Glossary

CWDM: (Coarse Wavelength Division Multiplexing)
A method of transmitting several connections parallel over one fiber optic line.
Transmission works over different wavelengths (colors) on the same fiber, which do not influence each other.
As opposed to DWDMDWDM
(Dense Wavelength Division Multiplexing)
A method of transmitting many connections parallel over one fiber optic line.
Transmission works over different wavelengths (colors) on the same fiber, which
More ..., a relatively wide channel spacing is used, which leads to a more cost-saving technology, because temperature stabilized components are not needed. CWDM has been specified for use on distances up to 50 km.
The CWDM wavelength plan of the ITU-T Recommendation G.694.2 defines 18 wavelengths with a grid of 20 nm. But two of these are located in the area of the [Water Peak] and therefore are being omitted.
Because of this, CWDM provides 16 usable parallel data channels.

DWDM: (Dense Wavelength Division Multiplexing)
A method of transmitting many connections parallel over one fiber optic line.
Transmission works over different wavelengths (colors) on the same fiber, which are very close together on DWDM. Because of this, highly precise and temperature stabilized laser transmitters must be used. On the other hand, when using DWDM a distance of several 100 km can be covered.
By now, DWDM is available with up to 128 colors.

Freespace Optic: Optical data transmission "over the air". There are a variety of standards and data rates, depending on the wavelength in use.
Applications include connection of adjacent buildings and cross-linking of locations over a distances up to several km.
Permanent eye contact between both locations is always required.

GHMoIP: (Generic Hybrid Multiplexing over IP)
A protocol for the bundled transmission of several different serial/synchronous data streams over IP.
The GHMoIP protocol is routable and faciliates transmission through large IP networks and over wide distances.
Besides the data, it transports timing information for the clock recovery of each particular data stream.

OADM: (Optical Add-and-Drop Multiplexing)
Method of branching off wavelengths from and/or inserting them into CWDMCWDM
(Coarse Wavelength Division Multiplexing)
A method of transmitting several connections parallel over one fiber optic line.
Transmission works over different wavelengths (colors) on the same fiber
More ... or DWDMDWDM
(Dense Wavelength Division Multiplexing)
A method of transmitting many connections parallel over one fiber optic line.
Transmission works over different wavelengths (colors) on the same fiber, which
More ... lines.
Included are Drop/Pass components diverting one or more colors out of the multiplexed wavelengths and let the rest of them pass, which enables bus-type infrastructure cabling.
In addition, there are Drop-and-Insert components which extract single colors, and feed them in again. These are used for building e.g. redundant fiber optical backbone rings.

SFP: (Small Formfactor Plugable)
A standard for optical transceiver modules.
The SFP standard allows a flexible choice of fiber optic transceivers for devices with a SFP slot. Depending on the application, an individually selected SFP module containing the required technology and wavelength can be inserted. This way, the component can be fitted e.g. to any color of a CWDMCWDM
(Coarse Wavelength Division Multiplexing)
A method of transmitting several connections parallel over one fiber optic line.
Transmission works over different wavelengths (colors) on the same fiber
More ... backbone.

TDM: (Time Division Multiplexing)
A method of multiplexing and sending several data streams over one line, with the help of time.
Using this method, the data streams are being splitted into time slices, which will be transmitted on a rotating basis.
As opposed to the WDMWDM
(Wavelength Division Multiplexing)
A method of transmitting more than one data stream simultaneously over a fiber. This is being achieved by using a different wavelength for each one. The simplest
More ... methods, TDM is applicable on copper as well as on fiber lines. Only on the latter, there is also the possibility of nesting and combining TDM and WDMWDM
(Wavelength Division Multiplexing)
A method of transmitting more than one data stream simultaneously over a fiber. This is being achieved by using a different wavelength for each one. The simplest
More ....

Trunking: Bundling of several lines in parallel to form one common connection.
Benefits of this are the higher achievable data rate (as a sum of all data rates of the respective lines) and the better robustness: if one line fails, the throughput will decrease by the data rate of the failed line, but the connection as a whole will still remain stable.

Water Peak: The wavelength area on a standard fiber that will be most affected by attenuation caused by hydroxyl ions that are present within the structure of the glass core.
With CWDMCWDM
(Coarse Wavelength Division Multiplexing)
A method of transmitting several connections parallel over one fiber optic line.
Transmission works over different wavelengths (colors) on the same fiber
More ... there are two wavelengths of the 20 nm grid that reside in this area, and their commercial use is being avoided because of this problem.

WDM: (Wavelength Division Multiplexing)
A method of transmitting more than one data stream simultaneously over a fiber. This is being achieved by using a different wavelength for each one. The simplest case is multiplexing two data streams by using two wavelengths at 1310 and 1550nm.
More channels will be transmitted using CWDMCWDM
(Coarse Wavelength Division Multiplexing)
A method of transmitting several connections parallel over one fiber optic line.
Transmission works over different wavelengths (colors) on the same fiber
More ... or DWDMDWDM
(Dense Wavelength Division Multiplexing)
A method of transmitting many connections parallel over one fiber optic line.
Transmission works over different wavelengths (colors) on the same fiber, which
More ....