AzS-SLB01

SLB01 is the VM responsible for all load balancing. With the former product, Azure Pack, there was no real load balancer available as Windows load balancing always had its issues with network devices at the tenant side. Therefore, the only solution for this was adding a third-party load balancer.

With Microsoft Azure, a software load balancer was always present, and SLB01 is again the same one running in public Azure. It has just been moved to Azure Stack. It is responsible for tenant load balancing but also provides high availability for Azure Stack infrastructure services. As expected, providing the SLB to Azure Stack cloud instances means deploying the corresponding ARM template. The underlying technology is load balancing based on hashes. By default, a 5-tuple hash is used, and it contains the following:

• Source IP
• Source port
• Destination IP
• Destination port
• Protocol type

The stickiness is only provided within one transport session, and packages of TCP or UDP sessions will always be transferred to the same instance beyond the load balancer. The following chart shows an overview of the hash-based traffic's contribution: