Network Engineering & Operations
online resources for network services
 

Network Terminology

Network Engineering & Operations is the group within ITS responsible for connecting users and groups to University of Colorado network resources and the Internet. This involves cabling, switches, routers, subnets, IP addressing, DNS, wireless networks, off-campus access, and more.

ACTIVE ETHERNET JACK - An Ethernet jack is active when it is connected to the University network. A jack can be wired, but will not have network service until it is connected to ITS network equipment. See also ETHERNET JACK, PORT.

ACTIVATE AN ETHERNET JACK - Order Ethernet service to be installed (connected) on a jack. A department telecommunications liaison or computing support representative submits an order, a work order is written by ITS and a CU technician connects the jack wiring to a network switch. The switchport is enabled and set to the correct speed and subnet. See also ETHERNET JACK, PORT.

ADDHOST DATABASE - The CU-Boulder database that contains information about IP addresses, hostnames and computers connected to the network. The DNS tables for campus are rebuilt nightly with information contained in the addhost database. From any Colorado.edu host, the addhost data can be browsed/searched at hippo.colorado.edu/iplookup/. See also HIPPO, DNS.

ALLIANCE NETWORK - Data communication networks managed and operated by a department independently from the centrally supported and managed networks. In a typical situation, the department provides the networking infrastructure, including wiring and data communication switches and human support. The data communication switches connect to the campus network maintained by ITS to provide network access. Departments pay monthly charges per host for network usage. See Ethernet rates at www.colorado.edu/its/networking/rates.html

B-JACK - See ETHERNET JACK.

BLOCKED HOST - If a campus host (device) is found to be participating in harmful network behavior, this host can be restricted from access to the network. It is often the result of having vulnerable (unpatched) operating systems infected by malicious programs. An affected user should contact the IT Help Desk (5-HELP) to resolve the problem. A list of blocked hosts can be found at blockedhosts.colorado.edu/. See also www.colorado.edu/its/security/. See also HOST

CATEGORY 3/5/6 WIRING - The type of twisted pair copper cabling used in phone and data networks to connect a device to a jack, and the cabling used in the ceilings/walls to connect the jack to the local equipment closet. Different category cable supports different network connection speeds - generally, the higher the value, the faster the service. A network connection is only as fast as its slowest link. Category 3 wiring can carry a maximum rate of 10 Mbps (megabits per second), category 5 can support Fast Ethernet (up to 100 Mbps), category 5e and 6 have the potential to carry Gigabit (1000 Mbps) service. Category 6 wiring is currently the standard for new data jack installations except in a limited number of locations on campus that currently cannot support it. Outlet color indicates wiring: beige is category 3 wiring, black is category 5 wiring, blue is category 6 wiring.

COMPUTING SUPPORT REPRESENTATIVE (CSR) - The person identified by each department who acts as a liaison to ITS regarding computing and networking support. Tier II of the ITS customer support model.

DENIAL-OF-SERVICE (DOS) ATTACK - Occurs when an overwhelming number of requests are sent to a server or other device, either from a single attacking computer or spread across multiple attacking computers, which causes legitimate users to be rejected from the server or the server to crash. Vulnerable (unpatched) operating systems can be used by malicious programs to participate in DOS attacks unknowingly.

DHCP - Dynamic Host Configuration Protocol. A means to allow a device to automatically obtain TCP/IP settings needed to connect to the network. This alleviates the need to manually enter any network settings (such as IP address) into the device. Since IP addresses are a limited commodity, DCHP allows addresses to be used more efficiently: if a device is turned off for a period of time, the IP address is not needed and is returned to the available pool of addresses. When the device is turned back on, it may not have the same address, but it will obtain another valid address from the DHCP server. For further information, see hippo.colorado.edu/info/dhcp/. See also IP ADDRESS, STATIC IP ADDRESS.

DNS - Domain Name System (or Service) translates Internet domain and host names (such as spot.colorado.edu, or cnn.com) to IP addresses and vice versa. In manual TCP/IP configurations (static IP addresses), the IP addresses of at least two local nameservers should be entered for DNS settings. For CU DNS server addresses, see hippo.colorado.edu/info/dns/. See also STATIC IP ADDRESS.

DOMAIN NAME - A unique name that identifies an Internet site. Has two or more parts separated by dots. CU Boulder's domain is 'colorado.edu'.

DUPLEX - In telecommunications, both ends of the communication can send and receive signals at the same time - this is full-duplex. Half-duplex is also bidirectional communication but signals can only flow in one direction at a time. Most modern network equipment can be set by ITS to run at half duplex, full duplex, or auto-negotiation (the hardware/software determines the best setting).

ENCRYPTION - To encode electronic communication so it is private. See www.colorado.edu/its/security.

ETHERNET - The most widely used local area network architecture. It is, essentially, what the UCB LAN runs on. The CU campus data network runs on Ethernet at speeds of 10 Mbps (also known as 10 base-T), 100 Mbps (100 base-T) and 1000 Mbps (Gigabit). See also LAN.

ETHERNET ADDRESS - The unique serial number associated with a network interface card (NIC) in a computer or other device. Also known as MAC (Media Access Control) address, hardware address, node ID, physical address or adapter address. A network card transmits its address with each packet of data, so it acts as a signature or fingerprint of the computer. It is a 6-byte hexadecimal number represented by 12 hex digits. Each digit must be a number between 0 and 9 or a letter between A and F (Example: 00:40:05:1c:0e:9f ). See also hippo.colorado.edu/info/hwaddress/.

