FAQs

The following section helps you to categorize the FAQs based on Citrix Application Delivery Controller (ADC) VPX.

• Feature and functionality

• Encryption

• Pricing and packaging

• [Citrix ADC VPX Express] (#citrix-ADC-VPX-Express-and-90-day-free-trial)

• Hypervisor

• Capacity planning or sizing

• System requirements

• Other technical FAQs

Feature and functionality

What is Citrix ADC VPX?

Citrix ADC VPX is a virtual ADC appliance that can be hosted on a Hypervisor installed on industry standard servers.

Does Citrix ADC VPX include all the web application optimization functionality as ADC appliances?

Yes. Citrix ADC VPX includes all load balancing, traffic management, application acceleration, application security (including Citrix ADC Gateway and Citrix Application Firewall), and offload functionality. For a complete overview of the Citrix ADC feature and functionality, see Application delivery your way.

Are there any limitations with Citrix Application Firewall when using it on Citrix ADC VPX?

Citrix Application Firewall on Citrix ADC VPX provides the same security protections as it does on Citrix ADC appliances. Performance or throughput of Citrix Application Firewall varies by platform.

Are there any differences between Citrix ADC Gateway on Citrix ADC VPX and Citrix ADC Gateway on Citrix ADC appliances?

Functionally, they are identical. Citrix ADC Gateway on Citrix ADC VPX supports all the Citrix ADC Gateway features available in Citrix ADC software release 9.1. However, because Citrix ADC appliances provide dedicated SSL acceleration hardware, it offers greater SSL VPN scalability than a Citrix ADC VPX instance.

Other than the obvious difference of being able to run on a Hypervisor, how does Citrix ADC VPX differ from Citrix ADC physical appliances?

There are two main areas where customers see differences in behavior. The first is Citrix ADC VPX cannot offer the same performance as many Citrix ADC appliances. The second is that while Citrix ADC appliances incorporate its own L2 networking functionality, Citrix ADC VPX relies upon the Hypervisor for its L2 networking services. Generally, it does not limit how the Citrix ADC VPX can be deployed. There can be certain L2 functionality that is configured on a physical Citrix ADC appliance must be configured on the underlying Hypervisor.

How does Citrix ADC VPX play a role in the Application Delivery market?

Citrix ADC VPX changes the game in the application delivery market in the following ways:

• By making a Citrix ADC appliance even more affordable, Citrix ADC VPX enables any IT organization to deploy a Citrix ADC appliance. It is not just for their most mission-critical web applications, but for all of their Web applications.

• Citrix ADC VPX allows customers to further converge networking and virtualization within their data centers. Citrix ADC VPX cannot only be used to optimize web applications hosted on virtualized servers. It also enables web application delivery itself to become a virtualized service that can be easily and rapidly deployed anywhere. IT organizations use the standard data center processes for tasks such as provisioning, automation, and charge-back for the web application delivery infrastructure.

• Citrix ADC VPX opens up new deployment architectures that are not practical if only physical appliances are used. Citrix ADC VPX and Citrix ADC MPX appliances can be used basis, tailored to the individual needs of each respective application to handle processor-intensive actions such as compression and application firewall inspection. At the data center edge, Citrix ADC MPX appliances handle high-volume network-wide tasks such as initial traffic distribution, SSL encryption or decryption, denial of service (DoS) attack prevention, and global load balancing. Pairing high-performance Citrix ADC MPX appliances with easy-to-deploy Citrix ADC VPX virtual appliance brings unparalleled flexibility and customization capabilities to modern, large-scale, data center environments while also reducing overall data center costs.

How does Citrix ADC VPX fit into our Citrix delivery center strategy?

With the availability of Citrix ADC VPX, the entire Citrix delivery center offering is available as a virtualized offering. The entire Citrix delivery center benefits from the powerful management, provisioning, monitoring, and reporting capabilities available in Citrix XenCenter. This can be deployed rapidly into almost any environment, and managed centrally from anywhere. With one integrated, virtualized application delivery infrastructure, organizations can deliver desktops, client-server applications, and Web applications.

Encryption

Does Citrix ADC VPX support SSL offload?

Yes. However, Citrix ADC VPX does all SSL processing in software, so Citrix ADC VPX does not offer the same SSL performance as Citrix ADC appliances. Citrix ADC VPX can support up to 750 new SSL transactions per second.

Does third-party SSL cards installed on the server hosting Citrix ADC VPX accelerate SSL encryption or decryption?

