190 Questions
Which transmission medium is commonly used for digital communication due to its high speed and low errors?
Glass (optical fiber)
What defines the frame format of digital transmissions at the Data Link Layer?
Frame format
In analog voice communication, which type of wire is commonly used to send electrical signals to a central office?
Copper wire
What does Hertz measure in the context of electrical energy cycles?
Frequency
How is the Bit Error Rate (BER) calculated in digital communications?
of errored bits / total number of bits sent
Why is a low Bit Error Rate (BER) essential for high-speed data transmission?
To improve the data integrity
What is the most common type of coaxial cable used for home audio, video, and TV transmission equipment?
RG-6
In fiber optic cables, what is the portion that light travels through?
Glass core
What is the purpose of the ouster sheath in a fiber optic cable?
To protect the fiber cable
Which type of cable supports large amounts of data and distances effectively?
Fiber optic cable
What type of equipment can operate in bidirectional mode supporting full-duplex communications in fiber optics?
Single-mode optical equipment
What allows for multiple wavelengths of light to travel through a single fiber strand in fiber optics?
Wavelength division multiplexing (WDM)
Which element impacts transmission when there is no clear line of sight between two endpoints or when there is moisture in the air?
Air
What is the primary function of a structure wiring system in networking?
Be flexible and customizable
Where does building backbone cabling terminate to provide connectivity to desktop locations in a networking setup?
Intermediate distribution frame (IDF) or wiring closet
In a structured wiring system, what is used to physically connect the workstation to the workstation outlet and the horizontal workation cabling patch panel to the switch?
Patch cables
What is the primary purpose of MAC addresses in an Ethernet frame's header?
To identify both the source and destination nodes uniquely
What distinguishes the frame layout between Ethernet II and IEEE 802.3 Ethernet standards?
The type field indicating Network Layer protocol
In the context of Ethernet frames, what does an error checking field typically do?
Detects errors in the transmitted data
How do IEEE 802.3 Ethernet standards differ from Ethernet II regarding Network Layer protocol identification?
Incorporating a Logical Link Control sublayer
What technical solution is recommended for improving network speed and connectivity within an organization?
Supporting high-speed LAN connections in the MAN and data center
What is a significant feature of early Ethernet LAN technology deployment?
Adoption of baseband bus topology
Which physical requirements influenced the deployment of early Ethernet LANs?
Integrity of the cabling
Why did early adopters of Ethernet technology shift from Thicknet to Thinnet coaxial cabling?
Thinnet was easier to implement
What was a significant advancement in cabling technology that influenced early Ethernet deployments?
'Structured cabling' systems promoting unshielded twisted-pair cabling
What was the major driving force behind the use of unshielded twisted-pair cabling for workstation connections?
The 10Base-T standard and specification
Which IEEE standard defined Ethernet running at 10 Mbps using Thicknet coaxial cable?
802.3
In what year was the IEEE standard 802.3ak introduced?
2004
What is the IEEE standard that supports 40 Gbps and 100 Gbps to support both endpoint and link aggregation over single-mode fiber?
802.3ba
Which IEEE standard provides for Power over Ethernet (PoE) using four pairs of unshielded twisted-pair cabling?
802.3at
What is the IEEE 802.3 standard for 1 Gbps using twisted-pair cable?
802.3ab
Which IEEE standard introduced Ethernet running at 100 Mbps, known as Fast Ethernet?
802.3u
What is the purpose of separating and internetworking LANs?
To enhance security, traffic segmentation, and network management
Which technology had to be used before IEEE 802.1Q VLAN for connecting file servers to departmental LANs?
Local connections
What is the main objective of internetworking using Layer 2 and Layer 3 networking?
Achieving high-speed backbone connectivity
What is a characteristic of a repeater in an Ethernet network?
Regenerates the Ethernet signal without any change
Why were LAN hubs popular in the late 1980s and early 1990s for home LANs?
To easily expand the number of workstations on the same LAN
What is a disadvantage of using LAN hubs in businesses and organizations?
Increased network security risks
What is a key consideration when designing LANs for real-time applications?
'Supporting time-sensitive protocols'
What is the main purpose of CSMA/CD in handling collisions?
To detect collisions and retransmit after a delay
How does collision detection work in CSMA/CD?
By retransmitting data after receiving notification of a collision
Why is Ethernet considered nondeterministic?
