Multiple DirectAccess servers can be deployed in a load-balanced cluster to eliminate single crucial points of failure and to provide scalability for the remote access solution. Load balancing can be enabled using the integrated Windows Network Load Balancing (NLB) or an external physical or virtual load balancer.
NLB Drawbacks and Limitations
NLB is often deployed because it is simple and inexpensive. However, NLB suffers from some serious drawbacks that limit its effectiveness in all but the smallest deployments. For example, NLB uses network broadcasts to communicate cluster heartbeat information. Each node in the cluster sends out a heartbeat message every second, which generates a lot of additional network traffic on the link and reduces performance as more nodes are added. Scalability is limited with NLB too, as only 8 nodes are supported, although the practical limit is 4 nodes. Further, NLB supports only round-robin connection distribution.
External Load Balancer
A better alternative is to implement a dedicated physical or virtual load balancing appliance. A purpose-built load balancer provides additional security, greater scalability (up to 32 nodes per cluster), improved performance, and fine-grained traffic control.
Migrate from NLB to ELB
It is possible to migrate to an external load balancer (ELB) after NLB has already been configured. To do this, follow the guidance provided in my latest blog post on the KEMP Technologies blog entitled “Migrating DirectAccess from NLB to KEMP LoadMaster Load Balancers”.
DirectAccess Deployment Guide for KEMP LoadMaster Load Balancers
Migrating DirectAccess from NLB to KEMP LoadMaster Load Balancers
Load Balancing DirectAccess with KEMP LoadMaster Load Balancers
DirectAccess Load Balancing Tips and Tricks Webinar with KEMP Technologies
DirectAccess Single NIC Load Balancing with KEMP LoadMaster Load Balancer
Configuring the KEMP LoadMaster Load Balancer for DirectAccess NLS
Enable DirectAccess Load Balancing Video
Implementing DirectAccess with Windows Server 2016 Book
Posted by Richard M. Hicks on November 17, 2016
Enabling load balancing for DirectAccess deployments is crucial for eliminating single points of failure and ensuring the highest levels of availability for the remote access solution. In addition, enabling load balancing allows DirectAccess administrators to quickly and efficiently add capacity in the event more processing power is required.
DirectAccess includes support for load balancing using integrated Windows Network Load Balancing (NLB) and external load balancers (physical or virtual). External load balancers are the recommended choice as they provide superior throughput, more granular traffic distribution, and greater visibility. External load balancers also more scalable, with support for much larger DirectAccess server clusters, up to 32 nodes. NLB is formally limited to 8 nodes, but because it operates at layer 2 in the OSI model and relies on broadcast heartbeat messages, it is effectively limited to 4 nodes.
The KEMP Technologies LoadMaster load balancer is an excellent choice for load balancing the DirectAccess workload. To learn more about configuring the LoadMaster with DirectAccess, join me for a free live webinar on Tuesday, August 16 at 10:00AM PDT where I’ll discuss DirectAccess load balancing in detail. I will also be sharing valuable tips, tricks, and best practices for load balancing DirectAccess.
Don’t miss out. Register today!
DirectAccess Load Balancing Overview
Load Balancing DirectAccess with the KEMP Loadmaster Load Balancer
Maximize your investment in Windows 10 with DirectAccess and the KEMP LoadMaster Load Balancer
KEMP LoadMaster DirectAccess Deployment Guide
Posted by Richard M. Hicks on August 9, 2016
Configuring load balancing in DirectAccess is essential for eliminating single points of failure and ensuring the highest level of availability for the solution. The process of enabling load balancing for DirectAccess can be confusing though, as it involves the reassignment of IP addresses from the first server to the virtual IP address (VIP) for the cluster.
In this video I demonstrate how to enable DirectAccess load balancing and explain in detail how IP address assignment works for both Network Load Balancing (NLB) and external load balancers (ELB).
Posted by Richard M. Hicks on June 21, 2016