Unexpected Result 2 x FTTP Lines

Today I got my second FTTP line up and running, set up for load balancing via my Draytek 2962 router.

In testing the set up I noticed something strange, speedtests via Ookla actually some how combine the speed of the two lines. This happens whether trying it via PC or iPhone.

My expectations were that the router would just use the least busy line and the speedtest results would be of the single line only.

This is of no real world use as is it only the Ookla test that seems to benefit from the combined speed. File downloads and the Thinkbroadband multi thread speed test only use one line.

I was just intrigued how Ookla is doing this, I would have thought it impossible without having a bonded service with hardware at the ISP's end to support it.

In reply to a post by Ripley:

Today I got my second FTTP line up and running, set up for load balancing via my Draytek 2962 router.

In testing the set up I noticed something strange, speedtests via Ookla actually some how combine the speed of the two lines. This happens whether trying it via PC or iPhone.

My expectations were that the router would just use the least busy line and the speedtest results would be of the single line only.

This is of no real world use as is it only the Ookla test that seems to benefit from the combined speed. File downloads and the Thinkbroadband multi thread speed test only use one line.

I was just intrigued how Ookla is doing this, I would have thought it impossible without having a bonded service with hardware at the ISP's end to support it.

Load balancing will cycle new connections across both lines and as Ookla use multiple servers, you get a mix across them all. I'm surprised it doesn't work on TBB, pretty sure it did when I tried.

The drawback is some sites such as Banking will throw a fit at this, so ideally you have a router you can put policy routing rules into which use Failover instead for those IP addresses. Its one reason I use pfSense rather than a consumer router.

This should happen on Steam, Xbox, Playstation too - anything that does multi-threaded downloads from different IP addresses.

My question though would be, why have two services? Are both lines provided by Zen over the same service? If so it may be a different fibre into the house but it will be off the same splitter in the street, so in all likelihood if one goes down, both go down.

Edited by alexatkin (Sat 09-Dec-23 00:12:48)

Its a well documented feature of Draytek's. Session based load balancing, i.e. it will send multi-session connections over all available WAN's, usually by default. They can of course be configured not to do this and to combat banks etc throwing a wobble by default certain ports are configured not to load balance in this way, on mine ports 80, 443 for example.
I have 3 wan's via a 3910 and have never had any issue with bank sites or indeed anything else when set to load balance sessions. It just works and spreads the load.
In practice most things will stick to one WAN, but as you have found out speedtests look great!

Edited by Rolandrat (Sat 09-Dec-23 04:50:46)

That's unfortunate given most downloads will be over 443 so its functionally useless. But then that's what more advanced router OS are for where you can define your own policies.

Until recently I had all Steam IPs go over both WANs, but recently Steam is performing a lot worse in general so I stopped as it was actually slower.

I will sometimes send specific LAN devices down a specific WAN though, if they are less sensitive to the variable latency over 5G.

In reply to a post by alexatkin:

That's unfortunate given most downloads will be over 443 so its functionally useless.

Yeah, but most downloads on port 443 are a single TCP stream anyway, so it doesn't make any difference.

The Speedtest opens 6 (I think) concurrent TCP streams, to the same destination, which fills them all as fast as it can. If the Draytek splits them as 3 and 3 then you'll fill both pipes.

Those sessions will be coming from two different ISP's IP addresses. I don't know if the Speedtest service is clever enough to work out that you got X Mbps from ISP A, and Y Mbps from ISP B. I suspect it will attribute the whole throughput to whichever ISP's connection was used to hit the front-end web page, in which case you will be skewing their stats for ISP A

I have a 2927 and I use the IP based load balancing option. Never have any issues with e.g. Banking sites. Great routers but way too many options for my simple brain. 😊

The solution I'm using is a tad more expensive and enterprise-y than a Draytek but has a software toggle for 'session affinity'. I can set a timer in seconds and any new connection between a pair of IP addresses within that time limit will use the same WAN link as an earlier one to ensure consistency of source address.

Unsure if Draytek would be open to a feature request but that's a good one.

In reply to a post by candlerb:

In reply to a post by alexatkin:

That's unfortunate given most downloads will be over 443 so its functionally useless.

Yeah, but most downloads on port 443 are a single TCP stream anyway, so it doesn't make any difference.

The Speedtest opens 6 (I think) concurrent TCP streams, to the same destination

I thought that was the point, it limits per destination not per stream, in order to not break banking sites. So concurrent streams to the same destination will be locked to a single WAN.

I wouldn't say most downloads are a single stream at all, all the game consoles and gaming services use multi-threaded downloads which is likely where the bulk of peoples downloads are happening. Before I had Gigabit I made extensive use of this fact to load balance across two 80Mbit DSL connections.

You can also get browser add-ons to do multi-part downloads, though granted most people wont bother as they aren't regularly downloading large files through the browser.

Yes it does skew the results on TBB speed test as I accidentally did it and it showed up on the speed map for my post code. Even speedtest.net suffers from this issue.

Edited by alexatkin (Sun 10-Dec-23 18:56:24)