Fair Share calculation for Bandwidth provisioning on SD-WAN
Article ID: CTX256716
Updated On:
Description
By default, all branches and WAN services (Virtual Path/Internet/Intranet) receive equal share of the bandwidth.
When there is high difference in terms of bandwidth requirement or availability between the connecting sites, provisioning can be changed accordingly. By default, the ratio is 1000 (Shares of Group).
Configuration —> Provisioning 
Default minimum rates:
- Virtual Path: 80 kbps (including Dynamic Virtual Path type)
- Internet/Intranet: 100 kbps
Note: To set an unlimited Max (kbps) rate, enter '0' (zero) into the cell.
Calculation of Fair share (Kbps):
Based on the above snippet we have three Services: Virtual Path, Internet and Intranet Services.
By default, we define 1000 shares for each service and a minimum bandwidth for control packets i.e. Min (Kbps).
The amount of bandwidth available for fair allocation is based on the total permitted in the group minus the sum of the minimums for each service in the group.
Calculation : 80 + 100 + 100 = 280 Min Kbps (Reserved)
: 3000 Kbps (Permitted Rate) – 280 (Min Kbps) = 2720 Kbps
: 2720/3 = 907 Kbps for each Service
: 907 + 80 = 987 Kbps for DC
: 907 + 100 = 1007 Kbps for Internet
: 907 + 100 = 1007 Kbps for Intranet
Fair Shares are nothing but the shares that 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.
Note: All Services receive their Minimum Reserved Bandwidth before Fair distribution, which could result in Groups with equal Fair Shares having different Fair Rates.
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