Networking Fundamentals Flashcards
1
Q
Interconnection of Network made possible by…
A
Open Systems Interconnection (OSI)
2
Q
OSI Model
7 layers
A
- Application
- Presentation
- Session
- Transport
- Network
- Data link
- Physical
3
Q
OSI: TCP/IP Model
A
- Application:
- Application
- Presentation
- Session - Host-to-Host
- Transport - Internet
- Network - Network Access
- Data link
- Physical
4
Q
Network Protocol is a …
A
Standard set of rules that determines how systems will communicate across networks.
5
Q
Open Network Architecture is…
A
One that no vendor owns, that is not proprietary, and that can easily integrate various technologies and vendor implementation of those technologies.
6
Q
OSI:Encapsulation
A
Each protocol at a specific OSI layer on one computer communicates with a corresponding protocol operating at the same OSI layer on another computer.
7
Q
OSI: Protocol Data Unit (PDU)
A
A protocol at each layer adds its own information to the message, creating a PDU.
8
Q
OSI: Protocol at each layer has 3 responsibilities..
A
- Communication to above layer
- Communication to lower layer
- Communication to same layer in the other network
9
Q
OSI: Attacks, network can be used as
A
- used as a channel for attack
- the target of an attack
10
Q
OSI: Examples of Application Layer Protocol
A
- SMTP: Simple Mail Transfer Protocol
- HTTP:Hypertext Transfer Protocol
- LDP:Line Printer Daemon
11
Q
OSI: Presentation layer is
A
- Concerned not with the meaning but with the syntax and format of the data
- Compresses data / Encrypt
12
Q
OSI: Session Layer
A
Responsible for establishing a connection between two applications, maintaining it during the transfer of data, and controlling the release of this connection.
13
Q
OSI:Session Layer works in 3 phases:
(Dialog Management)
A
- Connection establishment
- Data Transfer
- Connection release
14
Q
OSI: Examples of Session Protocol layer
A
- L2TP: layer 2 tunnelling protocol
- PPTP: Point-to-Point Tunnelling Protocol (PPTP)
- RPC: Remote Procedure Call
15
Q
OSI: Session layer Protocol can enable communication between two applications to happen in 3 different modes: (technical term)
A
- Simplex
- Half-Duplex
- Full-Duplex
16
Q
OSI: Session Layer Vs. Transport Layer
A
- Session Layer: Application-to-Application
- Transport Layer: Computer-to-Computer
17
Q
OSI: Which Layer Protocol is least used protocols in a network environment;
A
Session Layer Protocols
18
Q
OSI: Transport Layer
A
When two computers are going to communicate through a connection-oriented protocol, they first agree on how much information each computer will send at a time , how many o verify the integrity of the data once received, and how to determine whether a packet was lost along the way. The 2 computers agree on these parameters through a handshaking process at the transport layer
19
Q
OSI:Network Layer, layer 3
A
The main responsibilities of the network layer are to insert information into the packet’s header so it can be properly addressed and routed, and then to actually route the packet to its proper destination.
20
Q
OSI: Data Link Layer, Layer 2
A
The network layer has already figured out how to route the packet through the various network devices to its final destination, but we still need to get the data over to the next, directly connected device. This happens at the data link layer.
21
Q
OSI: Data Link Layer, Layer 2 has two functional sub layers:
A
- Logical Link Control (LLC): which interface with network layer above
- Media Access Layer (MAC): designed to interface with the physical layer below.
22
Q
OSI: Data Link Layer, Layer 2 - Framing
A
When the data link layer applies the last header and trailer to the data message, this is referred to as framing m. This unit of data is now called a frame
23
Q
ISO: Physical Layer, layer 1
A
Converts bits into electromagnetic signals for transmission.