No. Supporting third-party SSL cards cannot associate the Citrix ADC VPX to specific hardware implementations. It greatly diminishes an organizations ability to flexibly host Citrix ADC VPX anywhere within the data center. Citrix ADC MPX appliances must be used when more SSL throughput than Citrix ADC VPX provides is required.

Does Citrix ADC VPX support the same encryption ciphers as physical Citrix ADC appliances?

VPX supports all encryption ciphers as physical Citrix ADC appliances, except the ECDSA.

What is the SSL transactions throughput of Citrix ADC VPX?

See Citrix ADC VPX data sheet for information on SSL transactions throughput.

Pricing and packaging

How is Citrix ADC VPX packaged?

Citrix ADC VPX selection is similar to the selection of Citrix ADC appliances. First, the customer selects the Citrix ADC edition based on its functionality requirements. Then, the customer selects the specific Citrix ADC VPX bandwidth tier based on their throughput requirements. Citrix ADC VPX is available in Standard, Advanced, and Premium Editions. Citrix ADC VPX offers from 10 Mbps (VPX 10) to 100 Gbps (VPX 100G). More details can be found in the Citrix ADC VPX data sheet.

Is Citrix ADC VPX priced the same for all Hypervisors?

Yes.

Are the same Citrix ADC SKUs used for VPX on all Hypervisors?

Yes.

Can a Citrix ADC VPX license be moved from one Hypervisor to another (For example from VMware to Hyper-V)?

Yes. Citrix ADC VPX licenses are independent of the underlying Hypervisor. If you decide to move the Citrix ADC VPX virtual machine from one Hypervisor to another, you do not have to get a new license. However, you might need to rehost the existing Citrix ADC VPX license.

Can Citrix ADC VPX instances be upgraded?

Yes. Both the throughput limits and Citrix ADC family edition can be upgraded. Upgrade SKUs for both types of upgrade are available.

If I want to deploy Citrix ADC VPX in a high availability pair, how many licenses do I need?

As with Citrix ADC physical appliances, a Citrix ADC high availability configuration requires two active instances. Therefore, the customer must purchase two licenses.

Citrix ADC VPX Express and 90-day fee trial

Does Citrix ADC VPX Express include all Citrix ADC standard functionality? Does it include Citrix ADC Gateway and load balancing for Citrix Virtual Apps (formerly XenApp) Web Interface and XML broker?

Yes. Citrix ADC VPX Express includes full Citrix ADC Standard functionality. Starting from Citrix ADC release 12.0–56.20, Citrix modified the VPX express behavior.

Does Citrix ADC VPX Express include all Citrix ADC standard functionality? Does it include Citrix ADC Gateway and load balancing for Citrix Virtual Apps Web Interface and XML broker?

Starting from Citrix ADC release 12.0–56.20, VPX Express offers the Citrix ADC Standard Edition feature set, except Gateway functionality. Earlier to the 12.0–56.20 release, VPX expresses includes all features in the standard edition.

Does Citrix ADC VPX Express require a license?

With the new Citrix ADC VPX Express release (12.0–56.20 and onwards), VPX Express is free and requires no license files to install and comes with no commitment. If you have a VPX Express license already, then the prior VPX Express behavior is preserved. If the VPX Express license file is removed and the 12.0–56.20 and onwards release is used, the new VPX express behavior takes effect.

Does the Citrix ADC VPX Express license expire?

With the new VPX express, no. There is no license and no expiry date. If you have a VPX express license already, the license expires one year after download.

Does Citrix ADC VPX Express include the five free Citrix ADC Gateway concurrent licenses?

Yes, if you own a VPX express license.

Is there a limit to how many Citrix ADC VPX Expresses a customer can download?

Five.

Does Citrix ADC VPX Express support the same encryption ciphers as Citrix ADC MPX appliances?

For general availability, all the same strong encryption ciphers supported on Citrix ADC appliances are available on Citrix ADC VPX and Citrix ADC VPX Express. It is subjected to the same import or export regulations.

Can I file technical support cases for Citrix ADC VPX Express?

No. A retail Citrix ADC VPX license such as, VPX-10, VPX-200, VPX-1000, VPX- 3000 is required to file technical support cases. However, Citrix ADC VPX Express users are free to use both the Citrix ADC VPX Knowledge Center, and request help from the community using the Z discussion forums.

Can Citrix ADC VPX Express be upgraded to a retail version?

Yes. Simply purchase the retail Citrix ADC VPX license you need, and then apply the corresponding license to the Citrix ADC VPX Express instance.

Hypervisor

What VMware versions does Citrix ADC VPX support?

Citrix ADC VPX supports both VMware ESX and ESXi for versions 3.5 or later. For more information, see Support matrix and usage guidelines

For VMware, how many virtual network interfaces can you allocate to a VPX?

