Review of the Kemp Technologies Loadmaster VLM-1000…

by Andy Grogan on June 5, 2012 · 2 comments

in Exchange 2010 (Admin), Exchange 2010 (General), Loadbalancing, Product Reviews

Copyright 2012 Kemp TechnologiesI don’t normally do reviews on the blog, but I was recently approached by a partner of Kemp Technologies enquiring if I would be willing to have a look at the Kemp Loadmaster VLM-1000 and offer my thoughts of the product to my readers.

I had a think about it, and decided that it was worth doing as I had heard great things about Kemp’s line of load balancers (there are a few members of the MVP community who swear by them (not at them, by them)) therefore I was very interested to see if they were as good as I had been led to believe.

NOTE: To be completely upfront with my readers – as part of this review I was given a full, unlimited NFR (not for resale) copy of Kemp’s VLM Software. I will not be using this in production, nor will any organisation that I work for benefit from being given a copy of this product. Aside from the NFR license I have not received any form of payment for conducting the review.

Like many folks who work with Exchange, I have encountered my own fair share of load balancing scenarios (ranging from using Windows own NLB, Round Robin, strange stuff with routers, to other Load Balancing products from vendors such as F5 or Loadbalancer).

The VLM-1000 itself is a virtual image (either Hyper-V or VMWare) of the native physical Kemp Appliance on the Loadmaster O/S – which performs L4 (Layer) load balancing and L7 content switching, SSL offloading, caching, compression, application health check and a lot more besides – see the table below:

Model Number



Price* (1st year support included)

£ 1,180 (RRP)

£ 3,150 (RRP)

Max Balancer Throughput


Unrestricted 1

SSL Transactions Per/Second (TPS)


249 1

Requests per second (HTTP)

31,883 1

31,883 1

Layer 4 concurrent connections

2,000,000 1

2,000,000 1

Max Servers Supported / Virtual Clusters



Layer 4/7 Load Balancing



Content Switching



Caching, Compression Engine



IPS (SNORT-Rules compatible)



MS Exchange 2010 Optimized



L7 Support for MS Terminal Services



Active/Hot-standby Redundant Operation



Bonding/Teaming Ports (802.3ad/LACP)



VLAN Trunking (802.1Q)



The software weighs in at a nice and compact 40MB download from the Kemp site, which immediately gave me a positive impression that this was obviously a well designed product.

Lab Configuration Used

For the purposes of the review I have decided to use a single arm (or one arm) Load Balancing configuration. A one arm configuration means that the Virtual Servers (or Services or VIP) that are published via the Load Balancer are in the same sub-net as the “Real Servers” – e.g. Exchange Client Access Servers.

The Load Balancer connects at Layer 2 through eth0 (which is the default interface of the the Kemp VM) – and VIPS are published through this interface as unique IP addresses (in a two arm scenario eth1 would typically connect to a different subnet).

As a conceptual overview – my Lab includes the Kemp VLM, three Exchange Mailbox Servers in a DAG – two of the servers have the Client Access role installed. There is a Client Access Array within my environment which is configured to point at VIP-2 via DNS. OWA Access is handled via VIP-1 – see below:



Installation of VLM-1000

Initial setup as you might expect for a Hyper-V image was very straight forward and was accomplished by opening the Hyper-V Server Manager – right clicking on my Hyper-V instance then selecting the “Import Virtual Machine” option from the context menu which appears.

This opens the “Import Virtual Machine” dialog box – where you can browse to the folder where the extracted Hyper-V image is  – make sure that the “Copy the Virtual Machine” option is selected so that a new unique ID is created for the machine.

Hyper-V will then go aware and import the machine – see below:


When imported you will see that the LVM-1000 has been configured with two NIC interfaces, a default CPU type and 1GB of RAM:


Powering on the Virtual Machine instigates a very simple initial setup process, I recommend that you have DHCP operating within your environment as this will enable the VLM to pickup a temporary address – you can then connect via the web interface to license the product using an address which is within your normal subnet. Although this is not essential as the appliance picks up a default address during boot (192.168.x.x) if it does not get a DHCP assigned address from the Network.

For this review I used the Virtual Machine Console of the Virtual Machine to perform the initial setup by providing the following credentials at the logon prompt:

Username: bal

Password: 1fourall

Upon logon you are presented with the licensing dialog box – whereas getting you licensing is pretty straight forward you need to be mindful that keeping a backup of your configuration is essential – as the license key is unique to the Virtual Machine (which is understandable).

If you lose the key and need to rebuild for any reason – there will be a fair chance that you will need to request a new key for the device – see below:


The installation program will start it’s “Quick Setup” process which will ask for the following items of information

  • Primary eth0 IP address – this will be the address that you can connect to the web interface from:
  • Host Name
  • Name (DNS) Server(s) addresses
  • Search Domain List – these should be internal DNS namespaces and any other that are relevant to your configuration
  • Default Gateway

eth0 – IP Address:


Host Name:


DNS Server(s):


Search Domains:


Default Gateway:


When the above information has been provided, it should then be possible to connect to the web interface management URL which is located at https://[IP_Address_of_eth0/ – logging in will present you with the VLM management interface:


Configuring the VLM-1000

This has to be my favourite aspect of the virtual appliance, as the basic configuration is so darn simple! You have a couple of choices:

  1. If you are familiar with Load Balancing concepts and technologies you can use the Web Interface to define Virtual Services and Real Servers Manually within the interface
  2. If you are not confident with Load Balancing in regard to Exchange – Kemp provide a number of common Exchange configuration templates for Download which can be imported into the Virtual Appliance which pre-configure certain settings for OWA, MAPI, SMTP, Unified Comms, POP and IMAP – these can be downloaded from here:

