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Load balancing is process of balancing incoming requests to multiple machines, processes or services. In this video we will explain two types of load balancers, layer 4 and layer 7.

Chapters
0:00 Intro
6:00 L4 Load balancer
9:10 L4 Load Balancer Pros and Cons
16:18 Example L4 Load Balancer with HAPROXY
22:30 L7 Load Balancer
27:00 L7 Pros and Cons
31:00 Example L7 Load Balancer with HAPROXY
37:00 Summary



Layer 4 (4/3)
Take content forwards it based on basic rules, it knows ip and port and perhaps latency of the target service.

Layer 4 haproxy, NLB
Pros
great for simple packetlevel load balancing
Fast and efficient doesn’t look at the data
More secure as it cant really look at your packets. So if it was compromised no one can look
Uses NAT
One connection between client and server NATed
Cons
Cant do smart load balancing based on the content, such as switch request based on requested media type
Cant do microservices with this type
Has to be sticky as it is a stateful protocol (all segments)



Layer 7 (Nginx , haproxy)

This type of proxy actually looks at the content and have more context, it knows you are visiting the /users resources so it may forward it to a different server. Essential and Great for microservices , it knows the content is video:image etc..


it can also cache.. we cant really do caching on layer 4 because we have no clue whats in the packets.

But expensive because it has to decrypt and look and compute


Layer 4 haproxy, nlb
great for simple packetlevel load balancing
fast and efficient doesn’t look at the data
More secure as it cant really look at your packets. So id it was compromised no one can look
Uses NAT
One connection between client and server NATed
Layer 7 examples nginx
Smart routing based on the url (microservices) flexible
Provide caching
Expensive need to decrypt
Secuirty, you have to share your certificate with the load balancers. Id compromised attacker has access to all your data.
Proxy creates multiple connection (client to proxy/proxy to server)




Image thumbnails https://www.haproxy.com



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Hussein