Download Load Balancer
Avice Michonski
Load balancers are used to provide availability and scalability to the application. The application can scale beyond the capacity of a single server. The load balancer works to steer the traffic to a pool of available servers through various load balancing algorithms. If more resources are needed, additional servers can be added.
Load balancers health check the application on the server to determine its availability. If the health check fails, the load balancer takes that instance of the application out of its pool of available servers. When the application comes back online, the health check validates its availability and the server is put back into the availability pool.
Because the load balancer is sitting in between the client and application server and managing the connection, it has the ability to perform other functions. The load balancer can perform content switching, provide content-based security like web application firewalls (WAF), and authentication enhancements like two factor authentication (2FA).
Load balancing is designed to give the application availability, scalability, and security. As a reverse-proxy, the load balancer acts as a multi-functional valve to direct and control the traffic between the clients and servers.
A load balancer is a reverse proxy. It presents a virtual IP address (VIP) representing the application to the client. The client connects to the VIP and the load balancer makes a determination through its algorithms to send the connection to a specific application instance on a server. The load balancer continues to manage and monitor the connection for the entire duration.
This is the primary function of the load balancer, server load balancing (SLB). The agent can provide additional functionality based on their role in the conversation. They can decide to allow and/or deny certain details (security). They may want to validate that the person they are talking to is actually the athlete in question (authentication). If the current sports league is not working out, the agent can send the discussions to a different league based on availability or location (GSLB).
As technology evolved, so did the load balancers. They became more advanced and started providing content awareness and content switching. These load balancers looked beyond the packet header and into the content payload. These load balancers look at the content such as the URL, HTTP header, and other things to make load balancing decisions. These are the application load balancers or Layer 7 load balancers.
Global server load balancing (GSLB) is actually a different technology than the traditional layer 4-7 load balancer. GSLB is based on DNS and acts as a DNS proxy to provide responses based on GSLB load balancing algorithms in real time. It is easiest to think of GSLB as a dynamic DNS technology that manages and monitors the multiple sites through configurations and health checks. Most load balancing solutions today offer GSLB as a component of their functionality.
Load balancers originated as hardware solutions. Hardware provides a simple appliance that delivers the functionality with a focus of performance. Hardware-based load balancers are designed for installation within datacenters. They are turn-key solutions that do not require the dependencies that software-based solutions require such as hypervisors and COTS hardware.
As network technologies evolved, software-defined, virtualization, and cloud technologies have become important. Software-based load balancing solutions offer flexibility and the ability to integrate into the virtualization orchestration solutions. Some environments such as cloud require software solutions. Software-based environments often use DevOps and/or CI/CD processes. The software load balancer is more suited for these environments with their flexibility and integration.
Elastic Load Balancer (ELB) solutions are far more sophisticated and offer cloud-computing operators scalable capacity based on traffic requirements at any one time. Elastic Load Balancing scales traffic to an application as demand changes over time. It also scales load balancing instances automatically and on-demand. As elastic load balancing uses request routing algorithms to distribute incoming application traffic across multiple instances or scale them as necessary, it increases the fault tolerance of your applications.
The Kemp LoadMaster load balancer is designed to optimize the load balancing experience. LoadMaster is a software-based solution that is also available as a hardware appliance. Kemp focuses on the core load balancing technologies to ensure a simplified configuration and management process. This focus translates to a significant TCO savings for the life of the technology.
Kemp offers world class support through an extensive organization of experts to offer assistance to customers 24x7. Kemp has built a team of load balancing and networking experts over many years to become a premier technology organization with over 100,000 deployments in 138 countries.
We host our ASP.NET applications on two web servers (Server 2003, IIS 6) that reside behind a hardware load balancer. When I look at the IIS logs, the c-ip value in the IIS (v6) logs are ALWAYS the IP address of the load balancer. I noticed in the http headers, there is an X-Forwarded-For header that appears to have the requesting IP address. Is there something I can do to make IIS log this header value in the logs?
When going through a proxy you the x-forwarded-for is what is most commonly used by load balancers. You can probably write an httpfilter which will swap this around yourself; or IIS Tracer has the ability to play with the standard files; including swapping the c-ip and x-forwarded field.
I am guessing it's a load balanced vserver from within Traffic Management > Load Balancing > Virtual Server with UDP protocol for both User Tunnel and Device Tunnel, 500 & 4500 but there are some pieces I am not sure about.. Persistence is one.. Assuming those tunnels are required to hit the same Service Group Member i.e. the RRAS server for x period of time or there would be inconsitencies in the VPN and it would probably bomb out..
The piece which doesn't seem to work well is if there are multiple clients sitting behind a NAT with single Public IP then they don't seem to get load balanced correctly. (port following in other vendors like Kemp LB seem to be able to handle this but not NS - but that might not be an issue for you. Going back to SSTP and Load balancing just 443 would be much easier in my mind with Netscalers.
So it looks like the LB controller which is in the kube-system namespace does not have permission to read the secret which is in the camp-ui namespace (the namespace of my application and ALB Ingress). I found the following post which I assume will solve this: -sigs.github.io/aws-load-balancer-controller/v2.4/examples/secrets_access/
To be more precise, the ingress will route to a service (that probably is type cluster IP), then the ingress routes traffic to that IP and kube-proxy does the load balancing. So, answering your question, nginx ingress is not acting so much as a load balancer, but it does that job in conjunction with kube-proxy.
CloudHub dedicated load balancers (DLBs) are an optional component of Anypoint Platform that enable you to route external HTTP and HTTPS traffic to multiple Mule applications deployed to CloudHub workers in a Virtual Private Cloud (VPC).
To use a dedicated load balancer in your environment, you must first create an Anypoint VPC. Because you can associate multiple environments with the same Anypoint VPC, you can use the same dedicated load balancer for your different environments.
Each DLB unit that you purchase is the equivalent of two workers handling load balancing between CloudHub workers.You can assign up to four load balancer units to a DLB.A DLB with four load balancer units assigned has eight workers.
To avoid connection issues when the load balancer is restarting, adhere to the DNS TTL (30 seconds), including connection keep alive. The connections are closed after the new workers are online and the TTL expires.
DLB uses DNS-based routing to distribute traffic across DLB workers and returns the IP address of all DLB workers to the calling client. A single DLB worker might receive all the client traffic within the TTL window regardless of the amount of transactions per second. To avoid this, ensure that you have granular load distribution between the DLB workers by alternating between the IP addresses returned in the DNS resolution.
Highly demanding enterprise networks require full-featured application delivery controller that optimizes application load balancing and performance while providing protection from an ever-expanding list of intrusions and attacks. The Barracuda Load Balancer ADC is a Secure Application Delivery Controller that enables Application Availability, Acceleration and Control, while providing Application Security Capabilities.
Available in hardware, virtual and cloud instances, the Barracuda Load Balancer ADC provides advanced Layer 4 and Layer 7 load balancing with SSL Offloading and Application Acceleration. The built-in Global Server Load Balancing (GSLB) module allows you to deploy your applications across multiple geo-dispersed locations. The Application Security module ensures comprehensive web application protection, including against OWASP Top 10 and Application DDoS attacks, while monitoring outbound traffic for Data Loss Prevention.
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