Networking 101 - Load Balancers

Summary

The video script explains the concept and utility of load balancers in managing web traffic and ensuring high availability. It describes how a single server's finite resources can be insufficient, leading to the need for load balancing across multiple servers to handle increased traffic and maintain uptime. The script also touches on load balancer strategies like round-robin and least connections, and the importance of redundancy with multiple load balancers.

Takeaways

• 🌐 A load balancer is a device or software that distributes network traffic across multiple servers to ensure no single server bears too much load.
• 💡 Load balancers help prevent server downtime by allowing traffic to be rerouted to other servers if one server fails or requires maintenance.
• 🔁 They can improve website performance by spreading the load, thus allowing more connections to be handled by utilizing the resources of multiple servers.
• 🛠️ Load balancers enable maintenance and updates to be performed on servers without affecting the availability of the website or service.
• 🔄 Round-robin is a simple load balancing method where requests are distributed in a sequential manner across servers.
• 📉 Least connections is a more advanced method where the load balancer sends traffic to the server with the fewest current connections.
• 💻 Least loaded is an intelligent method where the load balancer sends traffic to the server with the most available resources, like CPU and memory.
• 🔀 Load balancers can dynamically add or remove servers to adjust to changing demand, ensuring optimal resource utilization.
• 🔒 Typically, load balancers are deployed in pairs for redundancy, ensuring that if one fails, the other can take over without service interruption.
• 🔧 They are crucial for high availability and scalability in web services, allowing businesses to grow their capacity and maintain uptime.

Q & A

What is a load balancer?

A load balancer is a piece of hardware or software that distributes network traffic across multiple servers to ensure no single server becomes overwhelmed, thus improving response times and system availability.

Why is it important to have a load balancer?

Load balancers are important because they help in managing finite server resources, ensuring no downtime, and providing redundancy to handle increased traffic or server maintenance without affecting the end-users.

What are the limitations of hosting a website on a single server?

Hosting a website on a single server has limitations such as finite processing power, memory, disk space, and network connections, which can lead to bottlenecks and potential downtime.

How does a load balancer help in handling more connections?

A load balancer helps in handling more connections by distributing the load across multiple servers, allowing the system to utilize the combined resources of all servers, thus increasing the capacity to serve more users.

What is the benefit of having multiple servers behind a load balancer?

Having multiple servers behind a load balancer allows for redundancy and fault tolerance. If one server fails, the load balancer can redirect traffic to the remaining operational servers, ensuring continuous service.

How does a load balancer facilitate maintenance without downtime?

A load balancer facilitates maintenance by allowing administrators to take a server offline for maintenance without affecting the overall service. Traffic is simply redirected to other servers in the pool.

What is round-robin load balancing?

Round-robin load balancing is a method where the load balancer distributes traffic sequentially across servers in a circular order, ensuring an equal distribution of requests.

What is least connections load balancing?

Least connections load balancing is a method where the load balancer sends traffic to the server with the fewest active connections, aiming to balance the load based on the number of connections rather than equal distribution.

What is least loaded load balancing?

Least loaded load balancing is a method where the load balancer analyzes the resource usage of servers, such as CPU and memory, and directs traffic to the server with the most available resources to ensure optimal performance.

Why would a company need to scale their server capacity?

A company may need to scale their server capacity to handle increased demand, improve performance, or to ensure that their services remain available and responsive during peak traffic times.

How does having redundant load balancers contribute to system reliability?

Having redundant load balancers contributes to system reliability by providing a backup in case one load balancer fails. This ensures that traffic can still be distributed among servers, maintaining service availability.

Outlines

00:00

💻 Introduction to Load Balancers

This paragraph introduces the concept of a load balancer in the context of a company hosting a website like WWE XYZ. It explains the limitations of a single server in terms of processing power, memory, disk space, and network connections. The paragraph emphasizes the need for load balancers due to finite resources and the desire for no downtime. It describes how load balancers distribute traffic across multiple servers to increase capacity and maintain uptime, even when one server fails. The concept of maintenance and updating servers without affecting service is also discussed, along with the ability to scale up by adding more servers as demand increases.

