Podcast
Questions and Answers
Which characteristic primarily distinguishes circuit switching from other network resource allocation methods?
Which characteristic primarily distinguishes circuit switching from other network resource allocation methods?
- Statistical multiplexing to maximize channel utilization.
- Shared resource availability, prioritizing burst data transfers.
- Exclusive allocation of resources, regardless of usage. (correct)
- Dynamic allocation of bandwidth based on immediate demand.
In Frequency Division Multiplexing (FDM), how is the available bandwidth divided among multiple users?
In Frequency Division Multiplexing (FDM), how is the available bandwidth divided among multiple users?
- Packets from different users are interleaved to maximize utilization.
- The entire bandwidth is dynamically allocated based on the demand of each user.
- Time slots are allocated to each user, allowing them to transmit sequentially.
- The frequency spectrum is divided into narrower bands, with each user assigned a specific band. (correct)
Under Time Division Multiplexing (TDM), what determines the maximum transmission rate available to each user?
Under Time Division Multiplexing (TDM), what determines the maximum transmission rate available to each user?
- The number of other users currently transmitting data.
- The width of the frequency band and the duration of their allocated time slot. (correct)
- The distance between the sender and receiver.
- The total bandwidth divided by the number of active users.
What is the primary role of Access Internet Service Providers (ISPs) in the Internet structure?
What is the primary role of Access Internet Service Providers (ISPs) in the Internet structure?
Why is the modern Internet described as a 'network of networks'?
Why is the modern Internet described as a 'network of networks'?
Which of the following best describes the fundamental challenge in creating the Internet's structure, given a multitude of access ISPs?
Which of the following best describes the fundamental challenge in creating the Internet's structure, given a multitude of access ISPs?
What is the main implication of the phrase 'network of networks' when describing the Internet?
What is the main implication of the phrase 'network of networks' when describing the Internet?
Consider the challenge of connecting millions of access ISPs. Which of the following strategies would be least effective in achieving a functional Internet structure?
Consider the challenge of connecting millions of access ISPs. Which of the following strategies would be least effective in achieving a functional Internet structure?
If the Internet were structured as a completely centralized network with a single controlling entity, which of the following would be the most likely consequence?
If the Internet were structured as a completely centralized network with a single controlling entity, which of the following would be the most likely consequence?
Imagine two access ISPs that refuse to peer with each other. What is a likely consequence for users of these ISPs in terms of accessing content?
Imagine two access ISPs that refuse to peer with each other. What is a likely consequence for users of these ISPs in terms of accessing content?
Based on the concept of a 'network of networks,' what is the most likely consequence of a new, localized internet service provider (ISP) emerging in a specific region?
Based on the concept of a 'network of networks,' what is the most likely consequence of a new, localized internet service provider (ISP) emerging in a specific region?
Considering the interconnected nature of the internet, what would be an advantage of having multiple competing ISPs?
Considering the interconnected nature of the internet, what would be an advantage of having multiple competing ISPs?
Given the 'network of networks' structure, what challenge might ISPs face when attempting to provide seamless global internet access?
Given the 'network of networks' structure, what challenge might ISPs face when attempting to provide seamless global internet access?
Imagine a scenario where a major ISP experiences a service disruption. How does the 'network of networks' architecture influence the impact of this disruption?
Imagine a scenario where a major ISP experiences a service disruption. How does the 'network of networks' architecture influence the impact of this disruption?
How would the creation of regulations that heavily favor larger ISPs affect the 'network of networks' structure?
How would the creation of regulations that heavily favor larger ISPs affect the 'network of networks' structure?
Which access network technology utilizes existing telephone lines to provide both data and voice services?
Which access network technology utilizes existing telephone lines to provide both data and voice services?
A home network connects to the internet through a local ISP. Which of the following represents the path the data takes to reach a content provider's network?
A home network connects to the internet through a local ISP. Which of the following represents the path the data takes to reach a content provider's network?
Which characteristic distinguishes a Wireless Local Area Network (WLAN) from a Wide-Area Cellular Access Network?
Which characteristic distinguishes a Wireless Local Area Network (WLAN) from a Wide-Area Cellular Access Network?
