Ethernet Networking and Data Encapsulation - PL Flashcards
This is a contention-based media access method that allows all hosts on a network to share the same link’s bandwidth.
Ethernet
Ethernet uses both of these layers’ specifications, presented with information relative to both layers, and need to effectively implement, troubleshoot, and maintain an Ethernet network.
Data Link and Physical Layer
refers to a network scenario wherein one device sends a frame out on a physical network segment forcing every other device on the same segment to pay attention to it.
Collision Domain
What happens when two devices on a single physical segment transmit simultaneously?
When two devices on a single physical segment transmit simultaneously, a collision occurs, requiring the devices to retransmit their data.
refers to a group of devices on a specific network segment that hear all the broadcasts sent out on that specific network segment
Broadcast Domain
This is usually a boundary delimited by physical media like switches and routers.
Broadcast Domain
This refer to a logical division of a network segment, where all host can communicate via a Data Link layer, hardware address broadcast
Broadcast Domain
This refers to a group of devices on a specific network segment that hear all the broadcasts sent out on that specific network segment
Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
This was actually created to overcome the problem of the collisions that occur when packets are transmitted from different nodes at the same time.
Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
What occurs when there is a collision on an Ethernet LAN?
- A jam signal informs all devices that a collision occurred.
- The collision invokes a random back-off algorithm
- Each device on the Ethernet segment stops transmitting for a short time until its back-off timer expires
- All host have equal priority to transmit after the timers have expired.
This is defined in the original IEEE 802.3 Ethernet specification, Cisco says Ethernet uses only one wire pair with a digital signal running in both directions on the wire.
Half-duplex Ethernet
This uses the CSMA/CD protocol I just discussed to help prevent collisions and to permit retransmitting if one occurs.
Half-Duplex
If a hub is attached to a switch, why must it operate in half-duplex mode?
A hub must operate in half-duplex mode because the end stations need to detect collisions, as hubs do not separate collision domains like switches do.
What are the six situation you can full-duplex ethernet
- With a connection from a switch to a host
- With a connection from a switch to a switch
- With a connection from a host to a host
- With a connection from a switch to a router to a router
- With a connection from a switch to router
- With a connection from a router to a host
This decides on the exchange capability, which means it checks to see if it can run at 10, 100, or even 1000 Mbps. It then checks to see if it can run full-duplex, and if it can’t, it will run half-duplex.
Auto-detect Mechanism
- There are no collisions in full-duplex mode.
- A dedicated switch port is required for each full-duplex node.
- The host network card and the switch port must be capable of operating in full-duplex mode.
- The default behavior of 10Base-T and 100Base-T hosts is 10 Mbps half-duplex if the autodetect mechanism fails, so it is always good practice to set the speed and duplex of each port on a switch if you can
This is responsible for Ethernet addressing, commonly referred to as MAC or hardware addressing.
Ethernet at the Data Link Layer
This is responsible for framing packets received from the
Network layer and preparing them for transmission on the local network through the Ethernet contention-based media access method.
Ethernet at the Data Link Layer
It uses the Media Access Control (MAC) address burned into each and every Ethernet network interface card (NIC).
Ethernet Addressing
What is a MAC (hardware) address, and how is it formatted?
A MAC (Media Access Control) address is a 48-bit (6-byte) address used to uniquely identify network devices. It is written in hexadecimal format (e.g., 00:1A:2B:3C:4D:5E).
This is assigned by the IEEE to an organization. It’s composed of 24 bits, or 3 bytes, and it in turn assigns a globally administered address also made up of 24 bits, or 3 bytes, that’s supposedly unique to each and every adapter an organization manufactures.
Organizationally Unique Identifier
What is the function of the high-order bit in a MAC address, and what does a value of 0 indicate?
it indicates that the address is a unicast MAC address assigned to a specific device and may appear in the source portion of the MAC header.
What does it mean when the high-order bit in a MAC address is set to 1?
It indicates that the address is either a broadcast or multicast address in Ethernet, meaning it is intended for multiple devices rather than a single recipient.