05:03

🔄 Advanced Load Balancing Techniques

The second paragraph delves into more sophisticated load balancing methods, such as round-robin and least connected algorithms. It explains how round-robin distributes requests evenly across servers, while the least connected method sends traffic to the server with the fewest current connections. The paragraph also introduces the idea of load balancing based on the least loaded servers, which involves assessing CPU and memory usage to determine which server can handle more traffic. This approach ensures efficient resource utilization and optimal distribution of workloads.

Keywords

💡Load Balancer

A load balancer is a networking device or software that distributes network or application traffic across multiple servers. In the context of the video, it's described as a piece of hardware that directs traffic to multiple servers, ensuring no single server becomes overwhelmed. The video emphasizes its importance in maintaining uptime and distributing the load to prevent any server from reaching its finite resources.

💡Finite Resources

Finite resources refer to the limited capacity of a server, including processing power, memory, and disk space. The video script mentions that a single server has a finite number of resources, which can be a bottleneck for handling high traffic, hence the need for a load balancer to distribute the load across multiple servers.

💡Downtime

Downtime is the period during which a system or service is not operational. The script discusses the importance of minimizing downtime for customers, which is a key reason for using load balancers. By distributing traffic across multiple servers, the system can continue to operate even if one server goes down, thus reducing downtime.

💡TCP/IP Protocol Suite

TCP/IP stands for Transmission Control Protocol/Internet Protocol, which is the foundational communication protocols used for transmitting data over the internet. The script touches on network limitations in terms of the TCP/IP protocol suite, indicating the technical constraints that can be overcome by using load balancers to manage connections more efficiently.

💡Round-Robin Load Balancing

Round-robin is a method of load balancing where each request is served by the next server in a sequential order. The video uses the analogy of dealing cards for a card game to illustrate how requests are evenly distributed among servers, ensuring no single server is overburdened.

💡Least Connected

Least connected is an advanced load balancing algorithm where traffic is directed to the server with the fewest current connections. The video script explains this as a strategy to optimize the distribution of traffic, ensuring that servers with fewer active connections receive more incoming requests.

💡Least Loaded

Least loaded is another load balancing algorithm that directs traffic to the server with the most available resources, such as CPU and memory. The video script describes how a load balancer can query servers for their current load and then send traffic to the least loaded server, optimizing resource utilization.

💡Scheduled Maintenance

Scheduled maintenance refers to the planned downtime for performing routine checks, updates, or repairs on systems. The video script mentions that load balancers allow for scheduled maintenance without affecting service availability, as traffic can be redirected to other operational servers.

💡Redundant Load Balancers

Redundant load balancers are additional load balancers that provide backup in case the primary one fails. The script briefly mentions the concept of having a pair of load balancers to ensure that even if one fails, the other can take over, maintaining the system's uptime and reliability.

💡Scalability

Scalability refers to the ability of a system to handle a growing amount of work by adding resources. The video script discusses how load balancers enable scalability by allowing additional servers to be added to the system to handle increased demand, thus improving capacity and uptime.

💡Network Limitations

Network limitations refer to the constraints in a network's ability to handle data transfer, such as bandwidth or connection limits. The video script points out that a single server has network limitations, which can be mitigated by using load balancers to distribute traffic across multiple servers, thereby overcoming these limitations.

Highlights

Load balancers distribute network traffic to optimize resource use and maximize throughput.

A single server has finite resources such as processing power, memory, and disk space.

Network limitations include the number of TCP/UDP connections a server can handle.

Load balancers help prevent downtime by distributing traffic across multiple servers.

Multiple servers allow for load sharing and handling more connections.

Load balancers enable maintenance without affecting service availability.

Servers can be taken down for maintenance without customer disruption.

Load balancers support scaling by adding more servers to meet increased demand.

Redundant load balancers ensure high availability and fault tolerance.

Round-robin load balancing distributes requests sequentially across servers.

Least connections method directs traffic to the least busy server.

Least loaded method sends traffic to the server with the most available resources.

Load balancers can dynamically adjust traffic distribution based on server load.

Load balancers are crucial for maintaining uptime and providing a consistent user experience.

Load balancing strategies can be simple or complex, depending on the needs.

Load balancers play a key role in high-availability architectures.

The video provides a basic overview of load balancers and their practical applications.

