Branch Cache client download behavior
As far as we know, the branch cache client download behavior is as follows:
- New package with a required deployment is being sent to a location with its own subnet
- Clients which received the deployment will start downloading the related content
- As soon as at least one client completely downloaded all content of the deployment, the other clients in the same subnet will start using this (and subsequent) client(s) for content download, which will then cause no WAN consumption anymore
However, this typically still causes quite a lot of WAN bandwidth consumption: as long as the “first” client at least hasn’t finished downloading the full package yet, other clients will still start downloading one and the same package as well. This is particularly bad when it comes to required deployments to a lot of users in a location with a poor WAN in front.
That being said, we suggest the following behavioral change.
- New package with a required deployment is being sent to locations
- Before clients start downloading the related content, they will check their subnet for any other clients, if they already started downloading the content of the related deployment
If the result is “Yes”, they will wait until the other client(s) finished downloading that content
- As soon as at least one client completely downloaded all content of the deployment, the other clients in the same subnet will start using this and subsequent clients
This behavior will cause much less WAN bandwidth consumption and prevents “stuffed networks” when it comes to required deployments to a location without an own distribution point.