What is the primary function of a DSL Access Multiplexer (DSLAM) in a DSL network?
What is the primary function of a DSL Access Multiplexer (DSLAM) in a DSL network?
In cable-based access networks, what is the purpose of Frequency Division Multiplexing (FDM)?
In cable-based access networks, what is the purpose of Frequency Division Multiplexing (FDM)?
An enterprise network connects to the internet. Which path would data likely take when accessing a remote datacenter?
An enterprise network connects to the internet. Which path would data likely take when accessing a remote datacenter?
A user experiences slow internet speeds on their home WiFi network. What is the most likely cause related to WLAN technology?
A user experiences slow internet speeds on their home WiFi network. What is the most likely cause related to WLAN technology?
Which of the following is a characteristic of DSL technology regarding data transmission rates?
Which of the following is a characteristic of DSL technology regarding data transmission rates?
A mobile carrier is upgrading its network infrastructure. Which technology upgrade would provide the most significant increase in data transmission rates for its users?
A mobile carrier is upgrading its network infrastructure. Which technology upgrade would provide the most significant increase in data transmission rates for its users?
In a typical home network setup with both wired and wireless devices, where does the access network begin?
In a typical home network setup with both wired and wireless devices, where does the access network begin?
Which of the following transmission scenarios would likely result in queuing delays within a packet-switched network?
Which of the following transmission scenarios would likely result in queuing delays within a packet-switched network?
A host needs to transmit a 4000-bit message across a network with a link transmission rate (R) of 2 Mbps. If the message is divided into 4 packets, each with 1000 bits, what is the transmission delay for each packet?
A host needs to transmit a 4000-bit message across a network with a link transmission rate (R) of 2 Mbps. If the message is divided into 4 packets, each with 1000 bits, what is the transmission delay for each packet?
In a packet-switched network, what is the primary role of the 'forwarding' function within a router?
In a packet-switched network, what is the primary role of the 'forwarding' function within a router?
What is the key difference between packet switching and circuit switching?
What is the key difference between packet switching and circuit switching?
Why is it essential for a host to break application messages into packets before transmitting them over a network?
Why is it essential for a host to break application messages into packets before transmitting them over a network?
Consider a network path with two links. The first link has a transmission rate of 10 Mbps, and the second link has a transmission rate of 2 Mbps. What is a potential bottleneck in this scenario?
Consider a network path with two links. The first link has a transmission rate of 10 Mbps, and the second link has a transmission rate of 2 Mbps. What is a potential bottleneck in this scenario?
What is the role of the 'routing algorithm' in a network core?
What is the role of the 'routing algorithm' in a network core?
An enterprise network connects to the internet through an institutional router. What is the function of this router?
An enterprise network connects to the internet through an institutional router. What is the function of this router?
Which of the following best describes the concept of 'link bandwidth'?
Which of the following best describes the concept of 'link bandwidth'?
In the context of network access technologies, what is the primary difference between Ethernet and WiFi?
In the context of network access technologies, what is the primary difference between Ethernet and WiFi?
What is the primary purpose of an Internet Exchange Point (IXP)?
What is the primary purpose of an Internet Exchange Point (IXP)?
Which of the following best describes the role of tier-1 ISPs within the internet structure?
Which of the following best describes the role of tier-1 ISPs within the internet structure?
How do content provider networks (like Google or Netflix) improve user experience?
How do content provider networks (like Google or Netflix) improve user experience?
Which scenario exemplifies the use of a peering link?
Which scenario exemplifies the use of a peering link?
What is a key characteristic of a 'network of networks' architecture of the Internet?
What is a key characteristic of a 'network of networks' architecture of the Internet?
What is a potential benefit for a content provider in operating its own network?
What is a potential benefit for a content provider in operating its own network?
Consider a scenario where a user accesses a website hosted on a server within the same regional ISP's network. Which path is the traffic likely to take?
Consider a scenario where a user accesses a website hosted on a server within the same regional ISP's network. Which path is the traffic likely to take?
What is the significance of a 'point-of-presence' (POP) within an ISP's network?
