Applying traffic management/bandwidth controls for asymmetric links in Multi-WAN/SD-WAN setup
This is one of those scenarios that will be coming up for a few Fireboxes that I manage and am wondering what the best way to implement this is.
The Fireboxes in question (mostly M270s, but my home one is a T35-W with a similar issue) will be getting a second Internet connection, however at least one of the connections requires traffic management rules to be applied, particularly for the uplink, otherwise the network provider will throttle the traffic quite badly.
Complicating the setup is that the link is asymmetric, so it does not appear to be as simple as putting the bandwidth value against the interface.
eg. on a 100/20Mbps link, if we don't throttle the uplink to 20Mbps by using traffic management, it affects both upload and download - note the download does not need throttling.
This is fine for a single policy, however the complication is when we want to use Multi-WAN, since the two links are not the same speed (in most cases, the primary is a symmetric 100Mbps link, and only the backup is 100/20Mbps or similar).
If we apply traffic management rules against a policy (eg. limit uploads to 20Mbps), it would also apply when the primary link is in use, which we don't want.
Another way of putting this:
Is there a way to apply bandwidth rules against an interface where the link is asymmetric?