Fundamentals of Azure Internal Load balancers (ILBs)
Internal load balancing (ILB) enables you to run highly available services behind a private IP address
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
I am able to access internal load balancer using IP address but not via load balancer or service name?
- See Accessing the ILB below
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
How do I monitor the traffic and which server it is redirecting it to?
How do I setup the probing and rules/alerts for it?
- See the links below
ILB ENABLES THE FOLLOWING NEW TYPES OF LOAD BALANCING:
Between virtual machines within a cloud service.
Between virtual machines in different cloud services that are themselves contained within a virtual network.
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.
ILB CAN PERFORM LOAD BALANCING FOR TRAFFIC FROM INTRANET CLIENTS
Traffic from clients on the on-premises network get load-balanced across the set of LOB servers running in a cross-premises virtual network
You don't need a separate load balancer in the on-premises network or in the virtual network
Figure 2: Architecture for an Intranet Network
LOAD BALANCING ON-PREMISES SERVER TRAFFIC
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.
Figure 3: Architecture for an On-Premises Network
FROM ON PREMISES
- 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
VMs inside a cloud service have private IP address spaces
You can talk to the ILB using this private IP address
FROM WITHIN A VIRTUAL NETWORK
A customer can specify a static VNet IP address
A customer can retrieve the load balanced IP is acquired from a virtual subnet
This allows you to be connected VNets through the secure IP Sec tunnel
Some useful links
Regional Virtual Networks | https://azure.microsoft.com/blog/2014/05/14/regional-virtual-networks/# |
Internal Load Balancing | https://azure.microsoft.com/blog/2014/05/20/internal-load-balancing/# |
Configure an internal load-balanced set | https://msdn.microsoft.com/en-us/library/azure/dn690125.aspx# |
Azure Load Balancer | https://msdn.microsoft.com/en-us/library/azure/dn655058.aspx# |
Configure a load-balanced set | https://msdn.microsoft.com/en-us/library/azure/dn655055.aspx# |
Comments
Anonymous
February 18, 2015
How do you get the internal load balancer status? i.e. which VMs are currently servicing requests?Anonymous
April 14, 2015
Same question as Ben here - how can we see the current status of the ILB, and which members are flagged as up/down? It would also be useful to see history here, to identify for example whether a particular member has been flapping.Anonymous
September 18, 2015
The comment has been removed