24
Q
PROTOCOL: Layer 7 - Application
A
- File Transfer Protocol (FTP)
- Network Time Protocol (NTP)
- Simple Mail Transfer Protocol (SMTP)
- Internet Message Access Protocol (IMAP)
- Hyper Transfer Protocol (HTTP)
25
PROTOCOL: Layer 6 - Presentation
-American Standard Code for Information Interchange (ASCII)
- Tagged Image File Format (TIFF)
- Motion Picture Experts Group (MPEG)
- Musical Instrument Digital Interface (MIDI)
26
PROTOCOL: Layer 5 - Session
- Layer 2 Tunnelling Protocol (L2TP)
- Network Basic Input Output System (NetBIOS)
- Password Authentication Protocol (PAP)
- Point-to-Point Tunnelling Protocol (PPTP)
- Remote Procedure Call (RPC)
27
PROTOCOL: Layer 4 - Transport
- Transmission Control Protocol (TCP)
- User Datagram Protocol (UDP)
- Stream Control Transmission Protocol (SCTP)
- QUIC (not an acronym)
28
PROTOCOL: Layer 3 - Network
- Internet Protocol (IP)
- Internet Control Message Protocol (ICMP)
- Internet Group Management Protocol (IGMP)
- Routing Information Protocol (RIP)
- Open Shortest Path First (OSPF)
29
PROTOCOL: Layer 2 - Data Link
- Address Resolution Protocol (ARP)
- Reverse Address Resolution Protocol (RARP)
- Serial Line Internet Protocol (SLIP)
- Wireless Ethernet (IEEE 802.11)
30
PROTOCOL: Layer 1 - Physical
- RS/EIA/TIA-422, RS/EIA/TIA-423, RS/EIA/TIA-449, RS/EIA/TIA-485
- 10Base-T, 10Base2, 10Base5, 100Base- TX, 10Base-FX, 10Base-T, 1000Base-T, 1000Base-SX
- Integrated Services Digital Network (ISDN)
- Digital Subscriber Line (DSL)
- Synchronous Optical Networking (SONET)
31
Bus Topology are of two main types:
- Linear bus topology
- Tree bus topology
32
Bus Topology is prevalent in
Vehicular networks, of which are Controller Area Network (CAN) bus is by far the most popular standard
33
Example of full mesh topology
A Typical Internet of Things (IoT) home automation network work using ZigBee.
34
Medium Access Control (MAC) mechanisms deal with…
(Resides data link Layer 2)
How computer systems communicate over these media and are built into the network interfaces
35
3 most common approaches to MAC
- Carrier Sense Multiple Access
- Token Ring
- Polling
36
MAC: Carrier Sense Multiple Access (CSMA)
(Collisions)
Which provides a standard way to access the shared medium, communicate, and recover from any errors that may occur.
37
MAC: Carrier Sense Multiple Access (CSMA) - 2 Variants
- Collision Detection (CD)
- Collision Avoidance (CA)
38
MAC:CSMA: Collision Detection (CD)
Protocol, they monitor the transmission activity, or carrier activity, on the wire so they can determine when would be the best time to transmit data.
39
MAC:CSMA: Collision Avoidance(CA)
In which all stations with data to transmit first check the medium to see if it’s quiet, If it is, they send their data. If it isn’t, they start a random time before they check again
40
MAC:CSMA: Token Passing
(No collisions)
Some MAC technologies also use tokens, which are 24-bit control frames used to control which computers communicate at what intervals.
41
MAC:CSMA:
Collision and Broadcast Domains.
A Collision Domain is…
- a group of devices that are contending, or competing, for the same shared communication medium.
- Example: All devices that are connected to a particular wireless access point (WAP) belong to the same collision domain.
- Collision domains are sets of computing nodes that may produce collisions when they transmit data.
- These are normally nodes connected by hubs, repeaters, or wireless access points.
42
Increase in Network Latency means…
Data Transmission Delays
43
CSMA:MAC
Broadcast Domain
Are sets of computing nodes that all receive a layer 2 broadcast frame. These are normally all nodes that are interconnected, with no routers in between them.
44
CSMA:MAC: Polling
- Polling is a medium access control mechanism that relies on a primary station that periodically polls all others in its collision domain.
