Always On VPN Multisite with Azure Traffic Manager

Always On VPN Multisite with Azure Traffic ManagerEliminating single points of failure is crucial to ensuring the highest levels of availability for any remote access solution. For Windows 10 Always On VPN deployments, the Windows Server 2016 Routing and Remote Access Service (RRAS) and Network Policy Server (NPS) servers can be load balanced to provide redundancy and high availability within a single datacenter. Additional RRAS and NPS servers can be deployed in another datacenter or in Azure to provide geographic redundancy if one datacenter is unavailable, or to provide access to VPN servers based on the location of the client.

Multisite Always On VPN

Unlike DirectAccess, Windows 10 Always On VPN does not natively include support for multisite. However, enabling multisite geographic redundancy can be implemented using Azure Traffic Manager.

Azure Traffic Manager

Traffic Manager is part of Microsoft’s Azure public cloud solution. It provides Global Server Load Balancing (GSLB) functionality by resolving DNS queries for the VPN public hostname to an IP address of the most optimal VPN server.

Advantages and Disadvantages

Using Azure Traffic manager has some benefits, but it is not with some drawbacks.

Advantages – Azure Traffic Manager is easy to configure and use. It requires no proprietary hardware to procure, manage, and support.

Disadvantages – Azure Traffic Manager offers only limited health check options. Azure Traffic Manager’s HTTPS health check only accepts HTTP 200 OK responses as valid. Most TLS-based VPNs will respond with an HTTP 401 Unauthorized, which Azure Traffic Manager considers “degraded”. The only option for endpoint monitoring is a simple TCP connection to port 443, which is a less accurate indicator of endpoint availability.

Note: This scenario assumes that RRAS with Secure Socket Tunneling Protocol (SSTP) or another third-party TLS-based VPN server is in use. If IKEv2 is to be supported exclusively, it will still be necessary to publish an HTTP or HTTPS-based service for Azure Traffic Manager to monitor site availability.

Traffic Routing Methods

Azure Traffic Manager provide four different methods for routing traffic.

Priority – Select this option to provide active/passive failover. A primary VPN server is defined to which all traffic is routed. If the primary server is unavailable, traffic will be routed to another backup server.

Weighted – Select this option to provide active/active failover. Traffic is routed to all VPN servers equally, or unequally if desired. The administrator defines the percentage of traffic routed to each server.

Performance – Select this option to route traffic to the VPN server with the lowest latency. This ensures VPN clients connect to the server that responds the quickest.

Geographic – Select this option to route traffic to a VPN server based on the VPN client’s physical location.

Configure Azure Traffic Manager

Open the Azure management portal and follow the steps below to configure Azure Traffic Manager for multisite Windows 10 Always On VPN.

Create a Traffic Manager Resource

  1. Click Create a resource.
  2. Click Networking.
  3. Click Traffic Manager profile.

Create a Traffic Manager Profile

  1. Enter a unique name for the Traffic Manager profile.
  2. Select an appropriate routing method (described above).
  3. Select a subscription.
  4. Create or select a resource group.
  5. Select a resource group location.
  6. Click Create.

Always On VPN Multisite with Azure Traffic Manager

Important Note: The name of the Traffic Manager profile cannot be used by VPN clients to connect to the VPN server, since a TLS certificate cannot be obtained for the trafficmanager.net domain. Instead, create a CNAME DNS record that points to the Traffic Manager FQDN and ensure that name matches the subject or a Subject Alternative Name (SAN) entry on the VPN server’s TLS and/or IKEv2 certificates.

Endpoint Monitoring

Open the newly created Traffic Manager profile and perform the following tasks to enable endpoint monitoring.

  1. Click Configuration.
  2. Select TCP from the Protocol drop-down list.
  3. Enter 443 in the Port field.
  4. Update any additional settings, such as DNS TTL, probing interval, tolerated number of failures, and probe timeout, as required.
  5. Click Save.

Always On VPN Multisite with Azure Traffic Manager

Endpoint Configuration

Follow the steps below to add VPN endpoints to the Traffic Manager profile.

  1. Click Endpoints.
  2. Click Add.
  3. Select External Endpoint from the Type drop-down list.
  4. Enter a descriptive name for the endpoint.
  5. Enter the Fully Qualified Domain Name (FQDN) or the IP address of the first VPN server.
  6. Select a geography from the Location drop-down list.
  7. Click OK.
  8. Repeat the steps above for any additional datacenters where VPN servers are deployed.

Always On VPN Multisite with Azure Traffic Manager

Summary

Implementing multisite by placing VPN servers is multiple physical locations will ensure that VPN connections can be established successfully even when an entire datacenter is offline. In addition, active/active scenarios can be implemented, where VPN client connections can be routed to the most optimal datacenter based on a variety of parameters, including current server load or the client’s current location.

Additional Information

Windows 10 Always On VPN Hands-On Training Classes

Windows 10 Multisite DirectAccess with GSLB Webinar

Kemp Technologies LoadMaster Load BalancerWindows 10 clients include full support for all enterprise DirectAccess scalability and redundancy features, including automatic site selection and transparent failover for multisite deployments. However, the native site selection process is limited in functionality and often yields unexpected results.

