ITS-101: Glossary Flashcards
Access Devices
Access devices are those that connect directly to field level devices. In most cases, this refers to switches that are in IDFs and connected directly to devices such as panels, DXRs, and workstations. Access devices are usually cheaper and have fewer features than core devices.
Balance Twisted Pair Cabling
Data network cabling, sometimes loosely referred to as “Category 6” or “Copper” cable, is used to provide connectivity between network equipment. Data network cabling typically utilizes metallic conductor cables with a balanced twisted-pair construction. As such, standards typically refer to this cabling as “Balanced Twisted Pair” cable. In this cable, the conductors, most often made of copper, are twisted to minimize crosstalk and noise between the pairs, while improving the overall data transmission performance. Balanced twisted pair cables typically support lower bandwidths than optical fiber cabling. Performance of Balanced twisted-pair cables is directly related to the length of the cable and is therefore limited to shorter distances, most often 90 m (295 ft).
Bonding / EtherChannel
Bonding, also referred to as EtherChannel, takes the idea of redundancy a step further. Spanning Tree Protocol/Rapid Spanning Tree Protocol provide the ability to add redundancy by disabling secondary links that would cause a loop. Bonding gives the same redundancy, but accomplishes this by combining multiple links, presenting them to the network as one link. Bonding has the major benefit of providing redundancy, as well as increasing the available bandwidth. For example, if we combine two 1 gigabit links, we will have a single logical 2 gigabit link.
Bounding Device
Defines the edge of a network segment. For both layer 2 and layer 3 segments, the bounding device that defines the physical edge of the segment is a router. For layer 2 segments, the router is a bounding device because it does not forward traffic with the MAC address intact, so devices cannot communicate across a router using MAC addresses alone. For layer 3 segments, a router is where traffic is sent when the destination IP address is not on the subnet, so devices cannot communicate across a router directly.
Broadcast Network Traffic
Sent to a special broadcast IP address (the last IP address in a subnet) and every device on a subnet listens for and receives traffic sent to the broadcast address. Switches will always send broadcast traffic out all connected switchports. Routers block broadcasts.
Building System Network Characteristics
Characteristics define key aspects of the network requirements and inform major design decisions. The 8 main network characteristics used by Siemens network designers are: Project: Size, Project: Network Equipment Type, Logical: Externally connected, Logical: Segmentation / VLANs required, Physical: Horizontal topology, Physical: Vertical topology, Physical: IDF topology, Physical: IDF density
CIDR
A shortcut format for writing subnet masks. CIDR is written right after an IP address (on the same line) and starts with a slash (/) followed by a number between 0 and 32. The larger the number, the smaller the subnet and the fewer IP addresses in the contiguous range. Every subnet mask expressed in dotted-decimal notation has a corresponding CIDR shortcut. For instance, “/24” is a common CIDR subnet mask that corresponds to 255.255.255.0.
Collision Domain
A network segment where traffic from connected devices will electronically (or optically) collide. Any physical medium that propagates electrical signals sent to all devices and where only one device can send at a time is a collision domain.
Console Access
A method of accessing a network device (switch, router, firewall, etc.) that works even when the device is not operating properly and usually allows for configuration of all functionality. Misconfiguration or mistakes with low level console access can damage the device.
Console Cable
A physical cable that connects a laptop or workstation to the console port on a network device and allows console access.
Core devices
Core devices are usually located in the MDF, and connect all the access devices together. Core devices are frequently more expense than access devices and support additional features, such as redundancy and dual power supplies.
Domain Name System (DNS)
The Domain Name System (DNS) is a system used to convert a computer’s host name into an IP address. A simple example of this is how we interact with the internet every day. When www.siemens.com is entered into a web browser, we are taken to the Siemens website hosted on Siemens servers. In the background, www.siemens.com is translated into an IP address by a DNS server that tells our device how to get there.
Dotted-Decimal
A format for writing subnet masks composed of 4 groups of numbers separated by periods. For example, 255.255.255.0 is a common subnet mask written in dotted-decimal notation.
Downlink or Access Port
Downlink or access ports are the physical ports on a switch that are connected directly to field level devices. Downlink/access ports frequently operate at slower speeds than uplink ports.
Duplex Negotiation
The process where a network device and network equipment determine via a mutual exchange of pre-specified traffic whether each device supports Full-Duplex communications or whether Half-Duplex must be used.
Dynamic Host Configuration Protocol (DHCP)
Dynamic Host Configuration Protocol (DHCP) is a protocol for assigning IP addresses dynamically to devices on a network. Dynamic addressing simplifies network administration because the software keeps track of IP addresses rather than requiring an administrator to manage the task. This means that a new computer can be added to a network without the hassle of manually assigning it a unique IP address.
Firewall
A firewall selectively blocks and allows network traffic based on source / destination IP address and type of traffic. The administrator can configure policies to allow only desired traffic. Firewalls should always be located between trusted and untrusted networks (such as the internet).
Full-Duplex
A physical connection and device functionality that allows for bi-directional communication between two devices without traffic colliding. Full-Duplex devices connected to network equipment (such as switches) that support Full-Duplex have dedicated wire(s) to send and receive, eliminating the possibility of collision.
Half-Duplex
A physical connection and device functionality that only allows one device to communicate at a time.
Horizontal Cabling
Connects floor-level devices (controllers, panels, workstations, etc.) to the nearest network equipment (usually in an IDF). Is most frequently balanced twisted pair (copper), but can occasionally be fiber optic cabling.
Hub
A legacy type of network device that connects devices, but doesn’t prevent traffic from colliding. Hubs are slow and create errors.
Intermediate Distribution Frame (IDF)
Intermediate Distribution Frame (IDF) is a room where network equipment is mounted, and where the cables going to field level devices are terminated.
IP Address
Internet Protocol addresses are configured on network devices. When a device sends traffic across the network it uses the IP address of the destination device to ensure that routers know how to get the traffic to the right network.
IP Subnet
A contiguous grouping of IP addresses that can communicated directly. Devices connected to the same subnet receive broadcast traffic sent by any device on the subnet.
Layer 2 and Layer 3 Segment Overlap
There should always be one layer 3 segment (subnet) per layer 2 segment (physically connected group of devices). Overlapping can occur if devices in the same physically connected group (e.g. attached to the same switch) are assigned IP addresses in different subnets. Overlapping layer 3 and layer 2 segments can lead to major performance issues.
Layer 2 Segment
Any collection of devices that are physically connected where devices can communicate directly with each other using MAC addresses.
Layer 3 Segment
A collection of devices that have been assigned IP addresses in a contiguous range (subnet) with a defined starting and ending address.
LC connectors
LC Connectors are popular due to their small form factor and high-performance ratings. Two single (simplex) LC connectors can be clipped together to form a duplex connector. Most SFP Optical Transceivers utilize Duplex LC type connectors.
Least Privilege
The concept of providing only the minimum privileges to a user account that are required for that account to perform critical job functions. The concept is applicable to applications, operating systems, building system devices, and any other situations where permissions can be configured. One of the most common applications of least privilege is ensuring that a normal user account on a workstation is not an administrator.
Logical Network Topology
Show how network traffic flows across the physically connected devices that make up the network. Details such as segmentation, routing, and how firewalls allow or block traffic are included on a logical network topology.
