Two Sub-Layer of Data Link (Most Important Part of this Layer)** - **LLC Sublayer** -- also known as **Logical Link Control,** is responsible for managing and maintaining the logical links between devices over a network. It handles error detection, flow control, and synchronization of data frames, ensuring the correct delivery of data between the source and the destination. (Upper Layer). - **MAC Sublayer** -- **Media Access Control,** is responsible for data encapsulation and MAC. (Lower Layer). **Data Link Layer Standards** **Some engineering organizations:** - **IEEE -- Institute for Electrical and Electronic Engineers** - **ITU -- International Telecommunications Union** - **ISO -- International Organizations for Standardization** - **ANSI -- American National Standards Institute** **TOPOLOGIES** **WAN TOPOLOGIES** - **Point-to-point --** the simplest and most common WAN topology. Consists of a permanent link between two endpoints. - **Hub and spoke --** similar to a star topology where a central site interconnects branch sites through point-to-point links. - **Mesh** -- provides high availability but requires every end system to be - connected to every other end system. **LAN TOPOLOGIES** - **Bus --** All end systems chained together and terminated on each end. - **Ring --** Each end system is connected to its respective neighbors to form a ring. **Two Types of Duplex Communication** - **Half-duplex communication --** can only send or receive at a time. - **Full-duplex communication --** can send and receive at the same time. **CHAPTER 7: Ethernet Frames** - This frame operates in the **Data link layer** and the **Physical Layer.** - It is also a family of networking technologies defined in the IEEE 802.2 and 802.3 standards. **Data Encapsulation** - IEEEE 802.3 data encapsulation includes the ff: - **Ethernet frame --** this is structure of the ethernet frame. - **Ethernet Addressing --** the ethernet frame includes both a source and destination MAC address to deliver the Ethernet frame from Ethernet NIC to Ethernet NIC on the same LAN. - **Ethernet error detection --** The Ethernet frame includes a frame check sequence (FCS) trailer used for error detection. - The minimum Ethernet frame size is **64 bytes** and the maximum is **1518 bytes**. The preamble field is not included when describing the size of the frame. - Any frame less than 64 bytes in length is considered a "**collision fragment**" or "**runt frame**" and is automatically discarded. Frames with more than 1500 bytes of data are considered "**jumbo**" or "**baby giant frames**". - If the size of a transmitted frame is less than the minimum, or greater than the maximum, the receiving device drops the frame. Dropped frames are likely to be the result of collisions or other unwanted signals. They are considered invalid. Jumbo frames are usually supported by most Fast Ethernet and Gigabit Ethernet switches and NICs. **Ethernet MAC Address** - In an Ethernet LAN, every network device is connected to the same, shared media. MAC addressing provides a method for device identification at the data link layer of the OSI model. - An Ethernet MAC address is a 48-bit address expressed using 12 hexadecimal digits. Because a byte equals 8 bits, we can also say that a MAC address is 6 bytes in length. **Frame Processing** - When a device is forwarding a message to an Ethernet network, the Ethernet header include a Source MAC address and a Destination MAC address. - When a NIC receives an Ethernet frame, it examines the destination MAC address to see if it matches the physical MAC address that is stored in RAM. If there is no match, the device discards the frame. If there is a match, it passes the frame up the OSI layers, where the de-encapsulation process takes place. - Any device that is the source or destination of an Ethernet frame, will have an Ethernet NIC and therefore, a MAC address. This includes workstations, servers, printers, mobile devices, and routers. **TYPES OF DELIVERY OPTIONS IN ETHERNET MAC ADDRESS** **Unicast MAC Address** - A unicast MAC address is the **unique address that is used when a frame is sent from a single transmitting device to a single destination device**. **Broadcast MAC Address** - It has a destination MAC address of **FF-FF-FF-FF-FF-FF** in hexadecimal (48 ones in binary). - It is flooded out all Ethernet switch ports except the incoming port. It is not forwarded by a router. **Multicast MAC Address** - An Ethernet multicast frame is received and processed by a group of devices that belong to the same multicast group. - There is a destination MAC address of **01-00-5E** when the encapsulated data is an **IPv4 multicast packet** and a destination MAC address **of 33-33** when the encapsulated data is **an IPv6 multicast packet**. - There are other reserved multicast destination MAC addresses for when the encapsulated data is not IP, such as **Spanning Tree Protocol** (STP). - **It is flooded out all Ethernet switch ports except the incoming port**, unless the switch is configured for multicast snooping. It is not forwarded by a router, unless