- Each polled device responds by stating whether or not it has anything to send. How urgent it is.
- Polling is much more common in WAN
45
Layer 2 Protocols
Examples
- Ethernet
- Token Ring
- FDDI
46
LAYER 2: PROTOCOL:
Ethernet
- Ethernet is a set of technologies that enables several devices to communicate on the same network.
- Ethernet usually uses a bus or star topology
47
LAYER 2: PROTOCOL:
Ethernet is defined by the following characteristics:
- Contention-based technology ( all resources use the same shared communication medium)
- Uses broadcast and collision domains
- Uses the CSMA access method
- Supports full-duplex communication
- Can use coaxial, twisted-pair, or fibre-optic cabling types, but most commonly uses UTP cables
- is defined by IEEE 802.3 family of standards
48
LAYER 2: PROTOCOL: Token Ring Technology
- Was originally developed by IBM and then defined by the IEEE 802.5.
- It uses Token passing technology with a star-configured topology
- The ring part of the name pertains to how the signal travel, which is in a logical ring.
- Each computer is connected to a central hub, called a Multi station Access Unit (MAU)
49
LAYER 2: PROTOCOL: Ethernet is also referred as…
Chatty Protocol
50
LAYER 2: PROTOCOL: Ethernet Ring employs a couple of mechanisms to deal with problems
- Active Monitor: mechanism removes frames that are continuously circulating on the network.
- Beaconing mechanism: if a computer detects a problem with the network, it sends beacon frame. This frame generates a failure domain, which is between the computer that issued the beacon and its neighbour downstream. The computers and devices within this failure domain will attempt to reconfigure certain settings to try to work around the detected fault
51
LAYER 2: PROTOCOL: Fiber Distributed Data Interface (FDDI). Employed for distances up to 100 Km. Often used in MAN
- Technology, developed by the American National Standards Institute (ANSI), is a high-speed, token-passing, medium access technology.
- Data Transmission speed up to 100 Mbps and is usually used as a backbone network using fibre-optic cabling.
- also provides fault tolerance by offering a second counter-rotating fiber ring.
52
LAYER2:PROTOCOL: Fiber Distributed Data Interface (FDDI) - Devices that connect to…
- Single-attachment station (SAS)
- Dual-attachment station (DAS)
- Single-attached concentrator (SAC)
- Dual-attached concentrator (DAC)
53
Transmission 3 Methods
(____Cast)
- Unicast: If a packet needs to go from the source computer to one particular system, unicast method is used.
- Multicast: if a packet needs to go to a specific group of systems, the sending system uses the multicast method.
- Broadcast: If a system wants all computers on its subnet to receive a message, it uses the broadcast method
54
Multicast Protocols
- a class D address (224.0.0.0 to 239.255.255.255)
- IPv43 Multicast protocols can be used to send out information multimedia data; and even real-time video, music, and voice clips
- Internet Group Management Protocol (IGMP) is used to report multicast group memberships to routers. e.g.: On-line streaming video and gaming activities
55
Layer 2 of the OSI model notes - As frames pass from one network device to another device,
- It has become necessary to secure network traffic at the frame level, which is layer 2 of the OSI model.
- 802.1AE is the IEEE MAC Security (MACSec) standard, which defines a security infrastructure to provide data confidentiality, data integrity, and data origin authentication.
- VPN connection provides protection at the higher networking layers, MACSecs provides hop-by-hop protection at layer 2.
56
INTERNET PROTOCOL NETWORKING: TCP/IP
- Transmission Control - Protocol/ Internet Protocol (TCP/IP) is a suite of protocols governs the way data travels from one device to another.
- IP is a network layer protocol and provides datagram routing services.
- It is a connectionless protocol that envelops data passed to it from the transport layer.
- IP’s main task is to support Internetwork addressing and packet routing,
57
INTERNET PROTOCOL NETWORKING: Main Protocol work at the Transport Layer
- TCP
- UDP
58
INTERNET PROTOCOL NETWORKING: Difference between TCP and UDP
- TCP: Connection Oriented Protocol: has the ability to identify this issue and resend the lost or corrupted packet.
