[1Day-1CS] Devices that handle each layer

2023-06-18 Merge content from previous posts for content consistency

Devices that handle the application layer

L7 switch: also known as a load balancer, a device that balances the load on servers

• Switch: A telecommunications network device that connects multiple devices and mediates data communications, sending electrical signals only to the connected ports to transmit data.

• Aimed at increasing the amount of traffic a system can handle

• Distribute traffic based on URLs, servers, caches, cookies, etc.

• Has filtering capabilities to keep out unnecessary external data

• Allows you to monitor traffic

= Health Check excludes failed servers from traffic distribution via a health check

Difference between L4 and L7 switches

• L4 switches are devices that handle the transport layer and cannot be used for streaming-related services.

• Message-based unawareness, IP & Port based traffic distribution

• In cloud services, load balancing with L7 switches is done with ALB (Application Load Balancer) component and load balancing with L4 switches is done with NLB (Network Load Balancer) component

Health Check

Sending requests to the server repeatedly by setting the transmission cycle and number of retransmissions, etc.

• Appropriate enough to not overload the server

• Sending requests in different ways and determining if they are processed correctly.

Server redundancy with load balancers

Provide virtual IPs based on 2 or more servers and provide stable services based on them

Server redundancy is necessary because the service must continue even if a specific server fails.

Devices that handle the Internet layer

Router: connects, divides, and separates multiple networks. L3 switch: L2 switch + router

Devices that handle the data link layer

L2 switch: Manages the Mac addresses of devices, sends packets, etc. Bridge: a telecommunications network connection device that allows two local area networks to interconnect

Devices that handle the physical layer

Network Interface Card (NIC): LAN card, uniquely identifyingMac addresses reside here. Repeater: Amplifies an incoming signal and forwards it to the other end. AP: a device that copies packets; connects a wired LAN to a wireless network.