To provide better client support for multisite DirectAccess, a Global Server Load Balancer (GSLB) solution such as the Kemp Technologies LoadMaster GEO can be deployed. Using the LoadMaster’s GSLB functionality can significantly enhance multisite site selection for Windows 10 clients. In addition, it can be used to enable new scenarios not supported natively such as weighted distribution and active/passive failover.

Kemp Technologies LoadMaster Load Balancer

To learn more about how address the shortcomings of DirectAccess multisite using the Kemp LoadMaster GEO, join me for a live webinar on Thursday, July 14, 2106 at 10:00AM EDT where I’ll discuss the following topics.

  • How Global Server Load Balancing (GSLB) works
  • How Windows 10 clients choose an entry point
  • Understand the limitations of the native site selection process for Windows 10 clients
  • How to use the Kemp LoadMaster GEO to provide true geographic redundancy
  • How to enable active/passive failover for disaster recovery

You can register for this free live webinar here.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Introduction

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic ManagerTo provide geographic redundancy, DirectAccess can be deployed in a multisite configuration. In this scenario, Windows 8.x and Windows 10 clients are aware of all entry points in the enterprise and will automatically select the nearest available entry point to connect to. The nearest entry point is defined as the one that responds the quickest. When a Windows 8.x or Windows 10 client attempts to establish DirectAccess connectivity, an HTTP GET is sent to all entry points and the client will select the one with the shortest Round Trip Time (RTT) for the request.

Note: Windows 7 clients can be provisioned when DirectAccess is configured for multisite access, but they must be assigned to an individual entry point.

Challenges

There are a number of challenges that come with the default multisite configuration. Choosing an entry point based solely on network latency is rather simplistic and can often produce unexpected results. It also lacks support for granular traffic distribution or active/passive configuration.

GSLB

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic ManagerFor the best experience, DirectAccess can be configured to use a Global Server Load Balancing (GSLB) solution to enhance transparent site selection and failover for Windows 8.x and Windows 10 clients. Commonly this is implemented using an on-premises appliance (Citrix NetScaler, F5 Global Traffic Manager, Kemp LoadMaster, A10 Thunder, etc.). These solutions offer exceptional control over DirectAccess traffic distribution, but they add expense and complexity.

Azure Traffic Manager

Azure Traffic Manager is a cloud-based GSLB solution that is a simple and cost-effective alternative to dedicated on-premises appliances. While it does not offer all of the features that GSLB appliances provide, it does provide better traffic distribution options than the default configuration. Importantly, it enables active/passive failover, which is a common requirement not supported natively with DirectAccess.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Traffic Manager Configuration

In the Azure portal (the new one, not the old one!) click New, Networking, and then Traffic Manager profile.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Provide a name and select a Routing method.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Routing method options are Performance, Weighted and Priority.

  • Performance. Select this option to enable clients to connect to the entry point with the lowest network latency.
  • Weighted. Select this option to enable clients to prefer some entry points more than others. Assign a weight value of 1 to 1000 for each entry point. Higher values have more preference. Values for entry points can be the same, if desired.
  • Priority. Select this option to enable clients to connect to a primary entry point, then fail over to a secondary or tertiary entry point in the event of an outage. Assign a priority value of 1 to 1000 for each entry point. Lower values take precedence. Each entry point must be assigned a unique priority value.

Click Create when finished. Next click Settings for the new traffic manager profile and click Configuration. Change Protocol to HTTPS, Port to 443, and Path to /IPHTTPS. Click Save when finished.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Next click Endpoints and click Add. Select External endpoint from the drop down list, provide a descriptive name, and then enter the Fully-Qualified Domain Name (FQDN) of the first DirectAccess entry point. When using the Performance routing method, choose a location that best represents the geography where the DirectAccess entry point is located. When using the Weighted or Priority routing methods, specify an appropriate value accordingly. Click Ok when finished. Repeat these steps for each entry point in the organization.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

DirectAccess Configuration

In the Remote Access Management console, highlight DirectAccess and VPN below Configuration in the navigation tree and then click Configure Multisite Settings below Multisite Deployment in the Tasks pane. Click Global Load Balancing and choose Yes, use global load balancing. Enter the FQDN of the Azure Traffic Manager profile and click Next, and then click Commit.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Note: An SSL certificate with a subject name matching that of the GSLB FQDN is not required.

In some cases, the management console may report that global load balancing addresses cannot be identified automatically for some or all entry points.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

If this occurs, it will be necessary to run the Set-DAEntryPoint PowerShell cmdlet to assign GLSB IP addresses to each entry point. The GSLB IP address is the public IPv4 address that the entry point public hostname resolves to.

Set-DAEntryPoint -Name [entrypoint_name] -GslbIP [external_ip_address]

For example:

Set-DAEntryPoint -Name "US West" -GslbIP 203.0.113.195
Set-DAEntryPoint -Name "US East" -GslbIP 198.51.100.21

Summary

DirectAccess includes native functionality to enable geographic load balancing for Windows 8.x and Windows 10 clients. The site selection process used by DirectAccess clients in this scenario is basic, and has the potential to yield unexpected results. Azure Traffic Manager is a simple, cost-effective alternative to dedicated on-premises GSLB appliances. It can be integrated with DirectAccess to address some of the shortcomings with the native entry point selection process.

Additional Resources

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