Fundamentals of Azure Internal Load balancers ILBs

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Fundamentals of Azure Internal Load balancers by Bruno Terkaly 

  1. Internal load balancing (ILB) enables you to run highly available services behind a private IP address
  2. Internal load balancers are only accessible only within a cloud service or Virtual Network (VNet)
    • This provides additional security on that endpoint.

Some questions I am hearing

  1. I am able to access internal load balancer using IP address but not via load balancer or service name?
    • See Accessing the ILB below
  2. Is there any option on Azure portal to view load balancer configuration?
    • Internal load balancing cannot be configured through the portal as of today, this will be supported in the future
    • However, it can be configured using powershell cmdlets.
      • ILB can be used in a deployment inside a Regional Virtual Network as well in a new deployment that is outside the Virtual Network
  3. How do I monitor the traffic and which server it is redirecting it to?
  4. How do I setup the probing and rules/alerts for it?
    • See the links below

ILB ENABLES THE FOLLOWING NEW TYPES OF LOAD BALANCING:

  1. Between virtual machines within a cloud service.
  2. Between virtual machines in different cloud services that are themselves contained within a virtual network.
  3. Between on-premises computers and virtual machines in a cross-premises virtual network.

Some diagrams

EXAMPLE OF A MULTI-TIER APPLICATION USING WEB SERVERS AS THE FRONT END AND DATABASE SERVERS AS THE BACK END IN A CLOUD SERVICE.

  1. Multi-Tier Web Appimage001

    Figure 1: Architecture for a Multi-Tier Web App

ILB CAN PERFORM LOAD BALANCING FOR TRAFFIC FROM INTRANET CLIENTS

  1. Traffic from clients on the on-premises network get load-balanced across the set of LOB servers running in a cross-premises virtual network
  2. You don’t need a separate load balancer in the on-premises network or in the virtual networkimage002

    Figure 2: Architecture for an Intranet Network

LOAD BALANCING ON-PREMISES SERVER TRAFFIC

  1. ILB also allows traffic from servers on the on-premises network to be load-balanced across virtual machines running in a cross-premises virtual network.image003

    Figure 3: Architecture for an On-Premises Network

FROM ON PREMISES

  1. When used within a Virtual Network the ILB endpoint is also accessible from on-premises and other inter-connected VNets allowing some powerful hybrid scenarios

ACCESSING THE ILB

FROM INSIDE A CLOUD SERVICE

  1. VMs inside a cloud service have private IP address spaces
  2. You can talk to the ILB using this private IP address

FROM WITHIN A VIRTUAL NETWORK

  1. A customer can specify a static VNet IP address
  2. A customer can retrieve the load balanced IP is acquired from a virtual subnet
  3. This allows you to be connected VNets through the secure IP Sec tunnel

Some useful links

Regional Virtual Networks http://azure.microsoft.com/blog/2014/05/14/regional-virtual-networks/#
Internal Load Balancing http://azure.microsoft.com/blog/2014/05/20/internal-load-balancing/#
Configure an internal load-balanced set http://msdn.microsoft.com/en-us/library/azure/dn690125.aspx#
Azure Load Balancer http://msdn.microsoft.com/en-us/library/azure/dn655058.aspx#
Configure a load-balanced set http://msdn.microsoft.com/en-us/library/azure/dn655055.aspx#

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