For the past couple years, our home network has had a fairly typical setup: DSL Modem hooked up via PPPoE to a LinkSys 8-port wired router, which handles DHCP, firewall, port forwarding, etc.

Recently, I've put together a dedicated fileserver/media player Ubuntu box that also handles our BitTorrent activity. There have been some slowdowns when multiple torrents are open, even though our WAN bandwidth isn't close to being consumed. This leads me to suspect that the router might actually be the bottleneck. So, I'm thinking, since we now have an always-on server-type box, is it worth replacing the router's functionality with a software solution?

I've heard rumours that consumer routers have limits to the number of active connections, and can be slower than a linux box used as a router. I'm unable to find anything concrete, though: Does anyone know if this is true?

I've also looked into RP-PPPoE a bit, but am also looking for a utility that will run some benchmarks on our DSL connection, for latency, bandwidth, etc. Does anyone know of a software package that can accomplish this? Is there a better choice than RP-PPPoE for connecting to a DSL modem?

Comments, ideas or discussion would be appreciated!

Those small "hardware" routers are really software routers. That is, they run an operating system on a small CPU and use software to route packets. True hardware routers are way too expensive for home use, and use ASIC (application specific integrated circuits) to speed routing.

Knowing that the little home boxes are really software routers, it then becomes clear that even a very moderate PC will outperform them. After all, even an older PC will have 20-200 times the resource of the little standalone routers.

Good point, hadn't thought of that.

At what point, however, does whatever dinky little embedded CPU these routers have run out of juice and affect performance? I've read articles claiming that a 486 can saturate a 100Mb/s line without breathing hard - but I also know there's a difference in the workload required to process, say, a single-socket FTP download versus the hundreds of connections used in BitTorrent. I don't question that the AMD 1400+ in my Ubuntu box will outperform the router's CPU by several orders of magnitude, but will that actually affect network traffic?
Does anyone have benchmarks or experience in going from a commodity router to a linux-based PC setup, with BT-like traffic? Would I be adding power, or just complexity?

There are too many variables to make a meaningful benchmark that would be of use in any given situation.

In general, the more features, the more CPU instructions in the path, and the more resources consumed. For example, the consumer routers typically have a problem when the number of VPNs in use exceed one or two. If that's all you need, they are adequate. If you need 5 VPN sessions, MAC filtering, forwarded ports and stateful packet inspection, the poor little things will explode (reboot, or sometimes even hang requiring manual reset).

Unfortunately, monitoring resources consumption (CPU and memory utilization, packets per second) on consumer routers isn't usually possible, so their limits are more hit and miss. On a full Linux system, you can just run top and ntop. If you are comfortable with Cisco IOS, you can run Zebra. So you get not just capacity, but functionality and compatibility.

While your points are valid, I really doubt he would have any problem in his situation.

I have pounded my WRT54G 24/7 as long as I have had it, usually running my internet connection at maximum download, while at the same time having 100 Mbps traffic over it's switch to my file server. I run at least 6 torrents on two different machines simultaneously nearly full time (do the math, that is easily 1200+ connections even on slow torrents).

I have never had a problem with this router. Older, lower quality routers however have crashed under my usage.

If he is getting a high quality router like the WRT54G (which runs Linux by the way) there is very little chance he is going to run it hard enough to crash it.

On the other hand, a machine running something as heavy as Ubuntu could have slowdown or lag, even if it is a powerful machine, simply because there are just so many software programs and services running on the machine, and there are plenty of opportunities for lockups or shudders.

If you really think you can pull enough bandwidth to slow down a high quality SOHO router, you would be better off running something like SmoothWall on a spare machine, instead of Ubuntu.