Because it listens and transmits without preventing all collisions
How does CSMA/CD provide scalability compared to other LAN technologies?
By evolving rapidly to support higher Ethernet speeds
What happens if an Ethernet frame is deemed invalid during transmission?
A collision is detected, and the transmitting node stops sending data
Why is the backoff algorithm used in CSMA/CD?
To delay retransmission attempts after a collision
What role do Layer 2 and Layer 3 LAN switches play in avoiding collisions?
They provide each device with its own dedicated LAN connection
In what way does structured wiring impact LAN connections?
It facilitates migration to faster Ethernet speeds on desktops
What happens when two frames collide during transmission?
The frames are detected as invalid, triggering a retransmission delay
Why does Ethernet use a nondeterministic transmission approach?
To listen and transmit without trying to prevent all collisions
What is the primary function of switches in a network?
Examining each frame and determining its destination based on MAC addresses
What distinguishes Layer 2 switches from hubs and repeaters in terms of traffic management?
Layer 2 switches isolate traffic from uninterested nodes
How do Layer 2 switches handle frames based on the destination MAC address?
Locate the address in its address table and forward it accordingly
What is the purpose of cut-through switching in network devices?
Forwarding frames based on the destination MAC address immediately
Which technology contributed to the simplification of Ethernet LAN technology implementations in the 1990s?
IEEE 802.3i (10Base-T) specification
What is one advantage of using unshielded twisted-pair cabling for Ethernet connections?
Simplified moves, additions, and changes of network connectivity
How did the introduction of Gigabit Ethernet impact network connections?
Enabled high-speed applications to drive to the desktop at Layer 2
What role does Quality of Service (QoS) routing play in modern networking infrastructures?
Prioritizing time-sensitive protocols like voice and video traffic over email and web surfing
What is a key benefit of utilizing VLANs in a network infrastructure?
Isolating traffic between nodes that frequently exchange packets
How do Layer 2 switches contribute to improving network performance?
Reducing traffic to uninterested nodes by creating collision domains
Which pin configuration is typically used for all RJ-45 connectors and patch panels in Ethernet LANs with UTP transmission media?
TIA-568B
What is the purpose of a crossover cable in networking?
To connect two devices directly without a switch
Which organization is the current owner of the TIA/EIA 568 standards family?
TIA
What sublayer of the Data Link Layer controls access to the media?
Media Access Control (MAC)
Which IEEE LAN standards define a 48-bit MAC address?
IEEE 802.3
What happens if two devices on an Ethernet LAN have the same MAC address?
There will be network errors and collisions
What does MAC spoofing refer to in networking?
Changing MAC addresses to cause network issues
What does the Logical Link Control (LLC) sublayer do in networking?
Controls linking logically
What is a critical factor to consider when designing Ethernet networks to ensure the lowest cost of connectivity?
Port density
When deciding between Layer 2 and Layer 3 edge switches in network design, what factor should be primarily considered?
Real-time applications and time-sensitive protocols needs
In Ethernet network design, what is the main purpose of using Power over Ethernet (PoE)?
Supporting IP phones for VoIP
Which aspect drives the requirements for Layer 2 and Layer 3 resiliency and redundancy in a network design?
Real-time applications and failover needs
When assessing switch architecture choices in Ethernet networks, what technology parameter should be considered?
Dual processors
What is a critical consideration for organizations needing access to server farms and real-time applications in their Ethernet networks?
100 Gbps Ethernet LAN trunks
What is the primary function of using PoE switches in edge networks?
To simplify electrical power distribution for IP phones at desktop locations
Why is it crucial to segment or isolate workgroup PCs and workstations within the same physical switch or VLAN?
To enhance the security controls by hard-coding MAC addresses
What differentiates an edge network from a traditional LAN in terms of physical connectivity?
Edge networks connect desktops physically closer to the wiring closet.
In the context of workgroup LANs, what is the significance of using Layer 2 or Layer 3 switches?
They enable VoIP and real-time protocol support at the desktop level.
What is the main purpose of configuring separate voice and data VLANs within a Layer 2 or Layer 3 switch?
To physically separate voice and data IP packets within Ethernet frames
Why is it essential to implement Layer 2 or Layer 3 resiliency between workgroup LAN switches and server connections?
To ensure network availability in case of switch failures
What is the primary purpose of implementing redundant power supplies or battery backup units in PoE LAN switches?