What is the significance of a 'point-of-presence' (POP) within an ISP's network?
How does the presence of regional ISPs change the typical path of internet traffic?
How does the presence of regional ISPs change the typical path of internet traffic?
Consider two ISPs, one a tier-1 provider and the other a regional ISP. What is the most likely relationship between them?
Consider two ISPs, one a tier-1 provider and the other a regional ISP. What is the most likely relationship between them?
What is the most likely reason for an ISP to establish a peering agreement with another ISP at an IXP?
What is the most likely reason for an ISP to establish a peering agreement with another ISP at an IXP?
Which of the following actions would most likely improve network performance for users of a content provider network?
Which of the following actions would most likely improve network performance for users of a content provider network?
Why might a large social media company (like Facebook) choose to operate its own network infrastructure?
Why might a large social media company (like Facebook) choose to operate its own network infrastructure?
What is the primary distinction between an access network and a tier-1 ISP network?
What is the primary distinction between an access network and a tier-1 ISP network?
If a regional ISP wants to improve the resilience of its network, what would be the most effective strategy related to IXPs?
If a regional ISP wants to improve the resilience of its network, what would be the most effective strategy related to IXPs?
Flashcards
Internet Access
Internet Access
The way users connect to the Internet, often through ISPs.
Network of Networks
Network of Networks
A collection of interconnected networks.
Access ISPs
Access ISPs
Internet Service Providers; companies providing internet access.
Internet Structure
Internet Structure
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Connecting ISPs
Connecting ISPs
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Circuit Switching
Circuit Switching
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Frequency Division Multiplexing (FDM)
Frequency Division Multiplexing (FDM)
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Time Division Multiplexing (TDM)
Time Division Multiplexing (TDM)
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National/Global ISP
National/Global ISP
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Local/Regional ISP
Local/Regional ISP
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Digital Subscriber Line (DSL)
Digital Subscriber Line (DSL)
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DSLAM
DSLAM
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Wireless Access Network
Wireless Access Network
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Wireless Local Area Networks (WLANs)
Wireless Local Area Networks (WLANs)
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Wide-Area Cellular Access Networks
Wide-Area Cellular Access Networks
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802.11
802.11
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Enterprise Network
Enterprise Network
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Access Network
Access Network
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Internet Service Provider (ISP)
Internet Service Provider (ISP)
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Global ISP
Global ISP
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ISP Competitors
ISP Competitors
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Hybrid Network
Hybrid Network
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Ethernet
Ethernet
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WiFi
WiFi
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Packet
Packet
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Link Transmission Rate (R)
Link Transmission Rate (R)
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Network Core
Network Core
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Packet-Switching
Packet-Switching
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Store-and-Forward
Store-and-Forward
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Queuing Delay
Queuing Delay
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Routing Algorithm
Routing Algorithm
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Internet Exchange Point (IXP)
Internet Exchange Point (IXP)
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Regional Network
Regional Network
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Content Provider Network
Content Provider Network
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Tier-1 ISPs
Tier-1 ISPs
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Level 3 (now Lumen)
Level 3 (now Lumen)
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Sprint (now T-Mobile)
Sprint (now T-Mobile)
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AT&T
AT&T
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NTT
NTT
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Content Provider Networks
Content Provider Networks
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Peering Links
Peering Links
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POP (Point of Presence)
POP (Point of Presence)
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Packet Loss
Packet Loss
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Delay (Latency)
Delay (Latency)
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Study Notes
Overview of Computer Networks
- Interconnected networks significantly shape modern daily life.
- Key network types include LANs (Local Area Networks), WANs (Wide Area Networks), and the Internet
- Networks comprise a network edge and a network core
The Internet
- It consists of billions of interconnected computing devices such as hosts, which include end systems.
- Hosts run network apps located at the Internet's "edge."
- Packet switches forward data in chunks and include routers and switches.
- Communication links use fiber, copper, radio, or satellite with a specific transmission rate, called bandwidth.
- Internet protocols are prevalent, controlling the sending and receiving of messages.
- Examples of established protocols are HTTP, streaming video, Skype, TCP, IP, WiFi, 4G, and Ethernet.
