The Dashboard provides several options for uplink selection policies when creating an SD-WAN policy, based on the following default policies shown in Figure 6-2 and discussed in the following paragraphs. These default policies are designed to assist in a quick and easy deployment for the most common use cases and provide excellent results without requiring manual thresholds to be defined on a per-network basis.
• Default policy or Connection Monitor Failover: Shown as WAN1, WAN2, or Global Preference on the Dashboard. These policies require the recorded loss rate to be at least 60 percent loss before failing over from the chosen uplink to an alternate transport network. This policy type also ensures that failover would not happen if the alternate transport network also has >60 percent loss, to prevent failing over to another poor connection.
Pro Tip
When specifying either WAN1 or WAN2, (not Global Preference) the default failover criteria can be overridden by using a custom performance class, similar to when configuring Load Balancing.
• Load Balancing: This policy is recommended to take full advantage of a Meraki SD-WAN solution and balances traffic flows across all available uplinks that satisfy the requirements of the selected performance class. By default, the Dashboard provides only a single performance class, VoIP, but additional custom performance classes can be created.
• VoIP: This performance class requires the MOS of an uplink to be >3.5 to be considered an acceptable path. Flows will otherwise follow any other traffic routing policies to determine their transport path out an acceptable uplink. The 3.5 MOS value is set based on the cut-off for common CODECs used for VoIP and to help optimize the selected transport path for a higher quality experience. While this class is labeled VoIP, it is not specifically limited to VoIP traffic in any way and can be used with any traffic selection filter.
• Best for VoIP (Best MOS): This policy results in choosing the best available transport path based on the highest MOS result. Related flows will immediately prefer the currently best-performing path across all available transport paths. This class is very sensitive to loss metrics. While this policy is labeled VoIP, it is not specifically limited to VoIP traffic in any way and can be used with any traffic selection filter.
Pro Tip
These predefined policies exist to give you a starting point; tuning the environment to known codecs used by the business or known application parameters (e.g., Citrix traffic sensitive to 150-ms latency but more resilient to loss) is highly recommended.