- UDP: Best Effort and Connectionless protocol: it has neither packet sequencing nor flow and congestion control, and the destination does not acknowledge every packet it receives.
59
INTERNET PROTOCOL NETWORKING: The combination of protocol (TCP or UDP), Port, and IP address make up a…
Socket
60
INTERNET PROTOCOL NETWORKING: Port numbers up to 1023 (0 to 1023) are called…
Well-known ports
61
INTERNET PROTOCOL NETWORKING: Commonly used Protocols and the ports
- Secure Shell (SSH) port 22
- SMTP Port 25
- DNS port 53
- HTTP port 80
- NTP port 123
- IMAP port 143
- HTTP Secure (HTTPS) port 443
62
INTERNET PROTOCOL NETWORKING: 1024 to 49151
Registered Ports by Internet Assigned Numbers Authority (IANA)
63
INTERNET PROTOCOL NETWORKING: 49152 to 65535. Available to be used by any application on an “as needed” basis.
- Dynamic Ports (ephemeral ports)
64
INTERNET PROTOCOL NETWORKING: TCP must set up a virtual connection between two hosts before any data is sent. This means…
- The two host agree on certain parameters, data flow, windowing, error detection, and options.
- These issues are negotiated during the handshaking phase
65
INTERNET PROTOCOL NETWORKING: TCP 3 Way Handshaking
1. SYN
2. SYN/ACK
3. ACK
66
INTERNET PROTOCOL NETWORKING: If an attacker can correctly predict the TCP Sequence numbers that two systems will use, then he can create packets containing those numbers and fool the receiving system. He can take over the TCP connections between the 2 systems, which is referred to as…
TCP session hijacking
67
INTERNET PROTOCOL NETWORKING: message transferred via TCP and UDP
- TCP - Segment
- UDP - Datagram
68
INTERNET PROTOCOL NETWORKING: Data Structure: Data move through differ layers…
- Application: Data
- Transport: Segments
- Network: Packets
- Data link: Frames
69
INTERNET PROTOCOL NETWORKING: IP addressing: IPv4
- used by 70%
- 32 bits
- IPv6 uses 128 bits
70
INTERNET PROTOCOL NETWORKING: IP Addressing: Subnetting
Subnetting allows larger IP address ranges to be divided into smaller, logical, and more tangible network segments.
71
INTERNET PROTOCOL NETWORKING: IPv6 also called
IP next generation (IPng)
72
INTERNET PROTOCOL NETWORKING:Address Resolution Protocol: Each computer and network device require a unique IP address and a unique physical hardware address. The physical address also referred as…
Media Access Control (MAC) Address
73
INTERNET PROTOCOL NETWORKING:Address Resolution Protocol: what are addresses Network layer and Data link layer works with…
Network Layer: works with and understands IP Addresses
Data link layer: works with and understands physical MAC addresses.
74
INTERNET PROTOCOL NETWORKING:Address Resolution Protocol(ARP): What is the function of Address Resolution Protocol
MAC and IP addresses must be properly mapped so they can be correctly resolved. This happens through Address Resolution Protocol
75
INTERNET PROTOCOL NETWORKING:Address Resolution Protocol (ARP): Sometimes attackers alter a system’s ARP table so it contains incorrect information. This is called…
- ARP table cache poisoning
- Attackers goal is to receive packets intended for another computer
76
INTERNET PROTOCOL NETWORKING:Dynamic Host Configuration Protocol (DHCP)
- DHCP is a UDP-based protocol that allows servers to assign IP addresses to network clients in real time.
- DHCP server automatically checks for available IP addresses and correspondingly assign and IP address to the client.
77
INTERNET PROTOCOL NETWORKING:Dynamic Hosting Configuration Protocol (DHCP): DORA process
- Discover
- Offer
- Request
- Acknowledgment
78
INTERNET PROTOCOL NETWORKING:Dynamic Host Configuration Protocol (DHCP): Reverse Address Resolution Protocol (RARP):
As with ARP, RARP frames go to all systems on the subnet, but the RARP server responds.
