| Solution |
Why SD‑WAN rules treat parent/child applications differently from Traffic Shaping:
Background:
Applications in App Control can be identified either at the parent or child level:
- Parent application = the general category (e.g., Microsoft Teams).
- Child application = specific sub‑traffic within that parent (e.g., Teams.Audio or Teams.Video).
This distinction matters because Traffic Shaping and SD‑WAN rules handle parent/child matches in different ways.
Example Application Hierarchy:
- Microsoft Teams (Parent):
- Microsoft Teams.Audio (Child).
- Microsoft Teams.Video (Child).
- Other Microsoft Teams traffic (broadcast, signalling, events, etc.)
Design Goal:
Apply the following policies:
- Teams.Audio -> Priority queue (low latency).
- Teams.Video -> Non‑priority queue, with reserved bandwidth.
- Other Teams traffic -> Best effort queue.
Traffic Shaping Behavior.
Traffic shapers can evaluate child apps separately:
- Teams.Audio -> put in the priority queue.
- Teams. Video -> put in non‑priority queue with bandwidth reservation.
- Other Teams traffic (only matches the parent app) → goes to best effort.
Traffic Shaping keeps child‑level granularity even if the parent is also present in the ruleset.
SD‑WAN Rule Behavior:
SD‑WAN classification works differently:
- If a rule references Microsoft Teams (parent), all Teams traffic matches this rule, and child rules below it are ignored.
- The rule matching order is:
- Internet‑Service‑Custom
- Internet‑Service‑App‑Ctrl
- Internet Service Database
When the parent (Microsoft Teams) is matched, SD‑WAN does not try to identify children afterward.
Config Example:
Rule 1 – Teams Audio.
- Match: Microsoft Teams.Audio
- Action: Priority path, priority queue
Rule 2 – Teams Video.
- Match: Microsoft Teams.Video
- Action: Secondary path, bandwidth guarantee
Rule 3 – Other Teams traffic.
- Match: Microsoft Teams (Parent)
- Action: Best effort path
Result of testing:
- Teams.Audio -> correctly classified into Rule 1 (priority).
- Teams. Video -> correctly classified into Rule 2 (non‑priority with reserved bandwidth).
- Teams broadcast/other signalling -> caught only by Rule 3.
- If Rule 3 is placed above Rule 1/2, then all Teams traffic hits Rule 3 and child rules are bypassed.
Key Takeaways:
- Traffic Shaping can apply to parents and children simultaneously.
- SD‑WAN rules stop at the first parent match: therefore, avoid referencing the parent app if more granular control is required.
- Best practice: reference only the child applications needed in SD‑WAN, and keep the parent app separate for fallback/best effort rules.
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