What is the function of the Global/Local (G/L or U/L) bit in a MAC address?
The Global/Local (G/L or U/L) bit in a MAC address determines whether the address is universally or locally administered.
What does it mean when the Global/Local (G/L or U/L) bit in a MAC address is set to 0?
When the Global/Local (G/L or U/L) bit in a MAC address is set to 0, it means the address is globally administered and assigned by the IEEE, ensuring it is unique across all network devices.
What does it mean when the Global/Local (G/L or U/L) bit in a MAC address is set to 1?
When the Global/Local (G/L or U/L) bit in a MAC address is set to 1, it means the address is locally administered by the device or network administrator, rather than being assigned by the IEEE.
What do the low-order 24 bits of an Ethernet address represent?
The low-order 24 bits of an Ethernet address represent a manufacturer-assigned or locally administered code, which uniquely identifies a device within a network.
This the use to limit either 1 or 0
Binary Digits or bits
This a group either 4 or 8 bits together
Nible and Byte
These are placed in a value spot, starting at the right and moving left, with each spot having double the value of the previous spot
Binary Numbers
What is the typical decimal format?
Base-10 Number
Hex is short for?
Hexadecimal
This is a numbering system that uses the first six letters of the alphabet
Hexadecimal
This is responsible for combining bits into bytes and bytes into frames
Data Link Layer
How does the MAC frame format provide error detection?
MAC frame Format
What is the process of encapsulating a frame within a different type of frame called?
Tunneling
This is an Ethernet frame consists of an alternating 1,0 pattern that provides a 5 MHz clock signal at the start of each packet, which allows the receiving devices to lock the incoming bit stream.
Preamble
The preamble is seven octets and the SFD is one
octet (synch).
Start Frame Delimiter (SFD)/Synch
This transmits a 48-bit value using the least significant bit (LSB) first.
Destination Address
This is used by receiving stations to determine whether an incoming packet is addressed to a particular node.
Destination Address
This can be an individual address or a broadcast or multicast MAC address.
Destination Address
This is a 48-bit MAC address used to identify the transmitting device, and it uses the least significant bit first.
Source Address
This uses a Length field, but the Ethernet frame uses a Type field to identify the Network layer protocol.
Length or Type 802.3
This is a field at the end of the frame that’s used to store the cyclic redundancy check (CRC) answer
Frame Check Sequence (FCS)
This is a mathematical algorithm that’s run when each frame is built based on the data in the frame.
Cyclic Redundancy Check
they created and implemented the first Ethernet LAN specification, which the IEEE used to create the IEEE 802.3 committee.
Digital, Intel, and Xerox
What was the original speed and media used for Ethernet at the Physical Layer?
The original Ethernet at the Physical Layer operated at 10 Mbps and initially ran on coaxial cable. It later evolved to use twisted-pair and fiber optic physical media.
This is the standards body that creates
the Physical layer specifications for Ethernet.
Electronic Industries Alliance and the newer
Telecommunications Industry Association (EIA/TIA)
This specifies that Ethernet use a registered jack (RJ) connector on unshielded twisted-pair (UTP) cabling (RJ45).
Electronic Industries Alliance and the newer
Telecommunications Industry Association (EIA/TIA)
This is a 10 Mbps Ethernet standard that uses Category 3 UTP (Unshielded Twisted Pair) wiring for cable runs up to 100 meters. It uses an RJ45 connector (8-pin modular connector) and features a physical star topology while operating as a logical bus network.
10Base-T (IEEE 802.3) Ethernet
This is also known as Fast Ethernet, operates at 100 Mbps and uses EIA/TIA Category 5, 5e, or 6 UTP with two-pair wiring. It supports one user per segment, with a maximum cable length of 100 meters. It utilizes an RJ45 connector, follows a physical star topology, and functions as a logical bus network.
100Base-TX (IEEE 802.3u) Ethernet
This is a 100 Mbps Fast Ethernet standard that uses 62.5/125-micron multimode fiber optic cabling. It follows a point-to-point topology and supports cable runs up to 412 meters.
