Chapter 2

BaseBand

Baseband is a signal that has a very narrow frequency range, i.e. a spectral magnitude that is nonzero only for frequencies in the vicinity of the origin (termed f = 0) and negligible elsewhere.

layer 2 switch

Determines the path for data used in the MAC address.

layer 3 switch

Determines the path for data used ip address.

MAC Flood

In computer networking, MAC flooding is a technique employed to compromise the security of network switches. Switches maintain a MAC Table that maps individual MAC addresses on the network to the physical ports on the switch.

ports

In computer networking, a port is an endpoint of communication in an operating system. While the term is also used for hardware devices, in software it is a logical construct that identifies a specific process or a type of service.

ARP table

In an Ethernet local area network, however, addresses for attached devices are 48 bits long. (The physical machine address is also known as a Media Access Control or MAC address.) A table, usually called the ARP cache, is used to maintain a correlation between each MAC address and its corresponding IP address

transport layer

In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet Protocol Suite and the Open Systems Interconnection (OSI). The protocols of the layer provide host-to-host communication services for applications.

overhead

In computer science, overhead is any combination of excess or indirect computation time, memory, bandwidth, or other resources that are required to attain a particular goal. It is a special case of engineering overhead.

presentation layer

It is used to present data to the application layer (layer 7) in an accurate, well-defined and standardized format. The presentation layer is sometimes called the syntax layer.

CAM Table

The CAM table is one of the fundamental operations of a switch. It's not only important for the 642-813 SWITCH exam but it's important to know for working on the job. The CAM table, or content addressable memory table, is present in all Cisco Catalysts for layer 2 switching.

communications subnetwork

The communications subnetwork is the guts of OSI model transmissions, consisting of layers 1 through 3. Regardless of what type of data transmission occurs in a computer network, the communication subnetwork will be employed.

data link layer (DLL)

The data link layer or layer 2 is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between adjacent network nodes in a wide area network (WAN) or between nodes on the same local area network (LAN) segment.

physical layer

The physical layer deals with bit-level transmission between different devices and supports electrical or mechanical interfaces connecting to the physical medium for synchronized communication.

protocol stack

The protocol stack is an implementation of a computer networking protocol suite. The terms are often used interchangeably. Strictly speaking, the suite is the definition of the protocols, and the stack is the software implementation of them.

session layer

The session layer provides the mechanism for opening, closing and managing a session between end-user application processes, i.e., a semi-permanent dialogue.

outbound ports

Used to connect to a service or application used by another computer.

inbound ports

Used to connect to a service or application used by your computer.

BroadBand

a high-capacity transmission technique using a wide range of frequencies, which enables a large number of messages to be communicated simultaneously.

Internet Assigned Numbers Authority (IANA)

a nonprofit private American corporation that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Internet Protocol-related symbols and numbers.

Internet Protocol

a set of rules governing the format of data sent over the Internet or other network.

Ethernet

a system for connecting a number of computer systems to form a local area network, with protocols to control the passing of information and to avoid simultaneous transmission by two or more systems.

Media Access Control (MAC) address

also called physical address, is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used as a network address for most IEEE 802 network technologies, including Ethernet and WiFi.

encoded

convert into a coded form.

encapsulated

enclose (a message or signal) in a set of codes that allow use by or transfer through different computer systems or networks.

User Datagram Protocol (UDP)

is an alternative communications protocol to Transmission Control Protocol (TCP) used primarily for establishing low-latency and loss tolerating connections between applications on the Internet.

virtual LAN (VLAN)

is any broadcast domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2). LAN is an abbreviation of local area network. To subdivide a network into virtual LANs, one configures a network switch or router.

Internet Control Message Protocol

is one of the main protocols of the internet protocol suite. It is used by network devices, like routers, to send error messages indicating, for example, that a requested service is not available or that a host or router could not be reached.

Open Systems Interconnection (OSI)

is reference model for how applications can communicate over a network. A reference model is a conceptual framework for understanding relationships.

Internet Engineering Task Force (IETF)

is the body that defines standard Internet operating protocols such as TCP/IP. The IETF is supervised by the Internet Society Internet Architecture Board (IAB). IETF members are drawn from the Internet Society's individual and organization membership.

Address Resolution Protocol

protocol used by the Internet Protocol (IP) [RFC826], specifically IPv4, to map IP network addresses to the hardware addresses used by a data link protocol. The protocol operates below the network layer as a part of the interface between the OSI network and OSI link layer.

Transmissions Control Protocol

standard that defines how to establish and maintain a network conversation via which application programs can exchange data. TCP works with the Internet Protocol (IP), which defines how computers send packets of data to each other.