This is a review of the potentially excellent TP Link TL ER5120 load balancing router. As you will discover it has a fatal flaw. But do read on
Marcus and Agata currently investigate the possibility to combine a number of weak and insufficient Internet connections (copper line, mobile, mobile tether etc) into a single more powerful Internet connection that would suit our needs.
Spoiler alert: We thought it would work, but turns out there was a fatal flaw
Combining Internet feeds is kind of non trivial. The idea is that you don't want to provide Load Balancing but Aggregation. The difference?
Well, in the load balancing scenario all the computers requesting an Internet connection in your house pass through a Black Box. It's connected on the output to all your mediocre Internet feeds. In our testing we had 3 concurrent Internet connections.
For Load Balancing an individual computer application or even a single web request passes thru the Black Box (our TL-ER5120) and is scheduled to go out onto the least loaded Internet Connection.
In this way each computer or application never gets faster than any single Internet connection.
Contrast this to aggregation when individual requests from an application are sent alternatively to different Internet feeds. So a best case example, say a torrent application talks out all Internet feeds and achieves a higher throughput
This is the case in this panel were both boxes are unchecked and so an individual application is sprayed out over multiple Internets, in our testing 3 lines.
We did some prior technical analysis and apart from coding some Linux IP masquerading magic up yourself; the number of Load Balancing routers is pretty thin in the non Enterprise marketplace.
TP link has 3 models above and only the ER5120 has Gigabit ports and a claimed VPN capacity of 350 Mega Bits Mbps. We shall see!
Lots of Facilities
Decent summary page
NAT and other modes
You can have one or more WAN ports. Totally configurable. Brilliant. For example 4 Internet feeds and one output LAN feed.
Set the parameter of each WAN link.
Set the IP address of the output LAN link
Really decent DHCP facilities
Specific Port mapping
Configure a link to be a backup if a Primary fails
Quite a decent set of Firewall facilities.
With the ease of use Menu I was looking forward to giving this router a really positive review. But there is a terrible terrible flaw
On faster links: The aggregation actually makes things slower
Quick example download using 2 links at 3.1 MB/second
And yet each single link is about 3.6 MB/second.
To repeat, the aggregated link is actually slower than a single link. The results using Speedtest were even worse
1 Link native (no router): Speed 7.1 MB/second
1 Link thru Router: 6.5 MB/second
2 Links on Router: 4.5 MB/second
Again using 2 Internet connections with a probable maximum of over 10 MB/second resulted instead in less than 5 MB/second.
It's almost like the internal OS doing the packet or traffic splitting just can't work fast enough.
NB: For aggregation of slower connections say 2 x 1MB/second connections this router works as you might expect: it works
REALLY a great shame.
A Sad Goodbye
I kept thinking of justifications to keep this router and could not find enough. It could be used as a pretty decent firewall or in failover mode you can configure a second line to take over when the first dies.
But this is really not a justification. It needs to go back :-(
The config is now wiped and the device sent back, because at the end of the day, aggregation of two 7MB/second lines fails miserably. I am so gutted.
TL ER5120 Specs