79
INTERNET PROTOCOL NETWORKING:Dynamic Host Configuration Protocol (DHCP): Reverse Address Resolution Protocol (RARP): what was the reason for creating Bootstrap Protocol(BOOTP)?
Bootstrap Protocol created after RARP to enhance the functionality that RARP provides for disk less workstations
80
INTERNET PROTOCOL NETWORKING: Internet Control Message Protocol (ICMP) is
- Basically IP’s messenger boy. ICMP delivers status messages, report errors, replies to certain requests, and report routing information and it is used to test connectivity and troubleshoot problems on IP networks
- The most commonly understood use of ICMP is its use by the ping utility.
81
INTERNET PROTOCOL NETWORKING: Attack Using (ICMP)
Internet Control Message Protocol (ICMP) was developed to send status messages, not to hold or transmit user data. But someone figured out how to insert some data inside of an ICMP packet, which can be used to communicate to an already compromised system. This technique is called ICMP tunnelling, and is an older, but still effective, client/server approach that can be used by hackers to setup and maintain covert communication channels to compromised systems.
82
INTERNET PROTOCOL NETWORKING: Simple Network Management Protocol (SNMP)
- Simple Network Management Protocol was released in 1988 to help with the growing demand of managing network IP devices.
- 2 Components: managers and agents.
83
INTERNET PROTOCOL NETWORKING: Domain Name Service (DNS)
DNS is a method of resolving hostnames to IP addresses so names can be used instead of IP addresses within networked environments
84
INTERNET PROTOCOL NETWORKING: Network Address Translation (NAT)
- IP addresses have become scare (until the full adoption of IPv6) and expensive. So some smart people came up with Network Address Translation (NAT) which enables a network that does not follow the Internet’s addressing scheme to communicate over the internet.
- Most NAT implementation are stateful, meaning they keep track of a communication between the internal and an external host until that session is ended.
85
INTERNET PROTOCOL NETWORKING: Network Address Translation: 3 basic types of NAT implementations can be used:
- Static Mapping: Static IP
- Dynamic mapping: First-come, first-served basis
- Port address translation (PAT): IP address combined with ports
86
INTERNET PROTOCOL NETWORKING: Routing Protocol
Routing Protocols are used by routers to identify a path between the source and destination systems.
87
INTERNET PROTOCOL NETWORKING: Routing Protocol: Dynamic vs. Static
- Routing Protocol can be dynamic or static
- Dynamic Routing Protocol: can discover routes and build a routing table
- Static Routing Protocol: requires the administrator to manually configure the course router’s routing table
88
INTERNET PROTOCOL NETWORKING: Routing Protocol: Distance-Vector vs. Link-State
- Distance-Vector routing protocol make their routing decisions based on the distance or number of hops. The Protocol takes these variables and uses them with an algorithm to determine the best route for a packet.
- Link-state routing protocol: build more accurate routing table because they build topology database of the network. These protocols looks at more variables than just number of hops
89
INTERNET PROTOCOL NETWORKING: Routing Protocol: Interior Routing Protocols aka Internet Gateway Protocol
Route traffic with the same Anonymous Systems (AS)
- Routing Information Protocol (RIP): considered a distance vector protocol. Legacy Protocol. Slow performance and lack of functionality
- Open Shortest Path First (OSPF) - uses link state algorithm. More memory and CPU devices
- Interior Gateway Routing Protocol: distance-vector routing protocol
- Enhanced IGRP: distance-vector protocol
- Virtual Router Redundancy Protocol (VRRP): used in networks that require high availability
- Intermediate System to Intermediate System (IS-IS): link state protocol, allows each router to independently build a database or network’s topology
90
INTERNET PROTOCOL NETWORKING: Routing Protocol: Exterior Routing Protocol
- This is used by routers connecting different ASs are generically referred to as Exterior Gateway Protocol (EGPs)
- the Border Gateway Protocol (BGP) enables routers on different ASs to share routing information to ensure effective and efficient routing between the different AS networks.
