Chapter 15: Telecommunications Systems Flashcards
Cable
- An assembly of one or more insulated conductors or optical fibers within an enveloping sheath.
- An assembly of one or more cable units of the same type and
category in an overall sheath. It may include an overall screen. - The act of installing cable.
Cable Tray
A support mechanism used to route and support telecom can other cables. Cable trays may be equipped with side walls or barriers to constrain a cable’s horizontal placement or movement.
Connectivity
Patch panels, cabling, connectors, and cable management are used to create and maintain electrical and optical circuits.
Cross-connect
A facility enabling the termination of cabling elements and their interconnection or cross-connection.
Demarcation Point
A point where the operational control or ownership changes, typically between the service provider and the customer.
Pathway
A facility for the placement of telecom cable.
Splice
A joining of conductors, which is meant to be permanent.
What is the purpose of the entrance room?
The entrance room is the location where the conversion between the outside plant and the inside plant cable takes place. The entrance room is also where the access provider demarcation is usually provisioned.
What is the purpose of the MDA?
The MDA is the telecommunications space that provides a central point of distribution using the main cross-connect/MD (MC/MD).
Name the four parts of equipment typically located in the MDA.
- Core routers
- Core, spine, or interconnection layer LAN and SAN switches
- High-performance computing switches
- PBX or voice gateways T-3 (M13) multiplexors
What is the purpose of the IDA?
The IDA is the space that supports the immediate cross-connect. It may be used to provide a second-level cabling subsystem in data centers too large to be accommodated with only MDAs and HDAs.
What is the purpose of HDA?
The HDA is used to serve equipment not supported by a horizontal cross-connect (HC) or zone distributor (ZD) in an IDA or MDA. The HAD is the distribution point for cabling to the EDAs.
Identify three pieces of equipment typically housed in the HDA.
- LAN switches
- SAN switches
+ Keyboard/video/mouse (KVM) switches.
What is the purpose of the ZDA?
The ZDA is an optional interconnection point within the horizontal cabling located between the HDA and the EDA to allow frequent reconfiguration and added flexibility.
What is the purpose of the EDA?
The EDA is space allocated for end equipment, including all forms of telecom equipment, (e.g., computer, & telephony equipment). EDA areas shall not serve the purposes of an entrance room, MDA, IDA, or HDA.
What is the typical depth of duct banks and conduits?
600 mm (24”) to 750 mm (30”) below surface grade.
What is the required depth of telecom cabling in a solid-bottomed cabling pathway?
150 mm (6”)
What is the minimum required access headroom provided from, the top of the overhead pathway to the obstruction located above such as another pathway of the ceiling?
200 mm (8”)
What is the minimum recommended access headroom from the top of the overhead pathway to the obstruction located above such as another pathway or the ceiling?
300 mm (12”)
For underfloor cable trays, what shall be the minimum clearance between the top of the cable tray and the bottom access floor?
50 mm (2”)
What is the minimum clearance between layers of underfloor cable trays that run parallel and are stacked directly above each other?
200 mm (8”)
What is the function of the backbone cabling?
To provide connections between the MDA, IDA, HDA, and entrance rooms in the data center cabling system.
What is horizontal cabling?
The portion of the telecom cabling system that extends from the EO in the EDA to the TIA HC or ISO/CENELEC ZD in an HDA, IDA, or MDA.
What is the minimum performance level of balanced twisted pair that is acceptable for backbone cabling?
Category 3/ Class C
What is the minimum performance level of balanced twisted-pair that is required for horizontal cabling?
Cat 6/Class E (TIA/CENELEC); Cat 6A/ Class EA (ISO)
Why might the recommended bend radius for a cable during installation be greater than the recommended bend radius after the cable is installed?
To minimize tension and deformation as the cables pass around the corners during the installation.
What is meant by “abandoned cable”?
Installed telecom cabling that is not terminated at both ends at a connector or other equipment and not identified for future use with some form of labeling.
What is the required action for an abandoned cable?
It must be removed as required by the AHJ.
__________ of optical fiber connector end-faces is one of the major causes of network malfunctions.
Contaimination
What is the smallest sized contaiminant that may cause network disruption?
Less than 2 micrometers.
What is the maximum height recommended for a rack or a cabinet?
2.4 m (8’)
What percent of mesh doors should be open to airflow for allowing chilled air entrance or evacuating heated exhaust air from the cabinet?
minimum of 63% open to airflow for allowing chilled air entrance or evacuating heated exhaust air from the cabinet.
List three design criteria for the cable tray systems.
- Cabling should be managed to maintain their min. bend radius requirements.
- Cable trays cannot be used as walkways or ladders or support for people unless specifically designed for such purposes.
- Support for cable ladders or cable trays should be independent of non-telecom utilities.
What is the function of the “Meet Me Room”?
It provides a way for communication firms to exchange data with other telecom carriers and ISPs housed in the same facility.
Why is cleaning optical fiber connectors very important?
Contamination of optical fiber connector end-faces is one of the major causes of network malfunctions.
This provides connection between the MDA, IDA, HDA, and entrance rooms in the data center cabling system.
Backbone cabling
This is the portion of the telecom cabling system that extends from the EO in the EDA to the TIA HC or ISO/CENELEC ZD in an HDA, IDA, or MDA.
Horizontal cabling