100Base-FX (IEEE 802.3u) Ethernet
It uses ST (Straight Tip) and SC (Subscriber Connector) connectors, which serve as media interface connectors.
100Base-FX (IEEE 802.3u) Ethernet
This is a 1 Gbps (Gigabit Ethernet) standard that uses copper twisted-pair cable, specifically twinax (balanced coaxial pair).
1000Base-CX (IEEE 802.3z) Ethernet
It has a maximum cable length of 25 meters and uses a 9-pin High-Speed Serial Data Connector (HSSDC). This standard is commonly used in Cisco’s Data Center technologies.
1000Base-CX (IEEE 802.3z) Ethernet
This is a Category 5, four-pair UTP wiring up to 100 meters long and up to 1 Gbps.
1000Base-T (IEEE 802.3ab)
This is a 1 Gbps Gigabit Ethernet standard that uses multimode fiber-optic cable (MMF) instead of copper twisted-pair. It operates with a short-wavelength (850 nm) laser.
1000Base-SX (IEEE 802.3z) Ethernet
This standard is commonly used for short-distance fiber-optic connections.
1000Base-SX (IEEE 802.3z) Ethernet
This is a Single-mode fiber that uses a 9-micron core and 1300 nm laser and can go from 3 kilometers up to 10 kilometers.
1000Base-LX (IEEE 802.3z)
The implementation of 1 Gigabit Ethernet running over multimode fiber-optic cable instead of copper twisted-pair cable, using short wavelength laser.
1000Base-SX (IEEE 802.3z)
This is a Single-mode fiber that uses a 9-micron core and 1300 nm laser and can go from 3 kilometers up to 10 kilometers
1000Base-LX (IEEE 802.3z)
This is a Cisco specified standard for Gigabit Ethernet communication. 1000BaseZX operates on ordinary single-mode fiber-optic links with spans up to 43.5 miles (70 km).
1000Base-ZX (Cisco standard)
This is a standard proposed by the IEEE 802.3ancommittee to provide 10 Gbps connections over conventional UTP cables, (category 5e, 6, or 7 cables).
10GBase-T (802.3.an)
This allows the conventional RJ45 used for Ethernet LANs and can support signal transmission at the full 100-meter distance specified for LAN wiring.
10GBase-T
Three types of Cables
- Straight-through Cable
- Crossover Cable
- Rolled Cable
This can support speeds up to 1 Gbps (Gigabit Ethernet) with a maximum distance of 100 meters. It is commonly used for 100 Mbps networks but is rated for gigabit speeds.
Category 5 Enhanced UTP cable
This is designed for 1 Gbps but can also support 10 Gbps at shorter distances, typically up to 55 meters.
Category 6 UTP cable
The straight-through cable is used to connect the following devices:
- Host to switch or hub
- Router to switch or hub
How many wires are used in a straight-through Ethernet cable, and what is its purpose?
A straight-through Ethernet cable uses four wires to connect Ethernet devices. It is commonly used to connect different types of devices, such as a computer to a switch or router. The wiring follows the T568A or T568B standard on both ends.
The crossover cable can be used to connect the following devices:
- Switch to switch
- Hub to hub
- Host to host
- Hub to switch
- Router direct to host
- Router to router
How many wire pairs are used in Gigabit Ethernet over UTP compared to 10Base-T and 100Base-T?
This only two wire pairs are used for data transmission. However, for Gigabit Ethernet (1000Base-T), all four wire pairs are required to achieve 1 Gbps speeds over UTP cabling.
This isn’t used to connect any Ethernet connections together, you can use a rolled Ethernet cable to connect a host EIATIA 232 interface to a router console serial communication (COM)port.
Rolled Cable
What type of cable is used to connect a PC, Mac, or iPad to a Cisco router or switch?
Rolled Cable
These are Eight wires are used in this cable to connect serial devices, although not all eight are used to send information, just as in Ethernet networking.
These are probably the easiest cables to make because you just cut the end off on one side of a straight-through cable, turn it over, and put it back on—with a new connector.
Rolled Cable
What software can be used to establish a console connection to a Cisco router or switch?