To ensure highly available phone service and dial tone
Why is it recommended to implement separate voice and data VLANs in PoE LAN switches?
To separate voice traffic from data traffic for better network management
What is the main advantage of using a centrally located wiring closet in a PoE workgroup LAN switch design?
To simplify structured wiring installations
What aspect of PoE LAN switch design focuses on preventing collisions between workgroup LANs?
Interconnecting workgroup LANs with switches
In a departmental LAN, what does it mean for each workgroup LAN to be a separate collision domain?
Each workgroup's traffic does not interfere with other workgroups' traffic
Why are Layer 2 switches essential in departmental LANs connecting multiple workgroup LANs?
To direct frames to the appropriate destinations between workgroups
What is a major advantage of collapsed backbone networks over other topologies?
Reduced number of devices required
In a collapsed backbone topology, what is a key drawback related to the central switch?
Single point of failure
What distinguishes the campus collapsed backbone from the building collapsed backbone?
Connection of multiple building backbones
What is a common characteristic of the Distribution network in network connection levels?
Connecting building backbone networks to department LANs
How does Metropolitan area network (MAN) connectivity differ from Metro Ethernet LAN connectivity?
Metro Ethernet supports wire-speed LAN connectivity within a region.
What advantage does using single-mode fiber optic cabling provide for carrier backbone networks?
Increased physical distance for Ethernet LAN connections
What is the primary reason fiber optic cabling is preferred for long-distance Ethernet connectivity?
It has no distance limitations like copper cabling.
How does Layer 2 switching differ from Layer 3 routing in terms of handling network traffic?
Layer 2 switching provides faster traffic direction than Layer 3 routing.
What is the key distinction between a multilayered hierarchical backbone and a flat backbone network topology?
Multilayered hierarchical backbones rely on physical device locations to isolate LANs.
Why are load-balancing, redundancy, and subsecond failover essential requirements for backbone network connectivity?
To minimize the impact of hardware failures and ensure high availability.
What is the primary role of VLANs and Ethernet tagging in interconnecting LANs beyond a single physical switch?
To allow VLANs to be uniquely identified and extend beyond multiple physical switches.
Why do workgroup LANs easily interconnect by connecting to a common backbone network?
Because Ethernet frames and IP usage are consistent among different LAN speeds.
What type of cabling is essential for achieving 25, 40, and 100 Gbps Ethernet backbone trunking?
Multimode fiber optics
Why is Layer 2 and Layer 3 resiliency vital for campus and building backbone networks?
To achieve sub-second failover
What is the key advantage of using high-end servers and databases with dual NIC cards at 25, 40, and 100 Gbps speeds?
Enhanced wire-speed connectivity
What is a critical requirement for campus backbone connections to ensure maximum bandwidth and throughput?
Fiber optics usage
How do high-speed backbone connections between departmental LANs and workgroup LANs benefit users?
Provides greater access to applications and data at higher speeds
Why are Layer 2 and Layer 3 resiliency crucial for campus and building backbone networks?
To achieve sub-second failover
What technology enables high-end servers and databases to offer wire-speed connectivity?
Dual NIC cards
Why is the use of fiber optics considered critical for maximizing bandwidth on backbone network connectivity?
To achieve higher speeds with reliability
How do 25, 40, or 100 Gbps trunks contribute to a resilient and high-speed backbone connection?
By aggregating 10 GigE backbone connections
What type of cabling should be used for building backbone connections in a structured wiring system according to the primer?
Multimode fiber cabling
How should wiring closets be positioned within the main building based on the primer's guidelines?
Vertically stacked through the main building
What is the maximum distance recommended by the primer for positioning wiring closets from a workstation outlet?
90 meters
In what situations should multimode fiber cabling be used according to the structured wiring system primer?
Building backbone cabling
What technology should power Voice over Internet Protocol (VoIP) phones according to the structured wiring system primer?
Power over Ethernet Plus (PoE+)
How many strands of fiber optic cabling should be used from the data center to each wiring closet in a structured wiring system based on the primer?
12 strands
What is the primary purpose of the plenum-rated sheathed UTP cables in a horizontal workstation cabling system?
To resist catching fire and melting plastic
In structured wiring systems, what is typically housed in the data center or equipment room?