They can then be imported into the VLM via [ Virtual Services –> Manage Templates from the web Interface ] – see below:


Configuring your VIPS is then very straightforward – you can assign Virtual Addresses to Services via [ Virtual Services –> Add New ] then provide an IP address and then from the “Use Template” option select one of the pre-defined configurations from the “Use Template” drop down – have used Exchange HTTPS – in my example below:


You can then go into the configuration of the Service from [ Virtual Services –> View / Modify Services ] choosing the service that you have configured and then expanding the “Real Servers” option and then clicking on the “Add New” button – see below:


I also found during my testing that setting the “Scheduling Method” on the VIP to “Least Connection” [ Virtual Services –> View / Modify Services –> <OWA Service Name > –> Standard Options ] worked better with OWA in my environment – see below:


You can repeat the above steps for other Exchange 2010 services, which I can really tell you saves a heck of a lot of time!

Overall Impressions and a Comparison

To be fair in this review I have only looked at the Kemp solution in isolation from other products – therefore I should compare it against a comparable vendor from the same market place. The closet product that I have encountered (that can be Virtualised) is’s Enterprise VA. I have not reviewed that product on this site (although I almost did some years ago – but regrettably did not get around to completing it ~ I am thinking that I perhaps need to revisit this).

From my own personal perspective – I found the initial configuration, management and setup of Kemp’s VLM a very straightforward and intuitive process, whereas when I was originally looking at Enterprise VA I did have to “fiddle” a little more to get VIP’s like MAPI access working properly so there is a bit of a difference from a usability point of view.

Looking at costs – at this moment in time Enterprise VA initially appears to pip Kemp’s VLM – but the support provision out of the box is somewhat different between the two vendors – see below:

  • Enterprise VA: RRP: £1995 (with 90 day technical support)
  • Kemp VLM-1000: RRP: £3150 (with 1 year support included)

My view of support is that it is essential for any software that you put within a resilient infrastructure – so the duration of, and level of support should be a key evaluator for any purchase that you make. Kemp provides you will a full 9 months more support out of the box over Enterprise VA – however there may be other similar solutions where the cover is better, the point it to make a choice based upon knowing the market and understanding what your support requirements might be.

The Kemp platform has more features than you can shake a long pointy stick at. Admittedly so do other platforms such as Enterprise VA. However, what differentiates the Kemp VLM is that the features are targeted at Exchange and are very simple to configure. I think that that the VLM-1000 platform wins hands down in terms of “bangs for buck” and allowing administrators of all skill levels to leverage those features.

From a performance perspective, it would appear from the marketing materials that Enterprise VA provide – EVA out performs Kemp’s offering in a number of areas. However you should be mindful that with Virtual Appliances – performance metrics are in the eye of the beholder to a certain extent – and will vary from environment to environment according to prevailing configuration conditions.

From my point of view I would surmise that the two solutions would probably perform comparably and therefore would be difficult to say that one is better than the other.

From a deployment perspective – I think that Kemp’s VLM offers the better level of flexibility as it is supplied in both VMWare and Hyper-V formats, whereas Enterprise VA is only available in VMWare format. Now one could argue that doesn’t preclude Enterprise VA from working within (or being ported to) a Hyper-V environment – but that is another level of complexity that the Kemp offering does not have.

Both Enterprise VA and Kemp’s VLM can be deployed in fault tolerant pairs – however I was not able to test this in my lab for either product and can only surmise that they both work as you would expect. Licensing HA with Enterprise VA appears to be very competitive (with a RRP of £2995 for n+1) – however Kemp offers a very creative and costs effective SPLA licensing programme for its software.

Cost is always going to be a determining factor when choosing any solution – therefore I would argue is that in the current economic climate organisations should consider the option of “renting solutions based upon demand” (e.g. SPLA).

Working within such arrangements moves away from financial concerns such as on-going CapEx, RevEx and co-term of contract (e.g. how long are you tied in for). By adopting an SPLA model can potentially give you more control of your investment.

Looking at both solutions from an Exchange admin perspective, I think that it would be fair to say that Kemp’s offering in VLM is more targeted at Exchange Server (whilst it can also load balance other services) – whereas Enterprise VA is more a multi-purpose device, this maybe a determining factor for some administrators looking to buy a LB product.

To finish, I would say that the Kemp VLM-1000 is a very good software based Load Balancer, with a rich feature set and is polished in terms of simplicity of configuration. It has a growing pedigree in the Exchange Server market and is being used and recommended by a number of leading Exchange experts, MVP’s, MCM’s and customers alike – so it is very much worth a look as it has many positive attributes.

I also know from asking a few people, that Kemp’s post sales support is very, very good and my gut is telling me that it is rapidly becoming the Loadbalancer of choice for Exchange Server (with good reason).

However, it is important to know that there are other products in the market which can “load balance” Exchange – Enterprise VA is one example that I have used as a comparative baseline (there are others) – so Kemp’s offering should be reviewed inline against those solutions, however I urge people to really look at the small print – as it might seem on face value that another product is cheaper and performs better than Kemp. But in reality I think that you will find that is probably not the case.


{ 1 comment… read it below or add one }

Malcolm Turnbull July 1, 2017 at 12:21 pm


Nice clean review, I agree Kemp is a great solution for Exchange and they seem to have cornered a large part of the market.
Could I encourage you to take another look at the appliance?
We have a slightly different approach to sales & support and I’d be very interested to hear your opinion.


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