Bandwidth Management and VLANs
Two of the 2900G's features not commonly found on consumer-grade routers are its Virtual LAN (VLAN) and Rate (bandwidth) Control features (Figure 9).
Figure 9: VLAN and Rate Control settings
Both features are applied to clients connected to the 2900G's physical ports, so are somewhat limited in flexibility. Still, it's nice to see these features incorporated into a consumer-priced product.
You get a matrix of four VLANs and four ports, so VLAN assignment is as easy as checking the appropriate boxes. Clients in the same VLAN will be able to communicate with each other and with the Internet, but not with any other clients.
Rate Control sets the upper speed bound of inbound and outbound traffic from each of the 2900G's four ports. Anyone who is plagued by family members who monopolize the broadband connection will be able to put this feature to good use. Figure 9 shows you can set throughput caps in increments of 32kbps in each direction separately.
My testing showed that both features worked well. Putting clients in different VLANs kept them from being able to ping or connect to each other, but still allowed Internet access. Bandwidth control also worked as you'd expect with average throughput maintained pretty close to the set rate. But the way the capped throughput is maintained is interesting.
Figure 10: Rate control throughput characteristic
Figure 10 shows a Chariot throughput plot that starts out without Rate Control, then kicks it in with a cap of 2048 kbps. You can't really tell from this plot, but a run I did with a rate cap of 2048 kbps for the entire run had an average throughput of 1967 kbps over a 30 second measurement.
Another side effect I noted with rate limiting cranked down in the 100's of kbps was the the web admin interface response became very sluggish while the Chariot test was running. Most users probably wouldn't notice any slowdown with normal intermittent web traffic, but if you have a busy LAN you might.
Note that neither feature works on the wireless part of the 2900G, although DrayTek said that's on the list for a future firmware upgrade. I hope they also enhance the Rate Control feature to include port (application) and user (IP or MAC address) based controls, which would make a good feature even better!