Lecture 16 Network Mgt, CDN, Load Balancing, CMS

Network Management

  • Definition: The overarching function of network management is to ensure efficient resource availability and consumption for users.

  • Tools: Network management tools include various hardware and software aimed at assisting network administrators.

Key Functions of Network Management

  1. Network Administration:

    • Tracking resources such as switches, routers, and servers.

    • Performance monitoring and software updates.

  2. Network Operation:

    • Ensures overall network performance is optimal.

    • Tasks include monitoring activities and proactively resolving issues.

  3. Network Maintenance:

    • Upgrades and fixes of network resources.

    • Involves collaborative work with network administrators.

    • E.g., replacing network gear like routers and switches

  4. Network Provisioning:

    • Configuring resources to support services (e.g., accommodating more users).

Managed vs. Unmanaged Devices

  • Managed Devices:

    • Offer configurability, management, and monitoring capabilities.

    • Higher initial cost but potential long-term savings.

    • Capable of reporting operational issues.

Standards and Protocols

  • SNMP (Simple Network Management Protocol):

    • The most commonly used protocol for managing network devices, utilizing software agents on managed devices.

    • Data management is done via the Management Information Base (MIB).

Designing for Network Performance

  • Allows manager to monitor performance and configuration on devices on network

  • system management software

  • application management software

Performance Management

  • Orgs use network operation centers (NOCs) to monitor networks using network management software

  • NOCs are a centralized location where IT teams monitor performance and health

  • SOC and NOC serve as the first line of defense against network attacks

Cloud Based Based Network Operations Center

  • Provides central dashboard for making connection between branch offices, data centers, and VPC,s

  • Network policies automate network management and security tasks

  • helps monitor network health, security, and performance

  • Link data centers, branch offices, and cloud resources to extend WAN to the cloud

Load Balancing

  • Definition: Load balancing efficiently distributes incoming network traffic across a group of backend servers.

  • Importance: Essential for modern high-traffic websites.

  • Importance: modern computing sometimes requires adding more servers

  • Role of Load Balancer:

    • Acts as a ‘traffic cop’ for server requests.

    • Routes client request across all servers

    • Maximizes utilization without overburdening a single server.

    • Automatically redirects traffic in case of server failure.

  • L4 and L7 switches can inspect TCP session state or HTTP session state

  • Perform mapping of requests to back end servers based on dynamically changing membership info

Load Balancer Functions

  1. Distributes client requests/network load across multiple servers.

  2. Ensures high availability by routing only to online servers.

  3. Flexible architecture to add or remove servers based on demand.

Load Balancing Algorithms

  • Round Robin: Sequentially assigns requests to servers.

  • Least Connections: New requests directed to server with least active connections. Computing capacity is factored into determining least conn

  • Least Time: Chooses based on fastest response and fewest connections.

  • IP Hash: Based on key defined Uses client IP for request distribution.

  • Random with Two Choices: Randomly picks two servers and sends the request to one determined by least connections.

Amazon Elastic Load Balancer(ELB)

  • distributes incoming application traffic across multiple targets, such as Amazon EC2 instances, containers, IP addresses, and Lamba function

  • handle varying load of app traffic in single availability zone or across multiple availability zone

Content Delivery Networks (CDNs)

  • Definition: A network of servers designed to deliver content rapidly and reliably.

  • Supplemental: Top global CND provides have spent billions to expand their massive infrastructure underneath growth of the Web

  • Supplemental: Layer in the internet ecosystem, content owners pay CDN operators to deliver content to end users

  • Supplemental: CDN pays ISP’s, carriers, and network operators for hosting it’s servers in data centers

  • Purpose: Offload web traffic, reduce latency, and provide scalability.

  • Market Impact: CDNs accounted for 80% of internet traffic by 2024.

Caching in CDNs

  • Goal: Minimize data transfer by storing copies of data to reduce repeated requests.