Once the correct console cable is connected from a PC to a Cisco router or switch, you can use an emulation program such as PuTTY or SecureCRT to establish a console connection and configure the device.
This allows for very fast transmission of data, is made of glass(or even plastic!), is very thin, and works as a waveguide to transmit light between two ends of the fiber
Fiber Optics
This has been used to go very long distances, as in intercontinental connections, but it is becoming more and more popular in Ethernet LAN networks due to the fast speeds available and because, unlike UTP, it’s immune to interference like cross-talk.
Fiber Optics
The cladding is a fiber standard that allows manufacturers to make connectors for all fiber cables. The last piece of this cable is the buffer, which is there to protect the delicate glass.
125 Microns Fiber Optic Cable
What are the two major types of fiber optics
- Single Mode
- Multimode
This is more expensive, has a tighter cladding, and can go much farther distances than multimode. The difference comes in the tightness of the cladding, which makes a smaller core, meaning that only one mode of light will propagate down the fiber.
Single-Mode
This is looser and has a larger core so it allows multiple light particles to travel down the glass.
Multimode
This is when a host transmits data across a network to another device, the data goes through a process and wrapped with protocol information at each layer of the OSI model.
Encapsulation
This is use to communicate and exchange
information in each layer.
Protocol data units (PDUs)
They contain control information that is attached to the data at each layer. This information is usually found in the header at the beginning of the data field but can also appear in the trailer at the end of the data. PDUs help ensure proper data transmission between network devices.
Protocol data units (PDUs)
This is a piece of data created and attached data field in transport layer.
Segment
This is used to get each segment to the correct network.
Logical Addressing
These adds a control header to the segment handed down from the Transport layer
Packet or Datagram
The Data Encapsulation Method Works Like This
- User information is converted to data for transmission on the network.
- Data is converted to segments, and a reliable connection is set up between the transmitting and receiving hosts.
- Segments are converted to packets or datagrams, and a logical address is placed in
the header so each packet can be routed through an internetwork. - Packets or datagrams are converted to frames for transmission on the local network. Hardware (Ethernet) addresses are used to uniquely identify hosts on a local network segment.
- Frames are converted to bits, and a digital encoding and clocking scheme is used.
This helps us understand where things belong, how things fit together, and what functions go where.
Hierarchy
This helps summarize a complex collection of details into an understandable model, bringing order from the chaos.
Hierarchy
This can help you design, implement, and maintain a scalable, reliable, cost-effective hierarchical internetwork
Cisco Hierarchical Model
This is literally the core of the network
Core Layer
is responsible for transporting large amounts of traffic both reliably and quickly.
Core Layer
is to switch traffic as fast as possible.
Core Layer
Don’t Do in Core Layer
- Never do anything to slow down traffic
- Don’t support workgroup access here
- Avoid expanding the core
Want to achieve as we design the core:
- Design the core for high reliability
- Design with Speed in mind
- Select routing protocols with lower convergence times
This is sometimes referred to as the workgroup layer and is the communication point between the access layer and the core.
Distribution Layer
to provide routing, filtering, and WAN access and to determine how packets can access the core, if needed.
Distribution Layer
This must determine the fastest way that network service requests are handled—for example, how a file request is forwarded to a server
Distribution Layer
Handled at the distribution layer:
- Routing
- Implementing tools (such as access lists), packet filtering, and queuing
- Implementing security and network policies, including address translation and firewalls
- Redistributing between routing protocols, including static routing
- Routing between VLANs and other workgroup support functions
- Defining broadcast and multicast domains
This controls user and workgroup access to internetwork resources.
Access Layer
This is sometimes referred to as the desktop layer.
Access Layer
This talks about the network resources most users need will be available locally because the distribution layer handles any traffic for remote services.
Access Layer
Functions to be included at the access layer:
- Continued (from distribution layer) use of access control and policies
- Creation of separate collision domains (micro segmentation/switches)
- Workgroup connectivity into the distribution layer
- Device connectivity
- Resiliency and security services
- Advanced technology capabilities (voice/video, etc.)