Network equipment
What is the purpose of backbone cabling in a structured wiring system?
To support high-speed backbone connections
What is the defining characteristic of the building cabling entrance for outdoor cabling?
Use of metallic conduit path
Why is there no need for copper backbone cabling when VoIP is used?
VoIP eliminates analog phone lines
What is the significance of cross-connections between the Layer 3 PoE+ switch and the workstation cabling?
To ensure Layer 2 or Layer 3 resiliency
What is the primary function of battery backup, redundant network switches, and generator backup power in the data center?
To maintain network availability
Why are multimode and single-mode fiber cables preferred for backbone cabling?
Providing high-speed connections
What is the purpose of using SC connectors in a fiber optic patch panel?
Terminating fiber optic cabling
What is a key characteristic of a metallic conduit used as a building entrance for outdoor cabling?
Provides a pathway into the building
What is the main difference between LC and SC fiber connectors?
LC connectors are used for multimode fiber, while SC connectors are used for single-mode fiber.
What is the advantage of using APC or UPC connectors in SC connectors?
They reduce attenuation and back reflection in optical signals.
When might ST connectors be required over SC connectors?
For existing equipment compatibility.
What is the primary function of a fiber transceiver in a network setup?
Convert optical light signals to electrical signals.
In what situation would you need to use higher-powered fiber transceivers?
When longer distances are required for data transmission.
Which fiber optic cabling type is recommended when using 850 nm laser-optimized technology?
Multimode optical fiber cabling with 50/125 μm dimensions.
What is the distinguishing feature of ST connectors compared to LC and SC connectors?
ST connectors push in and turn to lock into place, unlike LC and SC connectors.
What determines the choice between single-mode and multimode fiber optic cabling?
The distance over which data transmission needs to occur in the network.
Why is it recommended to use 62.5/125 μm multimode optical fiber cabling for SC connectors?
It offers better compatibility with patch panels and transceivers.
What is the main purpose of a Smartjack in a network setup?
To provide various methods of connectivity between the service provider and internal network
How is impedance mismatch typically measured in structured cabling for certification purposes?
In decibels (dB)
In a structured cabling system, what is the primary purpose of labeling all physical cables properly?
To assist in identifying cable connections and terminations
Which organization is responsible for maintaining and managing the RCDD professional certification for engineers in low-voltage structured cabling systems?
BICSI
What is a key characteristic of TIA-568-C.2 standard in structured cabling systems?
Contains specifications for designing UTP cabling systems
What distinguishes Anixter from Black Box in terms of products supplied for structured cabling systems?
Anixter offers low-voltage electrical distribution while Black Box focuses on testers
What type of documentation format is recommended to provide as-built documentation for structured cabling systems?
.xls spreadsheets or database
What does TIA/EIA-568.3-D standard specify regarding structured cabling systems?
Performance and technical specifications for twisted-pair cabling systems
What type of cabling sheath is required for installation above the ceiling in areas with air conditioning flow?
Plenum-rated cabling sheaths
What organization's standards must structured wiring system installations comply with?
BICSI
What device is needed to measure distance, attenuation, and continuity for each fiber strand in a fiber optic cabling system?
Optical Time Domain Reflectometer (OTDR)
Which test measures the amount of signal loss on a cable and is also known as insertion loss?
Attenuation test
What should the impedance of the cable match to prevent signal reflections?
Impedance of any elements connected to the cable
Which of the following tests verifies that the proper wire is terminated in the correct pin number on an 8-pin, RJ-45 connector?
Pin configuration test
What measurement test is directly proportional to the nominal velocity of propagation (NVP)?
Propagation delay test
"Insertion loss" is commonly referred to as:
$4^2 - 12$ loss test
What type of fiber cabling should be used for building backbone connections in the structured wiring system according to the primer?
Single-mode fiber
How far should wiring closets be positioned from a workstation outlet based on the primer's guidelines?
No more than 90 meters
What type of switch should be used to power phones in a Voice over Internet Protocol (VoIP) setup as per the primer?
Power over Ethernet Plus (PoE+) Layer 3 switch
How many strands of fiber cabling should be provided to each wiring closet from the data center in the structured wiring system layout described?
12 strands
What link speed is mentioned to require only one backbone connection if switches are stackable within the wiring closet?
40 GigE
What is the recommendation for the campus environment and long-haul interbuilding connections with regards to fiber cabling in the structured wiring system design?
