IT2203 Routing Fundamentals: Data Encapsulation

Address Resolution Protocol (ARP)

• Obtains the physical address of a node from a specific IP number
• Dynamically binds a high-level IP address to a low-level physical hardware address
• Limited to networks that support hardware broadcast

Reverse Address Resolution Protocol (RARP)

• Allows a host with no local permanent data storage media to find its Internet address given its physical address

Common Network Access Layer Protocols

• Ethernet: a family of LANs, covered by IEEE 802.3 standards, uses a CSMA/CD access method
• Point-to-Point Protocol (PPP): used for data transfer across a serial line
• Fiber Distributed Data Interface (FDDI): a set of ANSI protocols for sending digital data over fiber optic cable
• Asynchronous Transfer Mode (ATM): a wide area protocol with high data rates and equal-sized packets/cells
• Frame Relay: a WAN protocol for LAN internetworking, provides fast and efficient method of transmitting information
• Proxy ARP: used when a network terminal needs to pass data from one segment to another without changing its current IP address information

Packet Forwarding and Delivery

• Packet forwarding: passing or moving of information between interfaces according to "directions"
• Packet delivery: the way a packet is handled by the underlying physical networks
• Direct delivery: occurs when the IP node forwards a packet to its final destination in the network
• Indirect delivery: occurs when the IP node forwards a packet to an intermediate node (IP router) because the final destination is not on a directly attached network

Routing Table

• A database that contains information about which router network interface or port to place information to send it to a particular network segment
• Destination/Mask: indicates the destination network address and mask of a specific route
• Example: destination address is 1.1.1.1 and the mask is 255.255.255.0, the IP address of the subnet to which the host or router belongs is 1.1.1.0

Routing Fundamentals

• Routing: the process of selecting paths on a network along which packets are sent from a source to a destination
• Path determination: enables a router to compare the destination address to the available routes in its routing table and to select the best path
• Routes: the path information used to guide packet forwarding
• Routing device (Router): a network device that forwards packets to a destination subnet based on routes
• Routing table: stores routing information

Route Components

• Destination: identifies a destination subnet
• Mask: identifies a subnet together with a destination IP address
• Outbound interface: indicates the interface through which a data packet is sent out of the local router
• Next hop: indicates the next-hop address used by the router to forward the data packet to the destination subnet

Data Encapsulation and Decapsulation

• Encapsulation: a process wherein a new string of information is added to an existing unit to form a new unit of information
• Decapsulation: the reverse process of encapsulation, wherein the header and tail of a packet are removed to obtain the data payload

TCP Protocol Data Units

• Protocol Data Unit (PDU): a specific block of information transferred over a network
• Protocol (Proto): indicates the protocol type of the route
• Preference (Pre): indicates the routing protocol preference of the route
• Cost: indicates the cost of the route
• Next Hop: indicates the local router’s next-hop address of the route to the destination network
• Interface: indicates the outbound interface of the route

This quiz covers the concepts of data encapsulation and decapsulation in network communication, including the process of adding headers and trailers to form a new unit of information.