  • Keeps copies of data

  • Examples:

    • Web browsers cache recent items.

    • Web proxies save bandwidth by caching URLs.

    • save bandwith/ time when multiple people locally access same remote url

    • DNS resolvers cache resource records

    • Network file systems cache read/written data

How Caching Works

  • To improve speed and connectivity, CDN will place servers at exchange points between different networks

  • IXP’s are primary locations where IP’s connect to provide access to traffic on different networks

  • CND provider can reduce costs and transit times in high speed data delivery

Benefits of CDN

  • Reduced load time and latency.

  • Enhanced availability and reliability through load balancing and failover strategies.

  • Strategic placement in high-traffic locations aids in quick content delivery.

Reliability and Redundancy

  • Load balancing distributes network traffic evenly across several servers

  • intelligent failover provides uninterrupted service even if one or more of the CDN servers go offline due to hardware malfunctions

  • analyst routing transfers traffic to another available data center ensuring that no users loses access to the website

CDN Operations

  • Often make up 90% of web traffic

  • multimedia eliminates consistency problems

  • Content is cached at edge servers close to users.

  • Edge servers reduce the distance data travels, which improves load times significantly.

Without CDN

  • Amount of latency is increased by the total distance and time it takes each router to process the request

  • Once request is processes and responds, it sends info back through a similar sequence of routers

  • Measurement is recognized as RTT “round trip time”

Performance Comparison

  • reduction is distance between the client and content creates a 1900ms improvement in latency for static content, representing a 2 second improvement in load time

CDN Loading Content

  • Improves latency by pulling static content files from origin into distributed CDN network called caching

  • After TCP handshake, client makes http request to CDN network

  • If not cached CND will download content from the origin by making request between origin server and edge server

4 Steps during CDN caching

  1. When user request’s a webpage, the user request is routed to CDN’s nearest edge server

  2. edge server makes a request to the origin server for the content user requested

  3. the origin responds to the edge servers request

  4. the edge server responds to the client

CDN Edge Server

  • computer that exists at the logical extreme or ‘edge’ of a network

  • edge server often serves as connection between separate networks

  • primary purpose of CDN edge server is to store content as close as possible to requesting client machine

Differences between Edge Server and Origin Server

  • Origin Server

    • receives internet traffic when not using CDN

    • Each internet request must return to physical location of origin server

    • creates increase in load times thus increasing server from requesting client machine

  • Edge Server

    • store cached content in strategic locations to take load off servers

    • Reduce time for web resource to load

    • Moving images, HTML, Javascript, as close to requesting client machine

Content Management Systems (CMS)

  • Definition: Software for creating, managing, and modifying digital content.

  • Types:

    • Enterprise Content Management (ECM): Supports multiple users focused on document management, asset management, and records.

    • Web Content Management (WCM): Facilitates collaborative authoring for websites. May include text, embed graphics, photos, video, audio, maps

Installation Types

  1. On-Premises: Installed on local servers (e.g., WordPress.org, Drupal).

    • Approach usually taken by businesses that want flexibility

  2. Cloud-Based: Managed by vendors (e.g., WordPress.com, SquareSpace).

    • Cannot be modified for the customer

Core Features of CMS

  • Indexing, Search, and Retrieval: Index all data for Easy access to content via search functions and to search by attributes

  • Format Management: Converts various documents into web-friendly formats. E.g., HTML, PDF

  • Revision Control: Tracks and manages changes made to content.

  • Publishing Functionality: Users can create or modify content through templates and wizards.

Additional Features

  • SEO-friendly URLs.

  • Integrated help systems and discussion boards.

  • Group-based permission systems for content access control.

  • Easy wizzard based install and versioning procedures

  • Content hierarchy with unlimited depth and size

  • minimal server requirements

  • Support for multiple languages and minimal server requirements.

  • integrated audit logs

Next Steps

  • Prepare for Python for Networking Part 1 in the next lecture.