- Internet standards make use of RFC (Request for Comments).
- Standards are maintained and developed by IETF (Internet Engineering Task Force).
- Internet structure includes
- Network edge made up of clients and servers (often in data centers)
- Access networks using physical media (wired and wireless communication links)
- Network core made up of interconnected routers, and networks.
- End systems connect to edge routers through residential, enterprise, or mobile carrier networks based on access networks.
- Wireless LANs typically span a building (~100 ft), exemplified by 802.11b/g/n (WiFi) with transmission rates of 11–450 Mbps.
- Wide-area cellular networks, managed by mobile operators (over 10's of kms) offer speeds of 10's Mbps using 4G (or 5G) technologies.
- Key aspects of Internet service include
- Provision of infrastructure for web, streaming, email, gaming, e-commerce, social media, appliances, and other applications
- Provision of a programming interface enabling distributed applications via "hooks" that facilitate connection and transport service use
Protocol Elements
- Has three key components: source/sender, destination/receiver, and communication channel/media.
- The actions taken for message transmission and receipt are determined by these components.
- Internet communications follow protocols, which define a common format for all messages.
Data Transmission in Networks
- Hosts perform functions related to a sending operation
- Application messages are converted into packets of a certain length, L.
- Packets are transmitted into an access network with a transmission rate, R.
- The link transmission rate, also termed link capacity or link bandwidth, determines transmission time.
- The time needed to transmit an L-bit packet across a link is L (bits) / R (bits/sec).
Network Core
- The network's interconnection allows packet switching, where hosts split application-layer messages into packets.
- Each packet is transferred from one router to the next along the path from source to destination at full link capacity.
- Core functions consists of forwarding local actions to move arriving packets and global actions to determine source-destination paths
Switching Methods
- Store-and-forward packet switching completely transmits each packet to its destination
- Circuit switching allocates end-to-end resources for a "call" duration.
- Each link has four circuits, and assigned circuits are reserved for the call duration.
- If a circuit segment is not used by a call, it remains idle without sharing.
- There also exists
- Frequency Division Multiplexing (FDM)- Optical or electromagnetic frequencies into narrow bands; each call gets its own max rate frequency band.
- Time Division Multiplexing (TDM)- Time is divided into slots. Calls get allocated periodic slots, enabling max frequency band transmission, but only during allocated slot times.
Internet Structure
- Connects hosts through ISPs (Internet Service Providers) via access networks.
- Access ISPs interconnect to enable packet sending between hosts.
- Resulting "network of networks" relies on economic and policy-based evolution
- To maintain order, connects each access ISP to one global transit ISP- relies on economic agreement.
- Multiple global ISPs arise to promote competition.
- ISPs connect using Internet exchange points (IXPs) and peering links, enabling direct traffic exchange.
- Regional networks connect access networks which improves distance and performance.
- Content provider networks host or operate services close to end users.
- Small # of connected commercial/tier networks which allow content sharing.
Network Performance
- Performance can depend mainly on packet loss and packet delay
- Packet loss and delay can occur due to
- Packets waiting in router buffers that causes a queue
- Arrival rate exceeding link capacity that causes packet loss
- The four sources of Pack delay include
- Nodal processing (dproc)
- Pequeueing delay (dqueue)
- Transmission delay (dtrans)
- Propagation delay (dprop)
- Total Delay dnodal = dproc + dqueue + dtrans + dprop
- Retransmitting a lost packet may not occur due to finite loss of waiting
Throughput
- The rate that bits are transmitted from sender to receiver over a period of time.
- Can be instantaneous or average bit rate.
Network Standards
- Internet standards are specifications that are useful and adhered to internally which form regulations
- Request for Comments are used to determine whether the specifications is adequate and useful
- Internet Draft is a working document with limited and temporary status
- Internet Engineering Task Force (IETF) develops and maintains standards in the standards setting organization.
Organizations
- Internet Engineering Task Force (IETF) develops and maintains standards in the standards setting organization.
- The Institute of Electrical and Electronics Engineers (IEEE) is a related organization devoted to electrical, electronics, and computer engineering.
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