Transcripts

[Music]

all right so what's a load balancer know

would you use one okay so let's say

you're a company and you host WWE XYZ

comm that's your your main website

people come on there and buy whatever

widgets you happen to sell and that's

what you make all your money off of so

you've got this website sitting in your

data center hosted on a server for now

the problem with that is down here on

number one that server has finite

resources what do I mean by that well

one individual server only has so much

processing power so much memory so much

disk space

there's also Network limitations in

terms of the tcp/ip protocol suite in

terms of the number of actual

connections they can serve up whether

it's TCP UDP or whatever so there's a

problem with putting everything putting

all your eggs on one in one basket for

lack of a better term so you have a

physical server there's a finite number

of resources the second thing and the

biggest is no downtime you know how many

different companies out there who run

their networks don't allow you know any

plan downtime or any maintenance from

the driver were very very short and

there are very odd hours of the of the

night so to minimize any potential

outages to customers so that's the big

thing here finite resources no downtime

well how does that plan to the load

balancer up here so load balancers a

it's a piece of hardware yes it can be a

virtual software construct inside of a

virtual environment but for the purposes

of this video we'll just say it's a

physical piece of hardware on that

physical piece of hardware you have

connections going to multiple servers

typically maybe they're not physically

connected into it but logically they

kind of fall behind the actual load

balancer and you know why would I have

multiple servers well I'll go back to

number one finite resources what if I

can host my WWE

z.com website on more than one server

what if I could put it on these three

servers right here well if I can do that

then I can share the load I can balance

the load across those three systems so I

can handle far more connections because

now I have three servers instead of one

so I can use all of their resources

that's the first thing and the second

thing with no downtime if I have a

problem with one of these servers I can

actually shut it down and continue to

serve traffic to the other two servers

that are actually remaining so that's

kind of the basics in it in a nutshell

of you know what a load balancer is and

why why you would actually use it so

things like I mentioned maintenance so

let's say you know server one has an

actual problem and I need to take it

down well I can remove server one from

the actual load balancer path continue

to serve up connections with two and

three and no one's the wiser no one

knows it's down I can work on it do

whatever I want well let's say it's not

just analogous say your scheduled

maintenance you know you get a patch

server you get a the basic care and

feeding that goes along with maintaining

servers it happens

so there's on occasion I have to take

these things out what if I released you

know a new version of the actual website

of the application I'll take it out

update it put it back in take the other

ones out update them put them back in

operation and so forth and so on well so

I've got my two servers let's say this

guy over here is crashed another thing I

can do is I can start adding additional

servers let's say demand increases and I

need to add you know I need to double or

triple my capacity well I can kind of

inject servers into this load balancer

and have it start sending traffic to all

these different servers you know and get

even greater capacity and even greater

uptime capabilities because you know

I've got at least here five servers

right now that can that can handle the

load

and I have one load balancer drawn here

typically you'd have to I'd have a pair

of them and each server would be

connected to both load balancers either

physically or there's some logical flow

in the network so I would have redundant

load balancers I just didn't draw it

because I'm dealing with a finite amount

of space all right so that's basically

the concept behind a load balancer now

there's some more intelligent things you

can do with it you can do what's called

a round-robin load balancing where you

know I send a request to one server and

then to the next one to the next one

then to the next one and so forth or it

just kind of goes around in a circle and

you know kind of one here one here one

here almost like you're dealing cards

for a card game or something but it

doesn't have to be that simple you know

I can use something is I can do least

something like least connected well what

if I the load balancer looks at all

these servers right here finds out which

one has the fewest number of connections

and then sends traffic to it but I could

even go a step further than that I could

say now I don't want to do at least

connected them I want to do the least

loaded so I can query these servers and

find out well you know how much CPU load

is on number six and how much memory is

it using and what about you know number

five how much CPU how much memory and so

forth and so on or how many you know

whatever whatever value or variable I

want to look at and then I can say okay

well two three four and five are kind of

busy but six six has the most resources

free so I'm going to start just sending

traffic to six until it kind of normals

out then I'll already assess and and go

back and look at it that way so that's

kind of you know just a couple of

minutes the overview of of load

balancers and kind of what they do and

it's a fairly basic purpose