How to Provision Network Bandwidth in a NetScaler SD-WAN Appliance
Article ID: CTX235586
Updated On:
Description
This article describes how the bandwidth provisioning works in a NetScaler SD-WAN and how to modify the bandwidth provisioning parameters based on the network requirements.
Background
The SD-WAN provisioning allows for the bidirectional (LAN to WAN/WAN to LAN) distribution of bandwidth for a WAN Link among the various services associated with that WAN Link. There are two steps to Provisioning that provide for this bandwidth distribution in a simple and effective way:
- Provisioning Groups: Create and edit groups of bandwidth. (Optional)
- Services: View and edit bandwidth settings for services within a bandwidth group
The Concept of Using Shares
When provisioning bandwidth for networks with a large number of sites, using percentages does not allow for enough granularity as the site count increases. With the Appliance provisioning process, we introduce the concept of Fair Shares. Shares are used to distribute the permitted bandwidth over groups, and services within groups.
With shares, the total number of shares is up to the user, allowing any amount of granularity or precision when allocating bandwidth among the different Groups and Services.
Shares are discussed in more detail in the 'Provisioning Groups' and 'Services' sections.
Provisioning Groups
A Provisioning Group is a container for an arbitrary collection of Services on any given WAN Link. They allow the user to allocate bandwidth at a high-level before drilling down to the individual Services within the Group for fine-tuning. They also provide a boundary for the automatic redistribution of bandwidth within the child Services of the Provisioning Group.
Note: Provisioning Groups are available to simplify the provisioning process and are not required if they are not needed.
Fair Shares
In the Provisioning Groups table, shares are used to distribute the LAN to WAN/WAN to LAN eligible bandwidth, which is the Permitted Rate minus the total Min reserved bandwidth of all Services on the WAN Link. All Services are initially assigned to a Default Group that is allocated all of the eligible bandwidth. The user can create additional Groups and allocate bandwidth to its members by giving that Group some number of Fair Shares. The resulting total bandwidth for all Services in the Group is then shown in the Fair (kbps) column.
Note: All Services receive their Min Reserved Bandwidth before Fair distribution, which could result in Groups with equal Fair Shares having disparate Fair Rates. Fair Rates can also be affected by Service Maximums, if defined.
Services
The Services section allows the user to further fine-tune bandwidth allocation. Services that are assigned to the same group contend for the bandwidth allocated by that group. The services shown in the Services section of the selected WAN Link have been enabled on that WAN Link by the current Configuration.
By default, all services are assigned to the Default group with a default number of fair shares divided evenly among them. The default number of shares serves as a starting point and is not restricted by (nor related to) the number of shares set in the Provisioning Groups section.
- Virtual Path: 80 kbps (including Dynamic Virtual Path type)
- Internet/Intranet: 100 kbps
For the Dynamic Virtual Paths service entry (if configured on the selected WAN Link), the Min (kbps) and Max (kbps) fields are variable. Therefore, the range of values that can be expected is shown.
Shares of Group
In the Services section, shares are again used to distribute the eligible LAN to WAN/WAN to LAN bandwidth. The Group that a service is assigned to determines the eligible bandwidth (listed in the Fair (kbps) column in the Provisioning Groups section) for all services assigned to the same Group. The Shares of Group are used to divide up the eligible bandwidth among the members of a group based on the ratio of the current service divided by the total number of shares for the group in which it is a member.
The Minimum rate acts as a base bandwidth allocation for each service, and the amount of bandwidth available for fair allocation is based on the total permitted for the group minus the sum of the minimums for each service in the group.
In the case of the Dynamic Virtual Paths service, the Shares of Group is divided among all Dynamic Virtual Paths. Please refer to the context help for Dynamic Virtual Path Provisioning for more information.
New services enabled on a WAN Link will be placed in the Default Group with a Shares of Group value of 0 (zero). The Shares of Group must be configured to a non-zero value in order to be valid.
When moving a service between Groups, the Service will keep its configured amount of shares. The shares will be removed from the old group and taken to the new Group.
When deleting or disabling a service on a WAN Link, that service's shares will be removed as well. The shares will not be distributed over the remaining services.
Dynamic Virtual Path Provisioning
The Dynamic Virtual Path Provisioning worksheet is for configuring the parameters of an individual Dynamic Virtual Path. If a Dynamic Virtual Path service is not enabled on the selected WAN Link, the worksheet will be hidden.
The settings in this worksheet should be treated in the same way as a static Virtual Path service. Set the Min (kbps) and Max (kbps) for an individual Dynamic Virtual Path here. Each Dynamic Virtual Path will use the settings provisioned here. Once the Min (kbps) and Max (kbps) rates have been configured, the Fair (kbps) per Dynamic Virtual Path will be recalculated to reflect the new settings.
Using the Possible Dynamic Virtual Paths and the individual Dynamic Virtual Path settings in this worksheet, worst-case usages of Min, Max and Fair bandwidth will be calculated. The worst-case Min and Max bandwidth will be shown in the Min Total (kbps) and Max Total (kbps) columns (respectively) in the Dynamic Virtual Path Provisioning worksheet. The worst-case fair bandwidth will be shown in the Fair (kbps) column of the main Services table for the Dynamic Virtual Paths service.
Note: To set an unlimited Max (kbps) rate, enter '0' (zero) into the cell.
Fair (kbps)
The fair bandwidth is based on a worst-case scenario in which all accounted Dynamic Virtual Paths are up simultaneously. The number of shares for an individual Dynamic Virtual Path are used in the calculation. The number of shares for an individual Dynamic Virtual Path receives in the worst-case is equal to the number of Shares of Group defined for the Dynamic Virtual Paths service divided by the Possible Dynamic Virtual Paths:
For example, if the Dynamic Virtual Paths service has 100,000 shares defined for it in the Shares of Group column in the Services table, and if the current Configuration accounted for a Possible Dynamic Virtual Paths of 4, then 25,000 shares (100,000 / 4) will be used as the number of fair shares for an individual Dynamic Virtual Path.
Once the worst-case number of shares has been calculated, the Fair (kbps) rate is calculated in the same manner as the other service types.
About the Possible Dynamic Virtual Paths column
The Possible Dynamic Virtual Paths value represents the total number of Dynamic Virtual Paths that could exist simultaneously (based on the current Configuration described momentarily). It is either the total number of sites reachable via Dynamic Virtual Path OR the maximum number of Dynamic Virtual Paths supported by the platform being configured, whichever is fewer. Several Configuration parameters cooperate to determine if Dynamic Virtual Paths can be created between sites. Sites that have: Dynamic Virtual Paths enabled AND share a common intermediate site with W-T-W Forwarding enabled AND are in the same W-T-W Forwarding group; can establish Dynamic Virtual Paths between each other and are factored into the Possible Dynamic Virtual Paths value.
Points to consider while provisioning SD-WAN
- By default, all branches and WAN services (Virtual Path/Internet/Intranet) receive equal share of the bandwidth.
- Provisioning sites needs to be changed, when there is high disparity in terms of bandwidth requirement or availability between the connecting sites.
- When dynamic virtual paths are enabled between maximum available sites, the WAN link capacity is shared between the static virtual path to the Data Center and the dynamic virtual paths to the other remote sites.
- The fair share of bandwidth is allocated based on demand for the virtual path which is then subject to the division of bandwidth based on class’s sustained rate configuration.
Instructions
To modify the bandwidth provisioning, open the SD-WAN configuration editor the go to, Advance > Provisioning > (Select the Site) > Wan Links > (Select the WAN Link)
Issue/Introduction
Additional Information
