Network Tech prefi

Encapsulation

is a process wherein a new string of information is added to an existing unit to form a new unit of information.

Decapsulation

is the reverse process of encapsulation wherein the header and tail of a packet are removed to obtain the data payload.

Packet

is a data unit that is exchanged and transmitted on a network. It is in the format of header+data payload+tail. During transmission, the format and content of packets may change.

Header

is the information segment added before the data payload during packet assembly to facilitate information transmission.

Tail

is the information segment added after the payload to facilitate information transmission.

Protocol Data Unit (PDU)

is a specific block of information transferred over a network. It is often used in reference to the OSI model, since it describes the different types of data that are transferred from each layer.

• Physical layer

raw bits (1s or 0s) transmitted physically via the hardwa

Data Link layer

a frame (or series of bits)

Network layer

a packet that contains the source and destination address

Transport layer

a segment that includes a TCP header and data

Session layer

the data passed to the network connection

Presentation layer

the data formatted for presentation

Application layer

the data received or transmitted by a software application

Internet Protocol (IP)

-Defines a packet and an addressing scheme

-Transfers data between the Internet layer and network access layers

-Routes packets to remote hosts

Internet Control Message Protocol (ICMP)

It refers to a TCP/IP protocol that handles errors and controls the process of sending data between computers.

Internet Group Management Protocol (IGMP)

: It refers to a TCP/IP protocol that handles multicasting. Hosts use IGMP to keep local routers apprised of their membership in multicast groups.

Address Resolution Protocol (ARP):

It refers to a TCP/IP protocol that obtains the physical address of a node from a specific IP number.

Reverse Address Resolution Protocol (RARP):

It refers to a TCP/IP protocol that allows a host with no local permanent data storage media to find its Internet address given its physical address.

• Ethernet

: It refers to a family of LANs, covered by a group of IEEE 802.3 standards. Ethernet is a best-effort delivery system that uses a CSMA/CD access method.

Point-to-Point Protocol (PPP):

This refers to the protocol used for data transfer across a serial line.

Fiber distributed data interface (FDDI):

This is a set of ANSI protocols for sending digital data over fiber optic cable

Asynchronous Transfer Mode (ATM):

This refers to a wide area protocol that features high data rates and equalsized packets/cells suitable for text, audio, and video data transfer

Frame Relay:

This is a WAN protocol for LAN internetworking that provides a fast and efficient method of transmitting information from one user device to another across multiple switches and routers.

Proxy ARP:

This protocol is used when a network terminal needs to pass data from one segment to another without changing its current IP address information.

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

are the path information used to guide packet forwarding.

routing device (Router)

is a network device that forwards packets to a destination subnet based on routes. It maintains an IP routing table that stores routing information

Packet routing

is the overall network-wide process of finding the most efficient path for forwarding the IP packet from source to destination through the use of network routing tables, protocols, and algorithms.

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.

Packet Forwarding

it is simply a passing or moving of information between interfaces (which can be from a host/router to the final destination/intermediate connecting device) according to the “directions”

Packet Delivery

refers to the way a packet is handled by the underlying physical networks under the control of the network layer

Direct Delivery

occurs when the IP node forwards a packet to its final destination in the network.

Indirect Delivery

occurs when the IP node (host) forwards a packet to an intermediate node (IP router) because the final destination is not on a directly attached network.

Direct routes

are automatically generated by devices and point to local directly connected networks. These are the routes destined for the subnets to which directly connected interfaces belong.

Static routes

are manually configured by network administrators. This can be an effective method for networks with small and simple structures and reduce the effect of bandwidth and CPU resource consumption that occurs when other protocols are implemented.

Dynamic routes

are learned by dynamic routing protocols running on routers. This route uses routing protocols to talk to other routers and find out what networks they are attached to.