the router is configured to route multicast packets. - Because **multicast addresses represent a group of addresses** (sometimes called a host group), they can only be used as the destination of a packet. The source will always be a unicast address. - As with the unicast and broadcast addresses, **the multicast IP address requires a corresponding multicast MAC address**. **Forwarding Methods on Cisco Switches** - **Store-and-forward switching -** This frame forwarding method receives the entire frame and computes the CRC. If the CRC is valid, the switch looks up the destination address, which determines the outgoing interface. Then the frame is forwarded out of the correct port. - **Cut-Through Switching -** the switch acts upon the data as soon as it is received, even if the transmission is not complete. The switch buffers just enough of the frame to read the destination MAC address so that it can determine to which port it should forward out the data. The switch does not perform any error checking on the frame. **Two Variants of Cut-Through Switching:** - **Fast-forward switching --** this has no checking on the bits/bytes of the packet. - **Fragment-free switching --** reads and checks the first 64 bytes of the packet. **Auto MDIX (Medium Dependent Interface Crossover)** - This allows devices to automatically detect and switch the transmission and receiving pins. **CHAPTER 8: NETWORK LAYER** - The main function of this layer is to provide / read IP Addressing in a packet. **Network Address Translation (NAT)** - is a method used in networking to map multiple private IP addresses to a single public IP address (or a few public IPs). It\'s commonly used in routers to allow devices within a local network to access the internet using a single public IP address, while still being identified uniquely within the local network. **Four basic operations of Network Layer** - **Addressing end devices** - **Encapsulation** - **Routing** - **De- Encapsulation** **Characteristics of an Internet Protocol** - **Connectionless** - **Best Effort** - **Media Independent** **IPv4 Packet** - It is in binary, and contains several fields of information. - The diagram is read from left to right, 4 bytes per line. - The two most important fields are the **source** and **destination.** **Limitations of IPv4** - IPv4 address depletion, we basically run out of IPv4 addressing, lack of end-to-end connectivity, and increased network complexity. **Significant Fields of IPv4:**  **IPv6 Packet** - **IPv6** is developed by the **Internet Engineering Task Force (IETF).** - This version was made because of the limitations of IPv4. - This version also overcomes the limitations of IPv4. **Some improvements that IPv6 provides:** - **Increased address space --** based on 128 bits address, not 32 bits - **Improved packet handling** --simplified header with fewer fields - **Eliminates the need for NAT** -- since there is a huge amount of addressing, there is no need to use private addressing internally and be mapped to a shared public address. **Significant Fields of IPv6:** **Default Gateway** - refers to the router or Layer 3 device that a network device (such as a computer or switch) uses to send data to a destination outside its own local subnet. It\'s essentially the IP address of the router interface on the local network that forwards packets to other networks, typically towards the internet.  **Introduction to Routing** What happens when the router receives the frame from the host device? - The router receives the frame and verifies the destination MAC. - It strips the Layer 2 header and inspects the IP packet. - The router makes a routing decision based on the destination IP address. - The router creates a new frame for forwarding, with updated MAC addresses. - The frame is forwarded toward the next hop or the destination device. **Three Types of Routes in a Routing Table** - **Directly Connected --** These routes are automatically added by the router, provided the interface is active and has addressing. - **Remote --** These are the routes the router does not have a direct. connection and may be learned: ** Manually --** with a static route ** Dynamically --** by using a routing protocol to have the routers share their information with each other. - **Default Route --** this forwards all traffic to a specific direction when there is not a match in the routing table. **Two types of Routing** - **Static Routing -** is a routing method where routes are manually configured by the network administrator, rather than being learned dynamically through routing protocols. - **Dynamic Routing -** is a method where routers automatically learn and adjust routes based on real-time changes in the network topology, using routing protocols. **IP Routing Table** ** L -** Directly connected local interface IP address ** C --** Directly connected network ** S --** Static route was manually configured by an administrator ** O --** OSPF (Open Shortest Path First) ** D** -- EIGRP (enhanced interior gateway routing protocol) **TAPOS!!! PASADONG MIDTERMS PLSS!!** **gawa ni joms mwheheehe**