CobraNet Glossary
100BASE-T
See Fast Ethernet.
1000BASE-T
See Gigabit Ethernet.
Audio Channel
A single audio signal. Audio channels on CobraNet have a 48KHz sampling rate and may be 16, 20 or 24 bit resolution. Multiple audio channels may be carried in a bundle.
Auto-negotiation
A low bit rate form of communication during which one device tells another device if it is capable of full- or half-duplex operation and whether to connect at 10MB or 100MB bit rates.
Broadcast Addressing
Broadcasting is a special case of Multicasting. Whereas it is possible, in some cases, to indicate intended recipients of multicast data, broadcast data is unconditionally received by all DTEs within a network domain.
Bundle
The basic network transmission unit under CobraNet. Up to 8 audio channels may be carried in a bundle.
Category 5 Cable (CAT5)
As used on this site, CAT5 is inexpensive unshielded twisted pair (UTP) data grade cable. It is very similar to ubiquitous telephone cable but the pairs are more tightly twisted. CAT5 cable runs are limited to 100 meters due to signal radiation and attenuation considerations. A CAT5 run in excess of 100 meters may be overly sensitive to electromagnetic interference (EMI). It should be noted that not all CAT5 cable is UTP. Shielded CAT5 also exists but is rare due to its greater cost and a much shorter distance limitations than UTP CAT5.
CobraNet®
CobraNet is a combination of hardware, software and protocol which distributes many channels of digital audio over Fast Ethernet. CobraNet supports switched and repeater Ethernet networks. On a repeater network, CobraNet eliminates collisions and allows full bandwidth utilization of the network. CobraNet uses standard Ethernet packets and network infrastructure.
CobraNet Device
A device in compliance with the CobraNet specification for transmission and/or reception of digital audio and associated sample clock.
Conductor
CobraNet Device on the network supplying master clock. A conductor arbitration procedure insures that at any time there is one and only one conductor per network.
Crossover Cable
A crossover cable can be used to directly connect two network devices.
DTE
Short for Data Terminal Equipment, a DTE is any network device that produces or consumes data. All CobraNet devices are DTEs.
Ethernet
A Local Area Network (LAN) protocol that transmits information between computers at speeds of 10 Mbps (megabits per second). It is one of the most widely implemented LAN standards.
Fast Ethernet
A newer version of Ethernet, also known as 100BASE-T. It supports data transfer rates of 100Mbps. CobraNet operates on a Fast Ethernet network.
Full Duplex
Data can be transmitted and received simultaneously.
Gigabit Ethernet
Gigabit Ethernet is a newer version of Ethernet, also known as 1000BASE-T. It supports data transfer rates of 1000 Mbps (1 gigabit).
Half Duplex
Data can only be transmitted in one direction at a time (i.e., a device cannot transmit and receive data simultaneously).
Hub
Hub is not a technically concise term. The term can be used to refer to either a Repeater Hub or a switched Switching Hub.
Link Aggregation
A means for making multiple Ethernet links act as a single higher capacity, fault tolerant link. Link aggregation is also known as trunking.
Mbps
Short for megabits per second, it is a measure of data transfer speed.
Media Converter
A Media Converter is typically a two port device that accepts one type of media on one port and a different media on the other. Common Ethernet media types are twisted pair, multimode and single mode fiber. Some hubs and switches include media conversion via plug in module options for various media types.
Meshing
A fusion of spanning tree protocol and link aggregation. Eliminates loops while creating higher capacity, fault tolerant links among interconnected (meshed) switches. Meshing is only available on HP ProCurve switches.
Multicast Addressing
Data which is Multicast is addressed to a group of, or all DTEs on a network. All DTEs receive multicast addressed data and decide individually whether the data is relevant to them. A Switched Hub is typically not able to determine appropriate destination port or ports for multicast data and thus must send the data out all ports simultaneously just as a Repeater Hub does. Multicast addressing is to be avoided whenever possible since it uses bandwidth network wide and since all DTEs are burdened with having to decide whether multicast data is relevant to them.
