Stacking FEC and WAN Smoothing?

Hi all, I’ve been trying to get a sense for whether or not FEC and WAN Smoothing are something that should be employed together or not. I am willing to use whatever extra bandwidth is necessary to achieve a flawless video conferencing experience. To date, I’ve been using ‘Normal’ WAN Smoothing and ‘Low’ FEC. But after doing some additional reading this morning, I am wondering if this is the best approach.

Also, can anyone confirm that ‘Normal’ WAN smoothing is essentially the same as ‘Maximum’ when you are only working with 2 connections? (I.e. are there any advantages to going above Normal with only 2 WAN)

I often use them together. WAN smoothing is really a way to mitigate high latency events on a single WAN (by duplicating the traffic on another WAN link with more stable latency at that moment in time), a side effect is that if a link has packet loss you’ll likely receive that lost packet on the other link.

FEC is about packet loss primarily, infilling lost packets on the fly from simultaneously transmitted parity data.

So long as you have a powerful enough router and enough bandwidth I don’t see a good reason why not to use WAN smoothing and FEC at the same time. The only time I don’t is when streaming video on the move as WAN smoothing tends to work more reliably by itself when the WAN links are very variable / volatile from a latency perspective during video transmission.

You have Two connections locally, how many connections at the remote end? Normal WAN smoothing will duplicate traffic across 2 tunnels, Max duplicates it across all tunnels. If you only have two local and 1 remote WAN then this is the same thing. If the remote has two WANs also then you’d double the bandwidth usage again going from normal to Maximum.

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Thanks Martin! I have Starlink and an LTE-based internet service. They have similar latency with the LTE connection having a slight edge (20-30ms average LTE vs 50-60ms average Starlink).

My setup right now is just one Peplink Balance One Core using SFC to Seattle (I’m in Alberta). I’ve got a default tunnel that I route all my day to day work machine’s traffic through and a secondary ‘streaming’ tunnel that I route Zoom and Teams traffic to.

Do you to the receive buffer at all? I am apprehensive about adding latency to my connection for this because the LTE based connection is usually pretty rock solid on its own. I feel the provider has QoS in place for video conferencing. So one downside to using SFC is we don’t get to benefit from QoS at the carrier level.

Lovely - have been seeing more and more Peplink Starlink in combo lately.

OK great. That doesn’t need WAN smoothing i would suggest, just hot failover.

WAN smoothing on that would make a big difference for sure.

Yes, but only rarely as no one likes additional latency.
FEC on the transmit end and the receive buffer enabled on the other end can really help with large file transfers (that aren’t real time in nature like backups).

Unlikely from my experience, but it would be interesting to try and test for that. The only optimisation I regularly see on LTE networks is for for obvious reasons.

I have seen ISPs that manage and shape VPN traffic over their networks, so what you might be seeing is that traffic management rather than specific attempts at optimisation…

One thing to keep a close eye on is available upload bandwidth on LTE. Make sure you set the available upload / download bandwidth values for each WAN so they are representative of actual bandwidth on each link and do turn on PepVPN traffic Optimisation and Cable Optimisation in Network > QoS > Application as these help in instances where bandwidth is asynchronous (as is the case with both Starlink and LTE).

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