Use single-mode fiber cabling
What type of cabling sheath is required for installation above the ceiling in an area with air conditioning flow?
Plenum-rated cabling sheaths
Which testing is NOT required for UTP cable pairs in a structured wiring system?
Impedance testing
What technology is needed to measure distance, attenuation, and continuity for each fiber strand in a structured cabling system?
Optical time domain reflectometer (OTDR)
What technology parameter should be considered when performing a certification test on unshielded, twisted-pair transmission media?
Propagation delay
Which test measures the actual distance of the cable to ensure it meets telecommunication wiring standards?
Length test
In structured cabling systems, what does an Optical Time Domain Reflectometer (OTDR) measure for fiber optic cabling?
Distance, attenuation, and continuity
What is the role of a Smartjack in a network setup?
Network interface connection
Why is impedance matching essential for cable elements connected to the cable in a structured wiring system?
To maximize signal strength
What does an OTDR measure for each fiber strand in a structured cabling system?
Distance, attenuation, and continuity
Which parameter is directly proportional to Propagation Delay in unshielded twisted-pair media?
Nominal Velocity of Propagation (NVP)
What type of cables are needed in a horizontal workstation cabling system if the drop ceiling acts as the air conditioning return duct?
Plenum-rated sheathed UTP cables
What is the primary function of backbone cabling in a structured wiring system?
Support long-term growth and high-speed backbone connections
What is the purpose of calculating the maximum physical distance from the wiring closet to the workstation outlet?
Ensure compliance with distance limitations for the cabling used
What is the significance of using multimode and single-mode fiber cables from the data center to each wiring closet?
Provide long-term growth and high-speed backbone connections
Why should plenum-rated sheathed UTP cables be used in a horizontal workstation cabling system instead of PVC-sheathed UTP cables?
PVC cables are not fire-retardant and pose a fire hazard
What is terminated when making a physical connection between actual copper wire and a wiring block in a structured wiring system?
Voice copper cables onto RJ-45 patch panels
What fundamental function does a data center or equipment room serve in a structured wiring system?
Houses computer equipment, network equipment, and backbone cabling
What is the primary purpose of having a metallic conduit path as a building entrance for outdoor cabling?
Provides a physical path into the building for cabling
What is housed in the equipment room located centrally within a building's structured wiring system?
Computer equipment, network equipment, and backbone cabling system
What is the purpose of a smartjack in a network setup?
To facilitate connectivity between the service provider's demarcation point and an internal network
What organization is dedicated to the education and certification of engineers in low-voltage structured cabling systems?
BICSI
Which standard contains requirements for designing and installing structured cabling systems for consumers, businesses, and commercial buildings?
TIA/EIA-568
What is the benefit of properly labeling all physical cables when they are terminated onto a patch panel?
To facilitate future maintenance and troubleshooting
What is the purpose of the Registered Communications Distribution Designer (RCDD) professional certification managed by BICSI?
To verify proficiency in low-voltage structured cabling systems
Why is it important for all cabling documentation to be provided in a spreadsheet or database format?
To allow review and acceptance with official test results
In structured cabling systems, where are all physical cables terminated to facilitate connectivity within a networking setup?
At the wiring closet RJ-45 patch panel
What is the function of the TIA-568.3-D standard?
To specify twisted-pair cabling system performance and technical specifications
What is an important aspect of cable labeling in structured cabling systems?
To ensure proper cable maintenance and troubleshooting
Which device is installed between the service provider’s demarcation point and an internal network?
Smartjack
Which type of fiber optic cabling is recommended for single-mode fiber applications?
8-10 μM/125 uM with ST connectors
For new construction projects, which connector is mentioned as the default choice?
SC connector
Which connector type is used for single-mode fiber and long-distance, high-speed transmissions?
LC connector
What is the primary purpose of utilizing fiber transceivers in a network?
To convert optical light signals into electrical signals
In fiber optics, what does a bidirectional transceiver support?
Two-way communications
Which type of transceiver is specifically used for 10 GigE fiber connections?
SFP+ transceiver
What is the main function of Gigabit interface converters (GBIC) in network setups?
To convert between optical and electrical signals
Which hot-swappable optical transceiver supports link aggregation up to 40 GigE standards?