- BGP uses combination of Distance-Vector and link-state functionality
91
INTERNET PROTOCOL NETWORKING: Routing Protocol attacks
A majority of the attacks have a goal of misdirecting traffic through the use of spoofed ICMP messages.
92
INTRANETS AND EXTRANETS: Intranet
When an organization uses web-based technologies that are only available inside its networks, it is using an intranet, a “private” network.
93
INTRANETS AND EXTRANETS: Extranet
An extranet extends outside the bounds of the organization’s network to enable two or more organizations to share common information and resources
94
METROPOLITAN AREA NETWORKS (MAN):
- Metropolitan are network is usually the a backbone that connects LANs to each other and LANs to WANs, the internet, and telecommunications and cable networks.
95
METROPOLITAN AREA NETWORKS (MAN): Synchronous Optical Networks (SONETs) or FEDDI rings and Metro Ethernet:
- A majority of today’s MANs are Synchronous Optical Networks (SONETs) or FEDDI rings and Metro Ethernet provided by the telecommunications service providers.
- The SONET and FEDDI rings cover a large area and businesses can connect to the rings via T1, fractional T1, and T3 lines
96
METROPOLITAN AREA NETWORKS (MAN): SONET
Synchronous Optical Network is a standard for telecommunications transmission over fibre-optic cables.
97
METROPOLITAN AREA NETWORKS (MAN): SONET is self healing- what does it mean?
If a break in the line occurs, it can use a backup redundant ring to ensure transmission continues.
98
METROPOLITAN AREA NETWORKS (MAN): Metro Ethernet:
Ethernet LANs can connect to the previously mentioned MAN technologies, or they can be extended to cover metropolitan area, which is called Metro Ethernet.
99
METROPOLITAN AREA NETWORKS (MAN): Multiprotocol Label Switching (MPLS)
These are more expensive but highly reliable and scalable, and used by large service providers
100
METROPOLITAN AREA NETWORKS (MAN): Architectures are commonly built upon 3 layers:
- Access
- Aggression / Distribution
- Core
101
METROPOLITAN AREA NETWORKS (MAN): WAN
Wide Area Network (WAN) technologies are used when communication needs to travel over a large geographical area.
102
METROPOLITAN AREA NETWORKS (MAN): WAN: Dedicated Links
- A dedicated link is also called a leased line or point-to-point link.
- It is one single link that is pre-established for the purposes of WAN communications between two destinations
- other technologies: X.25, frame relay, and ATM technologies
103
METROPOLITAN AREA NETWORKS (MAN): WAN: T-Carriers
- T-Carriers are dedicated lines that can carry voice and data information over trunk lines.
- They were developed by AT&T and were initially implemented in the early 1960s to support pulse-code modulation ( PCM) voice transmission.
104
METROPOLITAN AREA NETWORKS (MAN): WAN: most commonly used T-Carriers:
- T1 lines and T3 lines
- Both are digital circuits that multiplex several individual channels into a higher-speed channel.
105
METROPOLITAN AREA NETWORKS (MAN): WAN: T-Carriers: Time-Division multiplexing (TDM)
It means that each channel gets to use the path only during a specific time slot,
106
METROPOLITAN AREA NETWORKS (MAN): WAN: T-Carriers: T- Carriers: fractional T lines
Sometimes, T1 channels are split up between organizations that do not need the full bandwidth of 1.544mbps. These are called fractional T Lines
107
METROPOLITAN AREA NETWORKS (MAN): WAN: E -Carriers
E-carriers are similar to T-carrier telecommunication connections, where a single physical wire pair can be used to carry many simultaneous voice conversations by time-division multiplexing.
108
METROPOLITAN AREA NETWORKS (MAN): WAN: T-Carriers and E-Carriers
- While the T-Carriers and E-Carrier technologies are similar, they are not interoperable.