Multicast Bundle
A multicast bundle supports a one-to-many routing of audio on the network. Ethernet multicast addressing is used to deliver a multicast bundle. Because a multicast bundle consumes bandwidth network-wide, use of this delivery service must be rationed on a switched network.
Multimode Fiber
A fiber-optic cable commonly used in data communications and short haul telecommunications. A multimode fiber is built of two types of glass arranged in a concentric manner. Two sizes of fiber are available: 62.5/125um is used primarily in data communications, 50/100um is used primarily in telecommunications applications. The standard for transmission of 100Mbit Ethernet over 62.5/125um multimode fiber is called 100BASE-FX. Multimode fiber and its associated transceivers are fairly economical. 100BASE-FX has a 2 kilometer distance limitation.
Network Diameter
The longest cable distance between any two DTEs on the network.
Network Topology
The physical and logical relationship of nodes in a network; networks typically have a star, ring, tree or bus topology, or some combination.
NIC
A NIC or Network Interface Card is an expansion board inserted into a computer in order to connect the computer to a network. Typically, NICs are designed for a particular type of network and media, although some can serve multiple networks
Node
A processing location. A node can be a computer, a switch, a CobraNet device, or any other device that has a unique network address.
Repeater Hub
An Ethernet multi-port repeater. A data signal arriving in any port is electrically regenerated and reproduced out all other ports on the hub. A repeater hub does not buffer or interpret the data passing through it. An Ethernet network is typically wired in a star configuration and the hub is at the center. Hubs are available with port counts from 4 to 24. There are two grades of Fast Ethernet hubs: Class I and Class II. Class II hubs deliver higher performance than the Class I hubs. Most hubs shipping today are of the Class II variety. The use of hubs require that all devices on the network run in half duplex mode.
Ring
A network topology in which all nodes are connected in a closed loop.
Run Length
Each type of media has a limitation in the length of a point-to-point run between two devices. When maximum run length guidelines are exceeded it may not be possible to establish a valid network connection or data may be corrupted. Longer distances can be achieved by upgrading the media or using multiple runs in series.
Single Mode Fiber
A fiber optic cable built from a single type of glass. Data is carried over single mode fiber in the coherent light produced by a laser. While the single mode fiber cable cost approximately the same as a multimode cable, the cost of the optical transmitters and receivers is significantly more for a single mode installation than multimode. However, single mode fiber systems are able to achieve much greater transmission distance than multimode. There is no official standard for carrying Ethernet over single mode fiber. Proprietary single mode fiber systems each have their own run length limits; all exceed the 2 kilometer multimode limit. Some systems offer lengths in excess of 100 kilometers.
Spanning Tree Protocol
An IEEE standard protocol (802.1D) allowing detection and elimination of loops in Ethernet networks. Spanning tree protocol is implemented on most managed switches.
Star
A network topology in which all nodes are connected to a central network device such as a hub or switch.
Switch
See Switching Hub.
Switching Hub
A Switching Hub, or simply “Switch”, examines addressing fields on data arriving at each port and attempts to direct the data out the port or ports to which the data is addressed. Data may be buffered within the Switching Hub to avoid the collision condition experienced within a Repeater Hub. A network utilizing Switching Hubs realizes higher overall bandwidth capacity as data may be received through multiple ports simultaneously without conflict. Switches are full-duplex devices. A network utilizing switches to connect network segments is referred to as a switched network.
Trunking
See Link Aggregation.
Unicast Addressing
Data which is unicast is addressed to a specific DTE. A switching hub may examine the unicast address field of the data and determine on which port the addressed DTE resides and direct the data out only that port. Delivery of an e-mail message is an example of unicast data addressing.
Unicast Bundle
A unicast bundle supports a one-to-one routing of audio on the network. Ethernet unicast addressing is used to deliver a unicast bundle. Because unicast addressing is friendly to Ethernet switches, unicast bundles should be used for audio delivery whenever possible.
Unregulated Traffic
Refers to any data transmitted onto a network by non-CobraNet devices. Unregulated traffic is particularly offensive on a repeater network as it interferes with CobraNet’s collision avoidance mechanism and can result in audio dropouts. On a switched network, unregulated traffic is only a problem if it appears in such copious quantity as to overload the network.