QSFP+ transceiver
Study Notes
Physical Layer
- Transmission mediums: air (radio frequency), metal (copper unshielded twisted-pair, shielded twisted-pair, or coaxial cable), or glass (optical fiber)
- Digital transmission requires high speed and low errors
- Physical layer supports transmission of 1's and 0's
Transmission Media
- Coaxial cable:
- Anatomy: outer insulation, braided sheath, dielectric, conductor
- Common types: RG-6 (home audio/video/TV), RG-58 (RF transmission), RG-59/U (closed-circuit TV), RG-8U (10Base5 Ethernet), RG-60U (HDTV/high-speed cable modems)
- Fiber optic cable:
- Anatomy: glass core, cladding, primary buffer, outer sheath
- Supports large amounts of data and distances
- Can operate in bidirectional mode (full-duplex) using single fiber and wavelength division multiplexing (WDM)
Structure Wiring System
- Modular cabling solution that is flexible and customizable
- Comprises workstation outlet, RJ-45 connections, wire closet/intermediate distribution frame (IDF), main distribution frame (MDF) or data center, campus or building backbone distribution
- Supports high-speed bandwidth and connectivity to desktops
Data Link Layer
- Precedes the Physical Layer and prepares data for transmission
- Comprises two sublayers: Media Access Control (MAC) and Logical Link Control (LLC)
- MAC: controls access to the media, listens to the network, and transmits or receives Ethernet frames
- LLC: controls linking logically, organizes upper layer protocols, and allows multipoint communications
Ethernet and IEEE 802.3 Frame Formats
- Ethernet frame: pair of addresses, data, and error checking field
- Differences between Ethernet II and IEEE 802.3 frame formats:
- Ethernet II: 2-byte type field indicating Network Layer protocol
- IEEE 802.3: IEEE 802.2 Logical Link Control (LLC) sublayer indicating service access points and Network Layer protocols
Solving Business Challenges
- Connecting PCs, workstations, and servers using Ethernet switches and unshielded twisted-pair cabling
- Sharing and accessing applications using LAN servers with enterprise-wide access controls
- Sharing files and printers using standardized access controls and permission rights
- Communicating through multiple methods (VoIP, email, IM chat, conferencing, and collaboration)
- Supporting high-speed network access to desktops and data center backbone connections### CSMA/CD Concept
- CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is a concept that prevents data collisions on a network by ensuring only one device transmits data at a time.
- It uses Carrier Sense, Multiple Access, and Collision Detection to handle collisions.
Carrier Sense
- NIC cards listen on the physical media for specific voltage levels or carrier signals.
- If the coast is clear, the NIC can transmit on the network.
- If someone is already transmitting, the carrier sense voltage level is different.
Multiple Access
- NIC cards can transmit simultaneously, causing a collision situation on the physical media.
- This collision is noticed by the NIC card transceivers that listen to specific voltage levels or carrier signals.
Collision Detection
- NIC cards react to signal collisions by retransmitting after receiving notification that a collision occurred.
- Although this solution solves the problem caused by the initial collision, bus topologies with excessive collisions can also cause problems.
Ethernet
- Ethernet uses a nondeterministic, unpredictable transmission approach.
- It doesn't try to prevent all collisions; it merely listens and transmits.
- The potential for collisions is what makes Ethernet nondeterministic.
- Because all nodes on an Ethernet network share the same transmission media, there must be some way to handle collisions.
Evolution of Ethernet
- CSMA/CD and the deployment of Ethernet LAN technologies evolved rapidly from 10 Mbps baseband coaxial LAN topologies to GigE and metro-Ethernet MAN connectivity.
- Ethernet has become the de facto standard for transporting IP-based communications to the desktop.
Advantages of Ethernet
- CSMA/CD has proven to be more scalable than other LAN technologies.
- Ethernet technology and chipsets were able to increase Ethernet bandwidth speeds 10 times from 10 Mbps to 100 Mbps to 1000 Mbps to 10 Gbps speeds.
Structured Wiring Systems
- Structured wiring systems provide high-grade unshielded twisted-pair cabling to the desktop.
- Users can now migrate their LAN connections from 10Base-T to 100Base-T to 1000Base-T or 10 Gigabit Ethernet to the desktop.
LAN Switches
- LAN switches make it possible for many devices to be LAN-attached via Ethernet.
- Internetworking LANs using inexpensive hardware, Ethernet can be physically extended using different transmission media and transceivers.