You can allocate up to 10 virtual network interfaces to a Citrix ADC VPX.

From vSphere, how can we access the Citrix ADC VPX command line?

The VMware vSphere client provides built-in access to the Citrix ADC VPX command line through a console tab. Also, you can use any SSH or Telnet client to access the command line. You can use the NSIP address of the Citrix ADC VPX in the SSH or Telnet client.

How can you access the Citrix ADC VPX GUI?

To access the Citrix ADC VPX GUI, type the NSIP of the Citrix ADC VPX, for example, http://NSIP address in the address field of any browser.

Can two Citrix ADC VPX instances installed on the same VMware ESX be configured in a high availability setup?

Yes, but it is not recommended. A hardware failure would affect both Citrix ADC VPX instances.

Can two Citrix ADC VPX instances running on two different VMware ESX systems be configured in a high availability setup?

Yes. It is recommended in a high availability setup.

For the VMware, are interface related events supported on Citrix ADC VPX?

No. Interface related events are not supported.

For the VMware, are tagged VLANs supported on Citrix ADC VPX?

Yes. Citrix ADC tagged VLANs are supported on Citrix ADC VPX from release 11.0 and higher. For more information, see Citrix documentation.

For VMware, are link aggregation and LACP supported on Citrix ADC VPX?

No. Link Aggregation and LACP are not supported for Citrix ADC VPX. Link aggregation must be configured at the VMware level.

How do we access Citrix ADC VPX documentation?

The documentation is available from the Citrix ADC VPX GUI. After logging in, select the Documentation tab.

Capacity planning or sizing

What performance can I expect with Citrix ADC VPX?

Citrix ADC VPX offers good performance. See Citrix ADC VPX data sheet for a specific performance level achievable using Citrix ADC VPX.

Given that server CPU power varies, how can we estimate the maximum performance of a Citrix ADC instance?

Using a faster CPU can result in higher performance (up to the maximum allowed by the license), while using a slower CPU can certainly limit the performance.

Are Citrix ADC VPX bandwidth or throughput limits for inbound only traffic, or both inbound and outbound traffic?

Citrix ADC VPX bandwidth limits are enforced for traffic inbound to the Citrix ADC only, regardless of whether the request traffic or response traffic. It indicates that a Citrix ADC VPX-1000 (for example) can process both 1 Gbps of inbound traffic and 1 Gbps of outbound traffic simultaneously. Inbound and outbound traffic is not the same as request and response traffic. To the Citrix ADC, both traffic coming from endpoints (request traffic) and traffic coming from origin servers (response traffic) is “inbound” (that is, coming into the Citrix ADC).

Can multiple instances of Citrix ADC VPX be run on the same server?

Yes. However, ensure that the physical server has enough CPU and I/O capacity to support the total workload running on the host, or Citrix ADC VPX performance can be impacted.

If more than one instance of Citrix ADC VPX is running on a physical server, what is the minimum hardware requirement per Citrix ADC VPX instance?

Each Citrix ADC VPX instance must be allocated 2 GB of physical RAM, 20 GB of hard disk space, and 2 vCPUs.

Note:

The Citrix ADC VPX is a latency-sensitive, high-performance virtual appliance. To deliver its expected performance, the appliance requires vCPU reservation, memory reservation, vCPU pinning on the host. Also, hyper threading must be disabled on the host. If the host does not meet these requirements, issues such as high-availability failover, CPU spike within the VPX instance, sluggishness in accessing the VPX CLI, pit boss daemon crash, packet drops, and low throughput occur.

Make sure that every VPX instance meets the predefined conditions.

Can I host Citrix ADC VPX and other applications on the same server?

Yes. For example, Citrix ADC VPX, Citrix Virtual Apps Web Interface and Citrix Virtual Apps XML Broker can all be virtualized and can run on the same server. For best performance, ensure that the physical host has enough CPU and I/O capacity to support all the running workloads.

Will adding CPU cores to a single Citrix ADC VPX instance increase the performance of that instance?

Yes, adding CPU cores can improve NetScaler VPX performance, provided the NetScaler VPX instance is licensed for the extra vCPUs. NetScaler VPX can support up to 20 vCPUs (for 41 Gbps - 100 Gbps performance), depending on the configuration and performance tier. More vCPUs can help increase throughput, especially in high-performance scenarios. However, the impact on performance also depends on factors like the network drivers (for example, PCI passthrough or SR-IOV) and the specific workload. For information on number of vCPUs supported for different VPX performance tiers, see NetScaler VPX data sheet.