ETHERNET JACK - Also known as b-jack, data jack or wall outlet; the jack that a device must be plugged into to access the network. Telephone equipment normally (but not always) occupies the "A" outlet, network equipment is usually connected to the "B" outlet. Sometimes the outlets on the jack faceplate are labeled 1, 2, 3, but are still referred to as A, B, etc. for ITS purposes. See also CATEGORY 3/5/6 WIRING.

FAST ETHERNET - Ethernet that operates at up to 100 Mbps (megabits per second). Also known as 100-base TX. Requires category 5 or higher wiring. See also ETHERNET.

GATEWAY - The device that local subnet traffic must go through to reach the outside world, usually this is a router. Static IP address settings must include the IP address of the subnet gateway or router. See also TCP/IP, ROUTER, STATIC IP ADDRESS.

HARDWARE ADDRESS - See ETHERNET ADDRESS

HIPPO - Helpful IP Print Outs. A collection of networking tools and reports developed by ITS. See hippo.colorado.edu/.

HOST - Any addressable device connected to a TCP/IP network.

HOSTNAME - The unique name by which a host (a computer or other device) is known on a network, followed by the domain name. Associated with a specific IP address but easier to remember. Examples of hostnames: spot.colorado.edu, amazon.com. A computer may be known by more than one name, called aliases.

IP - Internet Protocol. See TCP/IP.

IP ADDRESS - A unique number given to every device on the Internet. This number enables traffic to be delivered from one host to another. If two devices are configured to use the same IP address, an IP conflict occurs and one or both will lose network access, sometimes intermittently. Most users will obtain their IP addresses automatically by using DHCP. See also DHCP, STATIC IP ADDRESS.

JACK - The outlet (faceplate) where phone and data cables are plugged into phone and data outlets. Each outlet is technically a jack with its own monthly charges if active, but the faceplate is often referred to as a jack as well. All CU faceplates are labeled with a number, usually 3 groups of numbers and letters separated by dashes. Each outlet is given a letter designation: first port is A, second is B, etc. See also ETHERNET JACK.

LAN - Local Area Network. A group of computers and other network devices connected to each other in the same physical location.

MAC ADDRESS - See ETHERNET ADDRESS

MBPS - Megabits per second. Measurement of data transfer rate.

PORT - Point where an active Ethernet jack is connected to a network switch. Wires running from the jack in an office are connected to a network switch located in a telecommunications closet. Each active jack is connected to a switchport. Port numbers include the switch number and the port number - this allows for a unique port identification across campus, for example port U251013 is switch U2510, port 33. Jacks not connected to a switchport are not active. On ITS statements, this number is also referred to as "Extension." See also B-JACK.

ROUTER - A piece of networking equipment that analyzes network addresses and directs network traffic to its intended destination. See also STATIC IP ADDRESS.

STATIC IP ADDRESS - Static IP addresses on CU Boulder campus must be assigned by ITS or other designated network administrators. A static IP address must be manually entered into a device, along with router address, subnet mask, DNS server addresses and domain information. Unlike DHCP, the computer will always have the same (static) IP address. Static IP addresses are usually only necessary for servers, printers or devices that need to be remotely accessed. For the IP application, see hippo.colorado.edu/ipapp/. See also DHCP.

SUBNET - Short for "subnetwork," a segment of an organization's network. Most CU campus buildings are on different subnets, so a computer must have an IP address that is on the subnet served in that building on that jack, or use DHCP to automatically obtain a valid IP address for that location. A full subnet contains 256 addresses. Some subnets are broken into smaller segments containing 128, 64, 32 or fewer addresses. Each subnet has a different gateway or router address, and requires a subnet mask specific to the size of the subnet. See also DHCP, SUBNET MASK, TCP/IP.

SUBNET MASK - A required number entered in TCP/IP settings. Once a packet has arrived at an organization's gateway or router, it can be routed within the organization's internal gateways using the subnet number. The router knows which bits to look at (and which not to look at) by looking at a subnet mask. Using a mask saves the router having to handle the entire 32 bit address; it can simply look at the bits selected by the mask. From searchnetworking.techtarget.com/.

TCP/IP - Transmission Control Protocol/Internet Protocol. A set of protocols defining network communications and the addressing scheme. TCP establishes a virtual connection between a destination and a source. IP specifies the format of the data packets and the addressing scheme. The current version of IP is IP version 4 (IPv4). IPv6 is under development, and will coexist with IPv4 for some time. IPv6 will allow the Internet to grow, both in terms of the number of hosts connected and the total amount of data traffic transmitted. See also IP ADDESS.

TELECOMMUNICATIONS LIAISON - The person identified by each department who is responsible for orders and inventory of telecommunications services from ITS.

TIER II - SEE COMPUTING SUPPORT REPRESENTATIVE

VLAN - Virtual LAN. A method that allows a single physical network to be configured into multiple 'virtual networks.'

WIRELESS NETWORK - Networking without plugging a cable into an Ethernet jack; uses radio frequency signaling to communicate from hosts to access points connected to the wired network. The host must have a compatible wireless network card and be within range of a wireless access point in order to use the network. All users must authenticate on the wireless networks by providing IdentiKey and password. For locations of wireless networks, see www.colorado.edu/its/wireless/.

10-BASE-T - Ethernet (10 Mbps), the maximum speed that can be delivered over category 3 cabling. Can also be delivered on category 5, 5e, 6 cables. See also ETHERNET.

100-BASE-TX - Fast Ethernet (100 Mbps) can be delivered over category 5, 5e or 6 cabling. See also FAST ETHERNET.