XenClient Enterprise 4.5

1. XenClient Enterprise 4.5 Network Bandwidth Policies

2. Table of Contents

3. Managing Bandwidth in Network Infrastructure • The Synchronizer provides some basic bandwidth control policies which are the topic of this document. • But wherever possible, best practice is to leverage Quality of Service or other bandwidth-limiting features in network infrastructure instead. • This can give much more flexibility and control over network bandwidth management in a XenClient Enterprise deployment.

4. Engine vs. Synchronizer Bandwidth Policies • XenClient Enterprise provides two types of bandwidth policies: • Engine Bandwidth Policy • Configured in the Engine policy. • Sets limits for individual computers. • Not commonly used. • Synchronizer Bandwidth Policy • Configured as a separate policy applied to Synchronizer servers. • Limits total bandwidth for all network communications: • Between registered computers and Synchronizer servers. • Between remote servers and the primary server. • This policy does not limit SQL network traffic for remote servers. • Much more commonly used than Engine bandwidth policies.

5. Engine Bandwidth Policy Enforcement • Engine policy bandwidth limits are enforced in the Engine. • Each individual Engine will comply with the policy settings. • With multiple computers registered to Synchronizer: • Each Engine might use up to the maximum configured bandwidth. • Maximum network load on Synchronizer might be much higher. 200 kb/s limit 200 kb/s limit 200 kb/s limit up to 600 kb/s

6. Synchronizer Bandwidth Policy Enforcement • Synchronizer policy bandwidth limits are enforced in the Synchronizer. • Each Engine will try to download files as fast as the network will allow. • If only one computer is downloading an update, it might use up to the maximum configured bandwidth. • If multiple computers are downloading updates, the total download bandwidth is limited by the policy. max 200 kb/s

7. Synchronizer Bandwidth Policies and WAN Links • A distributed Synchronizer configuration example is shown below. • Synchronizer bandwidth policy is commonly used to protect the WAN link otherwise the WAN link can get flooded with download traffic. • Bandwidth policy should be set to a fraction of the WAN link bandwidth. • To leave bandwidth available for other purposes. • Example: for a T1 link (1.5 Mbps), the bandwidth limits might be set to 512 kbps. • Engine bandwidth policy would not be of much help in this situation. Primary Server Remote Server WAN Link Remote Network (10.1.2.0/24) Primary Network (10.1.1.0/24) Primary Server Computers Remote Server Computers

8. Engine Bandwidth Policy Configuration • Engine bandwidth policy settings are part of the Engine policy. • Locate the Engine policy in Synchronizer console. • Select “Network”. • Enter values for the maximum Engine upload and download speeds. • Units are kilobits per second. • Policy changes will take effect when the computer next checks for updates.

9. Synchronizer Bandwidth Policies: Required Steps • Setting a bandwidth policy for a Synchronizer server is a multi-step process. • The bandwidth policy must be defined in the Synchronizer console. • Bandwidth management must be enabled for a Synchronizer server. • The bandwidth policy must be assigned to the Synchronizer server. • The Synchronizer service should be restarted. This is the best way to make bandwidth policy changes take effect immediately. • These steps are outlined on the following pages.

10. Creating a New Synchronizer Bandwidth Policy • There is a separate folder for Synchronizer bandwidth policies. • To create a new policy: • Select the “Bandwidth” policy folder. • Click “Create” and select “Bandwidth Policy”.

11. Synchronizer Bandwidth Policy: IP Address Range • Each bandwidth policy applies to a range of IP addresses. • The IP Address property defines the beginning of the range. • The Subnet Mask property defines the length of the range. These settings define an entire Class C network (10.1.2.0/24). These settings define an entire Class B network (10.100.0.0/16). A single IP address can also be defined if desired.

12. Synchronizer Bandwidth Policy: Bandwidth and Connections • These properties are fairly self-explanatory. • Download and upload units are in kilobits per second. • Not kilobytes per second. • Bandwidth limits are total limits across all connections within the IP address range defined for the bandwidth policy. • Do not make the connection pool sizes too small. The minimum recommended size is 20.

13. Synchronizer Bandwidth Policy: Time In Effect • If desired, the bandwidth policy can be configured to only be in effect during certain times and/or on certain days of the week. • This is often done to maximize transfers between primary and remote Synchronizer servers across WAN links during non-working hours.

14. Enabling and Assigning Synchronizer Bandwidth Policies Select the Synchronizer server that the bandwidth policy should be applied to. Select the “Bandwidth” tab. Select “Enable Management” . Assign bandwidth policies to the server, then save changes.

15. Primary and Remote Synchronizer Servers • Bandwidth policies can be applied to the primary and/or remote servers. • Different servers might have different policies applied. • When a remote server downloads a resource from the primary server: • Bandwidth is limited by policies in effect on the primary server. • Controlling policy is based on the remote server IP address.

16. Bandwidth Policy Scope • If a bandwidth policy is applied to a Synchronizer server, the following types of network traffic are limited: • The download limit is applied to client computers, or remote Synchronizer servers, downloading VM image updates and other resources from the repository. • The upload limit is applied to client computers uploading user backups to the Synchronizer repository. • Examples of network traffic not limited by the bandwidth policy: • Use of the Synchronizer console. • Direct communication between remote Synchronizer servers and the SQL database. • Direct communication between remote Synchronizer servers and Active Directory. • This traffic should be trivial compared to downloading VM image updates or uploading user backups.

17. Multiple Bandwidth Policies • Multiple bandwidth policies can be assigned to a Synchronizer server. • Each policy defines a different range of IP addresses. • Bandwidth limits are enforced individually on each set of IP addresses. • This applies to upload or download speeds and number of connections. Remote Network (10.1.3.0/24) Remote Network (10.1.2.0/24) Up to 200 kbps Up to 200 kbps Up to 400 kbps

18. Overlapping Bandwidth Policies • Overlapping bandwidth policies can be assigned to a server. • For a client with an IP address in the overlapping range, the policy with the most restrictive bandwidth limits is applied. 10.0.0.0/8 This group of clients is limited to a total bandwidth of 1000 kbps. 10.1.0.0/16 Total network load for all three groups could be up to 1700 kbps. This group of clients is limited to a total bandwidth of 500 kbps. 10.1.2.0/24 This group of clients is limited to a total bandwidth of 200 kbps. 192.168.0.0 – 192.168.255.255 There is no bandwidth policy for this group of clients so they are unrestricted.

19. Most Restrictive vs. Most Specific • When a client connects to Synchronizer, the client IP address is used to choose the controlling bandwidth policy. • If multiple policies apply to the client IP address, the policy that gets chosen is the one that is more restrictive (in terms of bandwidth limits), not more specific (in terms of IP address ranges). Example 1: The more specific policy is less restrictive. Both sets of clients are controlled by the first policy. 10.0.0.0/8 10.0.0.0/8 10.1.1.0/24 10.1.1.0/24 Example 2: The more-specific policy is also more restrictive. The two sets of clients are controlled by different policies.

20. What If More Flexibility Is Required? • Synchronizer bandwidth policies are fairly basic and might not provide the desired level of flexibility.For example, it may be desired to restrict bandwidth for all IP addresses, except for those in a particular range. • For these types of requirements, it is best to leverage Quality of Service or bandwidth management features provided by network infrastructure (switches, routers, firewall appliances, or other components).