Why Citrix ADC VPX looks like consuming more than 90% of the CPU even though it is idle?

It is normal behavior and Citrix ADC appliances exhibit the same behavior. To see the true extent of Citrix ADC VPX CPU utilization, use the stat CPU command in the Citrix ADC CLI, or view Citrix ADC VPX CPU utilization from the Citrix ADC GUI. The Citrix ADC packet processing engine is always “looking for work,” even when there is no work to be done. Therefore, it does everything to take control of the CPU and not release it. On a server installed with Citrix ADC VPX and nothing else, results in looking like (from the Hypervisor perspective) that Citrix ADC VPX is consuming the entire CPU. Looking at the CPU utilization from “inside Citrix ADC” (by using the CLI or the GUI) provides a picture of Citrix ADC VPX CPU capacity being used.

System requirements

What are the minimum hardware requirements for Citrix ADC VPX?

The following table explains the minimum hardware requirements for NetScaler VPX.

Note:

For critical deployments, 4 GB memory is preferred for NetScaler VPX. With 2 GB memory, NetScaler VPX operates in a very memory-constrained environment. This might lead to scale, performance, or stability related issues.

For more information on system requirements, see NetScaler VPX data sheet.

Note:

AMD processors are not supported.

What is Intel VT-x?

These features, sometimes referred to as “hardware assist” or “virtualization assist,” trap sensitive or privileged CPU instructions run by the guest OS out to the Hypervisor. This simplifies hosting guest OSs (BSD for a Citrix ADC VPX) on the Hypervisor.

How common are VT-x?

Many servers have virtualization assistance features (such as VT-x or AMD-V) disabled by default in the BIOS settings. Before concluding that you cannot run NetScaler VPX, check the BIOS configuration. If virtualization support is disabled, you may need to enable it in the BIOS to ensure your server can properly run virtualized applications like NetScaler VPX.

Is there a hardware compatibility list (HCL) for Citrix ADC VPX?

As long as the server supports Intel VT-x, Citrix ADC VPX must run on any server compatible with the underlying Hypervisor. See the Hypervisor HCL for a comprehensive list of supported platforms.

What version of Citrix ADC OS is Citrix ADC VPX based on?

Citrix ADC VPX is based on Citrix ADC 9.1 or later releases.

Since Citrix ADC VPX runs on BSD, can it be run natively on a server with BSD Unix installed?

No. Citrix ADC VPX requires the Hypervisor to run. Detailed Hypervisor supports can be found in Citrix ADC VPX data sheet.

Other technical FAQs

Does link aggregation on a physical server with multiple NIC’s work?

LACP is not supported. For the Citrix Hypervisor, Static link aggregation is supported and has limits of four channels and seven virtual interfaces. For VMware, static link aggregation is not supported within Citrix ADC VPX, but can be configured at the VMware level.

Is MAC based forwarding (MBF) supported on VPX? Is there any change from the Citrix ADC appliance implementation?

MBF is supported and it behaves the same way as with the Citrix ADC appliance. The Hypervisor basically switches all the packets received from Citrix ADC VPX to the outside and conversely.

How is the Citrix ADC VPX upgrade process carried out?

Upgrades are performed the same way as for Citrix ADC appliances: download a kernel file and use install ns or the upgrade utility in the GUI.

What is the size of the /var partition when using the default image for VPX? How to increase the disk space?

The size of the root disk is limited to 20 GB to keep the disk image small.

If you want to increase the /var/core/ or the /var/crash/ directory space, attach an extra disk. To increase the /var size, currently, you must attach an extra disk and create a symbolic link to /var, after copying the critical contents to the new disk.

What can we expect to regard the NetScaler VPX build numbering and interoperability with other builds?

Citrix ADC VPX has similar build numbering as the 9.1. Cl (classic) and 9.1. Nc (nCore) release, for instance 9.1_97.3.vpx, 9.1_97.3.nc, and 9.1_97.3.cl.

Can the Citrix ADC VPX be a part of a high availability setup with a Citrix ADC appliance?

Not a supported configuration.

Are all the interfaces visible in Citrix ADC VPX directly related to the number of interfaces on the Hypervisor?

No. You can add up to seven interfaces (10 for VMware) through the Citrix ADC VPX configuration utility with only one physical NIC on the Hypervisor.

Can Citrix Hypervisor XenMotion or VMware VMotion or Hyper-V live migration be used to move active instances of Citrix ADC VPX?

Citrix ADC VPX does not support XenMotion or Hyper-V live migration. VMotion is supported from Citrix ADC 12.1 release onwards.