Questions and Answers
What is the primary characteristic that distinguishes a local area network (LAN) from a wide area network (WAN)?
What is the main reason why a service provider is needed for a wide area network (WAN)?
What was a common technology used in the early days of wide area networks (WANs)?
What is a limitation of using the internet for wide area network (WAN) connectivity?
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What is an example of a technology that is no longer commonly used in wide area networks (WANs)?
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What is the primary difference between a local area network (LAN) and a wide area network (WAN) in terms of geography?
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What is an advantage of using a service provider for wide area network (WAN) connectivity?
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What is a key characteristic of a wide area network (WAN)?
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What is the primary purpose of the underlay in a wide area network?
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What is a limitation of using GRE tunneling in a wide area network?
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What is the primary purpose of IP SEC in a wide area network?
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What type of architecture is often used in campus networks?
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What is a characteristic of the two tier architecture used in data centers?
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What is a challenge faced by many network architectures?
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What is the purpose of the overlay network in a wide area network?
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What is a service provider's role in a wide area network?
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What is a benefit of using IP SEC with GRE tunnels in a wide area network?
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What is a type of technology used by service providers to facilitate connectivity in a wide area network?
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Study Notes
Local Area Network (LAN)
- A LAN represents high-speed communications in a small geographic area (e.g., within a building or between a couple of buildings).
- Cabling (copper, fiber, or wireless) connects devices for high-speed connectivity between nodes.
Wide Area Network (WAN)
- A WAN connects devices over a large geographic area (e.g., across the United States, over 2000 miles).
- Requires help from a service provider to provide connectivity.
- Involves the underlay (physical networks and connectivity) and the overlay (logical connections on top of the underlay).
WAN Technologies
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Leased lines (slow and serial) were used in the past.
In this context, "serial" refers to the method of data transmission over the leased lines. Data is sent one bit at a time in a sequential manner, like a single-lane road where cars pass one by one. This is in contrast to parallel transmission, where multiple bits are sent simultaneously, like a multi-lane highway. Serial transmission is typically slower than parallel transmission.
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Frame relay was a new technology introduced in the 90s, but it's now an old technology.
Frame relay is a way to send data between computers over a wide area network (WAN). Think of it like a mailing system where information is broken into packets (like letters) and sent through a shared network (like a post office). It was popular in the 90s because it was faster and cheaper than older methods, but now there are newer technologies that people prefer to use.
Think of Frame Relay as a method for sending data between computers over a wide area network (WAN) using a shared network, much like how a postal system works for sending mail. Here's a simpler breakdown:
1. Data Packets: Imagine information as being broken down into packets, similar to how you might put a letter into an envelope. Each packet of data includes not only the actual information being sent but also some additional information called a "header," which acts like the address on an envelope, telling the network where to send it.
2. Shared Network: Frame Relay networks share the same physical infrastructure among many users. Think of this like a large post office that sorts and routes mail for many different people. Similarly, Frame Relay takes these data packets from various sources and directs them to their correct destinations through a system of switches and routers.
3. Virtual Circuits: In Frame Relay, virtual circuits are established between sending and receiving computers. These are logical paths across the network, similar to a designated postal route, which ensure that packets are delivered correctly. There are two types of virtual circuits:
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Permanent Virtual Circuits (PVCs): Always available between two points.
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Switched Virtual Circuits (SVCs): Established on an as-needed basis and torn down after the transmission is complete.
Yes, Frame Relay can be understood as a specialized, restricted network service not accessible to the general public through the public internet. It is primarily designed for enterprise-level WAN communication, connecting multiple LANs across different locations within an organization's internal network or between the organization and its branches. Unlike broadband internet services provided by ISPs, Frame Relay requires specific configuration and contracts with telecom providers, making it exclusive to subscribing enterprises rather than being widely available to the general public.
4. Efficiency: Unlike older methods of data communication, which often used dedicated lines even if no data was being sent, Frame Relay makes efficient use of the network by only using bandwidth as needed. This shared approach reduces costs and allows for higher speeds.
So, Frame Relay was popular because it optimized the way data was sent over large distances by efficiently sharing network resources among many users. However, it has since been largely replaced by newer technologies like MPLS (Multiprotocol Label Switching) and broadband internet, which offer even better performance and reliability.Today, WANs can use the public cloud (internet) or a service provider for connectivity.
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MPLS is a technology used by service providers to facilitate WAN connectivity.
- MPLS, or Multiprotocol Label Switching, is a technology that service providers use to efficiently direct data across wide area networks (WANs). Think of it like a highway system for data: rather than each packet of information needing to stop and check the route at every turn, MPLS assigns labels to packets. These labels tell network devices how to forward the packets along predefined paths, much like following road signs on a highway. This process speeds up data transmission, reduces congestion, and improves the overall quality and reliability of the network. By bypassing traditional routing protocols, MPLS enables a more deterministic and efficient forwarding of packets, allowing service providers to guarantee a specific level of service quality to customers. Additionally, MPLS supports various network protocols, including IP, IPv6, and Ethernet, making it a versatile technology for deploying WANs.
WAN Architecture
In a WAN architecture, MPLS plays a crucial role in shaping the overall network design. To understand MPLS in this context, it's essential to first consider the key components of a WAN architecture. Typically, a WAN consists of multiple sites, connected through a backbone network and access networks. The backbone network serves as the primary path for data transmission, whereas access networks facilitate communication between individual sites. Within this framework, MPLS is often used to establish a virtual private network (VPN), which enables secure and dedicated connections between different sites. This VPN is particularly useful for organizations with multiple locations, as it ensures a consistent level of service across the entire network.
