CB-Net

This article is a natural progression of the recent serieis of articles I have published on deployment and configuration of NetScaler VPX devices for load balancing Exchange 2010:

• • NetScaler : Load Balancing Exchange 2010
  • NetScaler : Configuring High Availability

 

What are VMACs are why use them?

VMAC’s are a useful addition in the NetScaler high availability tool set. In brief a VMAC creates a virtual MAC address that can ‘failover’ between devices. VMACs can be used to compliment the built-in HA or to create an active/active NetScaler pair.

By virtualising the MAC address there is no drop in network connectivity during failovers as the MAC address is shared across NetScaler devices – this means that the CAM table in the upstream switches does not require any update. As a result, failovers between NetScaler devices should be faster and less intrusive with regards to user sessions/connections.

VMAC’s work using a ‘priority’ – the higher priority determines ownership of the VMAC between devices. In a NetScaler HA configuration the priority of the VMAC between devices is the same, without HA it is configurable. For example if we had two NetScalers not using HA, NS1 and NS2, and a single VMAC configured on each we could set NS1 to have a priority of 100 and NS2 to have a priority of 90. NS1 would have ‘ownership’ of the VMAC because of its higher priority.

There are a couple of options when configuring VMAC’s:

1. If you are using the built-in NetScaler HA then you will continue to get Active/Passive HA
2. If you chose not to use the built-in HA feature then you can get Active/Active HA

One key benefit of using HA as well is that it synchronises the session tables across devices, without HA a failover of VMACs will disconnect Outlook Web Access users as their sessions is lost at failover, with HA sessions are kept, there is just a brief interruption to the user before they can carry on.

It is also possible to assign a VMAC to a single IP address, or group multiple IP addresses into a single VMAC. The first option allows for granularity when assigning ownership as you can assign each VMAC to a device of your choice whereas grouping the IP’s into a single VMAC reduces configuration but also reduces the options you have for splitting traffic. One option could be to group the IP’s into VMACs that represent services, so if you are load balancing multiple services via your NetScalers create a VMAC per service, i.e. Exchange 2010, Citrix Access Gateway etc.

In a NetScaler Load Balancing Exchange 2010 I covered deployment of a NetScaler device to Load Balance Exchange 2010, this is an extension fo that article – illustrating how to configure a second NetScaler device in a High Availability Pair.

In this article I’ll illustrate how to add a secondary NetScaler device and configure High Availability to ensure you have a resiliant NetScaler deployment.

This article will illustrate configuration of both a one-arm and two-arm topology for load balancing Exchange 2010 SP1 using a single NetScaler VPX (NS9.3: Build 52.3.nc). The specific focus is on a one-arm topology, however I’ll clearly outline what’s required if you decide to use a two-arm configuration; either way by the end of the article you’ll have a working deployment… I hope!

This guide assumes you have deployed the NetScaler VPX and configured an IP address – for information on how to do this see the NetScaler Deployment Article.

Deploying the Virtual Machine

First you’ll need to convert the OVF available for ESX using the OVF tool available here. Once installed, extract the NetScaler archiveand run the following command – changing the paths appropriately:

{code lang:css showtitle:false lines:false hidden:false}C:\Program Files\VMware\VMware OVF Tool\ovftool.exe “X:\NSVPX-ESX-9.3-52.3_nc\NSVPX-ESX-9.3-52.3_nc Folder\NSVPX-ESX-9.3-52.3_nc.ovf” “X:\NSVPX-ESX-9.3-52.3_nc\NSVPX-ESX-9.3-52.3_nc Folder\NSVPX.vmx”{/code}

The machine must have 2 vCPU’s and 2GB RAM in order to boot, so dont think about changing these as I did!

You’ll need to make one change in the VM settings; the Operating System – change this to Solaris 10 64-bit:

 Power on the VM, you’ll then be prompted to configure IPv4 addressing:

When finished you’ll be able to use a browser to navigate to the NetScaler Web Interface, after login you may be prompted to install JRE 6 update 14.

 

The default username and password are nsroot / nsroot

Initial Setup Wizard

When you login for the first time you’ll be prompted with the setup wizard, click next to proceed:

Confirm TCP/IPv4 settings for the NetScaler and also define the Mapped IP (MIP) Address – this is the address that client connections will appear to come from on your load balanced servers that utilise the NetScaler;

Choose to skip any configuration on the next page if you are using NetScaler for Exchange 2010, your configuration may vary here:

 

Click finish on the summary screen to apply the configuration:

 

Close any other windows that popup following this wizard. 

Obtain License From Citrix

Next things next you’ll need ot obtain a license from Citrix for the NetScaler;

1. Go to MyCitrix and create a new account, or login using your existing MyCitrix credentials.
2. After login, go to: My tools > Choose a Toolbox > Manage Licenses > Allocate.
3. Select the Don’t see your product? Link located at the top right corner of the Allocate web key page.
4. Enter the license code(s) displayed above in the Find your license dialog box and click Continue. 
5. When the Host Name warning page displays, select Continue. The hostname can be obtained using the following commands form the console:

{code lang:css showtitle:false lines:false hidden:false}shell{/code}

{code lang:css showtitle:false lines:false hidden:false}lmutil lmhostid –ether{/code}

(NOTE; remove the colon’s from the MAC address when inputting it into My Citrix!)

 Installing the License

In order to utilise most of the NetScaler functions you need to import your license that you downloaded in the last step.

Browse to System > Licenses from the NetScaler Management Interface

At the bottom of the page there is a ‘Manage Licenses…’ link, click it, click Add and browse to the file you downloaded:

Finally, click ‘OK’ – you’ll be prompted to reboot, after-which your NetScaler is ready for configuration.