Security, Traffic Segmentation, and Ease of Network Management
- Security, traffic segmentation, and ease of network management are all reasons to separate and internetwork LANs.
- Prior to the use of IEEE 802.1Q VLAN technology, file servers had to be locally connected to departmental LANs.
Server Access and High-Speed Backbone
- Server access and maximizing performance, high-speed backbone are key considerations when designing LANs.
- Where you put servers can impact how you design the network.
Physically Extending the Cabling Distances
- Physically extending the cabling distances or conversion to other transmission media can be done at the Physical Layer.
- Because Ethernet LANs were based on Thicknet and Thinnet coaxial cabling, it was necessary to overcome distance limitations to support growth in the LAN.
Repeaters and Media Converters
- Repeaters are used when converting from one cabling type to another, usually to extend the physical distance of the Ethernet bus topology.
- A repeater has two ports and regenerates the Ethernet signal subject to signal attenuation.
Ethernet Cable Types
- 10Base5 (Thick Ethernet): RG-58 coaxial, 500 meters
- 10Base2 (Thin Ethernet): RG-58 coaxial, 185 meters
- 10Base-T (Twisted-Pair Unshielded twisted-pair): 100 meters
- 100Base-TX (Fast Ethernet): UTP (Cat 5 and higher), 100 meters
- 1000Base-T (Gigabit Ethernet): UTP (Cat 5e and higher), 100 meters
- 10GBase-T (10 Gigabit Ethernet): UTP (Cat 6/6a or higher), 100 meters
- 25GBase-T/40GBase-T: UTP (Cat 8, with 2 connectors), 30 meters
LAN Hubs
- LAN hubs provided a cheap and easy way to expand the number of ports onto the same shared logical bus topology.
- Hubs were popular in the late 1980s and early 1990s.
- Hubs echo every frame they receive out of every other port, including the receiving port.
Bridges and Switches
- Bridges and switches examine each frame as it enters a port and determine its destination based on MAC addresses learned.
- Switches examine each frame that enters, filter or forward based on the destination MAC address.
- Layer 2 and Layer 3 networking can achieve efficient networks by segmenting a network into multiple collision domains.
Network Design Fundamentals
- Early Ethernet networks were designed utilizing bus topologies.
- The original IEEE Ethernet standard, IEEE 802.3, defined a network running at 10 Mbps using Thicknet coaxial cable.
Ethernet Network Design
- Advances in 100Base-T and 1000Base-T (Gigabit Ethernet) utilizing unshielded twisted-pair cabling have changed the landscape of how best to provide high-speed network connections to the desktop.
- Real-time applications require time-sensitive protocols.
- Getting packets to their destinations requires traffic prioritization and quality of service (QoS) routing.
Metropolitan Area Networks (MANs) and Wide Area Backbone Networks
- Metropolitan area networks (MANs) are aggregations of remote buildings, but within a regional MAN service area.
- Wide area backbone networks are cloud-based wide area network infrastructures such as Multiprotocol Label Switching (MPLS) for wide area IP network connectivity.
Edge Network Design Criteria
-
Port density
-
Power over Ethernet (PoE)
-
Layer 2 versus Layer 3 edge switch
-
Layer 2 and Layer 3 resiliency and redundancy
-
Layer 2 and Layer 3 trunking
-
Switch architecture
-
Switch security### PoE LAN Switches
-
PoE LAN switches can deliver electrical power to IP phones using data-grade 4-pair, unshielded twisted-pair cabling.
-
A minimum Category 5e or Category 6 UTP cabling should be installed to support long-term, high-speed data and communications connectivity.
-
PoE LAN switches support IP cameras and wireless access points used in wireless LANs.
IEEE 802.3 PoE Standards
- There are two different IEEE 802.3 PoE standards: IEEE 802.3af–2003 and IEEE 802.3at–2009.
- IEEE 802.3af–2003 draws up to 15.4 watts of power from the PoE switch port to power an IP phone.
- IEEE 802.3at–2009 draws up to 25.5 watts of power from the PoE switch port to power an IP phone, IP cameras, and wireless access points.
PoE Workgroup LAN Switch Best Practices
- Use structured wiring from a centrally located wiring closet for 10/100/1000Base-T installations.