- E-Carriers used by European countries.
109
METROPOLITAN AREA NETWORKS (MAN): WAN: Optical Carrier
High-speed fiber-optic connections are measured in optical carrier (OC) transmission rates.
110
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: CSU/DSU:
- Channel Service Unit/ Data Service Unit (CSU/DSU) is required when digital equipment will be used to connect a LAN to a WAN.
- A CSU/DSU is necessary because the signals and frames can vary between the LAN equipment and the WAN equipment used by service providers.
111
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Switching
Circuit Switching: sets up a virtual connection that acts like a dedicated link between two systems. ISDN and telephone calls are examples of circuit switching.
- Packet Switching: packets from one connection can pass through a number of different individual devices, instead of all of them following one another through the same devices.
112
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Switching: Circuit Switching:
- Connection-oriented virtual links
- Traffic travels in a predictable and constant manner
- Fixed Delays
- Usually carries voice-oriented data
113
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Switching: Packet Switching:
- Packets can use many different dynamic paths to get to the same destination
- Traffic is usually bursty in nature
- Variable delays
- Usually carries data-oriented data
114
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Frame Relay
Frame relay is a WAN technology that operates at the data link layer. It is a WAN solution that uses packet-switching technology to let multiple organizations and networks share the same WAN medium, devices, and bandwidth.
115
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Virtual Circuits
- Frame relay (and X.25) forwards frames across virtual circuits.
- These circuits can be either permanent: they are preprogrammed in advance
- or Switched meaning the circuit is quickly built when it is needed and torn down when it is no longer needed.
116
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Permanent Virtual Circuits (PVC) vs. Switched Virtual Circuits (SVC)
- Permanent Virtual Circuit: works like a private line for a customer with an agreed-upon bandwidth availability. When a customer decides to pay for the CIR, a PVC is programmed for that customer to ensure it will always receive a certain amount of bandwidth
- Switched Virtual Circuits require steps similar to a dial-up and connection procedure. A circuit must be built
117
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: X.25
- X.25 is an older WAN protocol that defines how devices and networks establish and maintain connections.
- Like frame relay, X.25 is a switching technology that uses carrier switches to provide connectivity for many different networks.
118
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Asynchronous Transfer Mode (ATM)
- ATM is another switching technology, but instead of being packet-switching method, it uses a cell-switching method.
- ATM is a high-speed networking technology used for LAN, MAN, WAN, and service provider connection.
- Like frame relay, it is a connection-oriented switching technology, and creates and uses a fixed channel
119
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Asynchronous Transfer Mode (ATM): Quality of Service (QoS)
QoS is a capability that allows a protocol to distinguish between different classes of messages and assign priority levels.
- A technology that provides QoS allows an administrator to assign a priority level to time-sensitive traffic.
120
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Asynchronous Transfer Mode (ATM): Quality of Service (QoS) allows a service provider to guarantee a level of service to its customers. 4 different type of ATM QoS
- Constant bit rate (CBR): Connection oriented channel, provides a consistent data throughput for time sensitive apps
- Variable Bit Rate (VBR): connection oriented channel best used for relay insensitive applications. Data flow is uneven
- Unspecified Bit Rate (UBR): connectionless channel that does not promise a specific data throughput rate
- Available Bit Rate (ABR): connection oriented channel that allows the bit rate to be adjusted.
121
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: Asynchronous Transfer Mode (ATM): Quality of Service (QoS): 3 service level
- Best-effort service: no guarantee of throughput, delay, or delivery.
- Differentiated Service: more bandwidth, shorter delays, and fewer dropped frames.
- Guaranteed service: Ensures specific data throughput at a guaranteed speed. Time-sensitive traffic (voice and video) is assigned this classification
122
METROPOLITAN AREA NETWORKS (MAN): WAN Technologies: High-Serial Interface (HSSI)
- is an interface used to connect multiplexes and routers to high speed communications services such as ATM and frame relay.
- it supports speeds up to 52 Mbps
- this works at physical layer