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Multiple sites (e.g., site 10, site 20, site 30, site 40) are connected using underlay networks (physical connections).
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MPLS achieves this by establishing a layer 2 (L2) and layer 3 (L3) model, where the underlay network provides a stable physical infrastructure, and the overlay network, or Virtual Private Network (VPN), is a logical connection that operates on top of it. This decoupling enables flexible network design and management. GRE tunneling is an option for creating logical paths between sites.
An overlay network essentially builds a secondary layer on top of an existing network infrastructure. To expand on the city roads analogy, imagine that the physical network consists of all the roads, highways, and pathways already established. These represent the physical hardware like cables, routers, and switches that make up the core of the internet or your network.
Now, visualize the overlay network as a network of tunnels, bridges, or virtual pathways that can be dynamically created, modified, or removed without physically changing the roads. These virtual pathways allow data to bypass or reroute around congested areas, much like taking a less crowded alternate route during rush hour.
Overlay networks can span multiple physical networks or create virtual links across different geographic locations, making it seem as if distant computers are on the same local network. This abstraction provides several benefits:
1. Enhanced Flexibility: It allows for quick adjustments in response to changing network loads, user demands, or faults in the physical network.
2. Improved Security: VPNs (Virtual Private Networks), a common type of overlay network, encrypt data and create private communication channels over a public network, safeguarding the data from unauthorized access.
3. Resource Optimization: Overlay networks can optimize resource usage by finding and using the most efficient paths for data transmission. This helps in balancing loads and reducing congestion.
4. Simplified Management: Network administrators can manage network policies, configurations, and troubleshooting from a centralized point, without needing to make physical changes to the underlying infrastructure.
Technologies such as MPLS (Multiprotocol Label Switching), SDN (Software-Defined Networking), and various tunneling protocols like GRE (Generic Routing Encapsulation) and IPsec all utilize the concept of overlay networks to improve performance, security, and manageability.
By leveraging these virtual pathways, overlay networks provide a versatile and powerful way to meet modern networking demands while keeping the existing physical infrastructure intact and fully utilized.GRE tunnels can be encrypted using IP SEC to protect data packets.
Network Architectures
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Four network architectures have been identified: three-tier, two-tier, storage networks, and wide area networks.
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Three-tier architecture is popular in campus networks for interconnectivity and external access.
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Two-tier architecture is used in data centers for high East-West traffic.
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storage Networks
Storage networks have their own set of technologies, designed specifically for managing and sharing data across a network. These technologies enable efficient data transfer, replication, and retrieval, ensuring seamless data access and storage operations. Some key components of storage networks include storage-area networks (SANs), network-attached storage (NAS) devices, and distributed file systems. These technologies are optimized for tasks such as data backup, archiving, and data replication, allowing for greater data availability and reduced storage costs.
Storage-Area Networks (SANs) and Network-Attached Storage (NAS) devices are two key technologies used in storage networks, each optimized for different use cases. Here’s a comparison and contrast between SANs and NAS:
Architecture:
- SAN: SAN operates at the block level, providing access to raw storage volumes that can be partitioned and formatted as needed by the operating systems. It uses high-speed network technologies like Fibre Channel or iSCSI.
- NAS: NAS operates at the file level, providing access to data storage over standard network protocols like NFS, SMB/CIFS. NAS devices typically come with their own operating systems and file systems.
Performance:
- SAN: Designed for high performance and low latency, SANs are ideal for applications requiring fast data access, such as databases and mission-critical applications.
- NAS: While NAS can offer good performance, it generally doesn't match the speed and low latency of SANs. It is suitable for tasks like file sharing, home directories, and less latency-sensitive data workloads.
Scalability:
- SAN: SANs are highly scalable, capable of connecting multiple servers to a large pool of shared storage. This is suitable for enterprise environments with large data needs.
- NAS: NAS can also be scaled, but it is generally easier to add more NAS devices rather than expanding a single NAS. It is often used in small to medium-sized businesses.
Management:
- SAN: Typically requires specialized IT knowledge to manage, involving complex configurations and maintaining a dedicated network separate from the general data network.
- NAS: Usually simpler to manage, using common network management techniques. User-friendly interfaces and straightforward integration with existing networks make NAS devices more accessible to general IT staff.
Use Cases:
- SAN: Best suited for data-intensive applications such as databases, virtualization, high-performance computing, and large-scale business applications.
- NAS: Ideal for file storage and sharing, data archiving, backups, and media streaming, addressing the needs of collaborative work environments and general storage access.
Cost:
- SAN: Generally more expensive to deploy and maintain due to the need for specialized hardware, high-speed networking equipment, and expertise.
- NAS: Typically more cost-effective, with lower upfront costs and minimal requirements for specialized knowledge and equipment.
In summary, SANs and NAS serve distinct purposes within storage networks. SANs are optimized for high performance and enterprise-level scalability, making them suitable for critical applications. NAS devices offer ease of use, simplified management, and cost-efficiency, making them ideal for general-purpose file storage and sharing.
Challenges and Solutions
- Manual labor is required to implement WAN architectures, which can be time-consuming.
- Software-defined networking (SDN) and software-defined wide area networking (SD-WAN) are emerging solutions to simplify network management.
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Description
This quiz covers the basics of local area networks (LANs), including high-speed communications in small geographic areas and different types of cabling.