- Ensure Category 5, 5e, 6, 6a, 7, or 8 UTP cabling is used to maximize physical distances up to 100 meters or 330 feet.
- Commingle voice and data on the same physical 4-pair UTP cable from the workstation outlet to the wiring closet patch panel.
- Install PoE LAN switches with redundant power supplies or battery backup units to ensure highly available phone service and dial tone.
- Enable separate voice and data VLANs to separate voice traffic from data traffic once it hits the Layer 2 or Layer 3 PoE LAN switch.
Edge Network: Departmental LAN
- A departmental LAN connects multiple workgroup LANs and keeps them separate.
- Switches provide this feature.
- In most cases, Layer 2 switching efficiently directs frames to the appropriate destinations within the same workgroup and moves Ethernet frames between workgroups.
Departmental LAN Design Considerations
- Total number of workgroup LANs: Switches come in all sizes and port densities.
- Physical distance between workgroup LANs: Distance is Ethernet’s enemy—errors increase over greater distances.
- Copper cabling has fixed distance limitations.
- Fiber optic cabling can support longer distances for Ethernet connectivity.
- Layer 2 switching: Layer 2 switching is based on MAC address filtering/forwarding.
- VLANs and Ethernet tagging: Layer 2 VLANs can be uniquely identified and extend beyond more than one physical switch using IEEE 802.1Q Ethernet tagging.
- Internetworking solution: Creating small, workgroup LANs that do not share the same broadcast domain optimizes performance.
- Internetworking at Layer 2 or Layer 3 can interconnect LANs and VLANs together.
Switched LAN Aggregation
- Edge switches require a high-speed backbone trunk connection.
- Load-balancing, redundancy, and subsecond failover are all requirements for backbone network connectivity.
- Workgroup file servers housed in data centers require high-speed backbone connectivity.
- Network security: Implementing proper layered security controls starts with locking down switch ports at the MAC layer, enabling Secure Shell (SSH) protocol for remote access, and implementing internal firewalls and access control lists to filter traffic.
Backbone Network
- A backbone network allows workgroup LANs to interconnect with connecting servers.
- A backbone network is typically of higher speed than the workgroup LAN, generally utilizes fiber optic cabling, and is redundant or highly available, given the switch architecture.
- There are two common approaches to implementing a backbone network: Multilayered hierarchical backbone and flat backbone.
Campus Backbone: Collapsed Data Center
- The collapsed backbone topology provides scalability beyond individual buildings.
- A collection of central switches that connect multiple building collapsed backbones can create an organizational campus network while retaining the separation of each workgroup, department, and building.
Ethernet Backbone
- Metropolitan area networks are supported by carrier backbone networks capable of supporting Ethernet LAN connections.
- Metro Ethernet LAN connectivity provides customers located within a single county or region wire-speed LAN connectivity.
- Metro Ethernet is cost-effective, reliable, and scalable, and provides superior bandwidth just like a local LAN connection.
25, 40, and 100 GigE: Server Farms and Backbone Trunking
- Organizations utilize both multimode and single-mode fiber optic cabling.
- With single-mode fiber optics, 25, 40, and 100 Gbps Ethernet backbone trunking is now possible.
- Aggregating 10 GigE backbone connections and interconnecting Ethernet LAN switches with 25, 40, or 100 Gbps trunks provides both a resilient and high-speed backbone connection.
Structured Wiring System Primer
- The scope of this structured wiring system primer is specific to a single building location.
- The building has 4 floors with approximately 100 users per floor.
- FIGURE C-1 depicts the sample building layout and cabling distribution viewpoint.
Design Approach
- Building entrance cabling must be extended to the data center or equipment room if possible; otherwise, use multimode fiber cabling from the data center to each floor’s wiring closet to act as the building backbone cabling.
- Use single-mode fiber cabling for campus environments and long-haul interbuilding connections.
- Building backbone cabling should be multimode fiber, with 12 strands to each wiring closet from the data center.
Components of a Structured Wiring System
- A structured wiring system has six foundational building blocks: building cabling entrance, data center or equipment room, backbone cabling, telecom room/wiring closets, horizontal cabling, and workstation/office location.
- This primer reviews each building block and provides guidelines for what you need to assess, design, and implement them.
Explore the concepts of bridging and routing in Internetworking LANs, including extending Ethernet using different media and transceivers, segmenting departmental traffic, and separating LANs for security and network management purposes.
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