D-Link's Broadband Router Aims to End Latency

By Jason Cross  |  Posted 2004-12-28 Email Print this article Print

Review: The D-Link DGL-4300 broadband router targets online gamers with the promise to end latency problems. Can it deliver? We spend some quality time with it to find out.

Any serious gamer these days probably has a broadband connection that is often shared by multiple devices. With the help of a small broadband router, which usually has four ports, a gamer can have online access on several computers or game consoles simultaneously.

Your connection speed or hardware isn't necessarily your biggest problem in online gaming, but rather how you and others use your connection at the same time. Typical download speeds range from 768Kbit/sec to 3Mbit/sec, with upload speeds of 128Kbit to 1Mbit. That's more than enough for several people to enjoy broadband-only games online. So why do so many users experience so much lag? Usually something else happens on your home network that slows things down a bit. Peer-to-peer file sharing trashes your network connection, as do really big local file transfers.

D-Link's new GamerLounge broadband routers promise to remedy this situation. Available in both standard wired (DGL-4100) and 802.11g wireless (DGL-4300) models, the GamerLounge routers incorporate technology licensed from Ubicom that promise to keep the games running smoothly. We've examined the wireless version to see if it meets their claims. Continued...

PIC: DGL-4300.jpg TITLE: D-Link DGL-4300
CAPTION: It looks, well, like a wireless router. A black one. -->

It's become very easy to set up broadband routers these days. Just plug in all your computers, use a web browser to connect to the router, and run a setup wizard. D-Link's setup is straightforward and simple, and it handles various connection types quite well (PPPoE, Fixed IP, Dynamic IP). The 802.11g wireless setup runs through a similar wizard that lets you choose wireless type and security options easily. In terms of actual wireless technology, it supports the XtremeG tech that provides increased wireless throughput with other D-Link XtremeG products. There's nothing really new there, and other wireless routers offer similar turbo-G type features.

With any broadband router that handles the chores of giving out local IP addresses and shuffling around Internet traffic between them, there are going to be those times when you need to forward some ports to a specific machine. Some peer-to-peer file sharing programs require this to operate optimally, as do some popular voice chat programs like TeamSpeak. Like similar products, the DGL-4300 uses a web-based setup to change key settings. A page called "Gaming" lets you alter settings like "port forwarding" or "port triggering," which is something of a misnomer, as these settings don't apply exclusively to games. You can forward ports to run game servers as well as to other applications. A nice drop-down box includes loads of popular games and applications with the correct ports already identified, so all you have to do is type in the IP address of the machine you're trying to open up.

The configuration menus are full of the usual expected modern router features: web filters and access control, firewall, and more. The stand-out feature of the DGL-4100 and 4300 is the GameFuel menu. This menu allows you to set up and access the functions that are supposed to keep your games running fast even when you're transferring large files or sharing on a P2P network. GameFuel is actually Ubicom's StreamEngine technology, rebranded by D-Link. In the GameFuel, menu you choose to enable or disable the tech and toggle features like automatic classification or dynamic fragmentation. You can also set up rules for specific applications, identifying them by IP address and/or ports to help let the router know that this is an application that needs priority. The D-Link manual states that Automatic Classification should be adequate in almost all cases.

That's really all there is to making the most of the new GamerLounge routers. Check the little checkboxes, set your uplink speed to the proper value (that's important), reboot the router, and it's "game on!" Does it work as advertised? Continued...

There is only one main feature that distinguishes the DGL-4300 from other gigabit 802.11g wireless broadband routers on the market today (including those from D-Link): GameFuel. This feature, which was previously named StreamEngine, keeps game traffic flow smoothly even in the event other heavy network usage. Actually, it's also meant for any application that is sensitive to latency or packet jitter, like voice-over-IP or videoconferencing.

Large files transferred over the internet impair ping time in games in two ways. First, the file transfer program probably sends large packets, whether it's a big e-mail attachment or chunks of a file you're uploading to other BitTorrent clients. Your computer easily sends this file, very quickly, over the 10/100 or gigabit Ethernet link, but the packets get stuck in a rate adaptation buffer inside your modem because you only have 256Kbit/sec of upstream traffic (your connection speed may vary however). Even if you're lucky enough to have a 1.5 megabit upstream link, your local Ethernet connection is up to 66 times faster.

The second problem involves prioritization of traffic. Games and Variable Input Output Port (VIOP) apps typically send small packets of information at regular intervals, but your modem isn't smart enough to recognize them and give them priority over big huge file transfer packets. If the file transfer packets are delayed by half a second, you wouldn't even notice. But a 500ms delay in your game network latency can make it almost unplayable.

StreamEngine technology employs three methods to get around all this. The first is an uplink rate limiter. Instead of sending a full 100 megabits to your DSL or cable modem and letting it get caught up in the rate adaptation buffer, the router does the rate adaptation and sends only as much data to the modem as your uplink speed can handle. It's critical to set the appropriate uplink speed in the DGL-4300's configuration page.

The system's automatic classification and prioritization of game/VOIP traffic is just as important. By looking at values such as the rate and size of packets, as well as the ports they're going to, the software in the router can determine if there is game or VOIP traffic coming into the buffer. These get processed first, while large packets that aren't time-sensitive get pushed to the back of the queue.

Breaking up these large packets, and packets for jitter-sensitive applications like VOIP, can further help keep the buffer flowing smoothly. Dynamic fragmentation breaks up large packets into smaller ones, creating more opportunities for smaller packets to get into the queue and preventing backups that can cost tens of milliseconds.

In theory, if all this stuff works, the GamerLounge modem's software should automatically detect time or jitter sensitive packets and keep them flowing without delay. In our testing, we found the technology works, but not as well as we wanted. Continued...

For this review, we took the router out of the lab and performed real-world tests in a real-world environment. For a of couple weeks, the router was hooked up to a 3 megabit cable modem shared by three roommates who are all gamers. Each roommate has a gaming computer, multiple console systems, and the occasional wireless device. The computers are all plugged directly into the router, along with some game consoles, a laptop, an Xbox connected wirelessly, and other WiFi devices. In other words, this is exactly the kind of environment this product is made for. If it doesn't work well here, it doesn't work for its intended audience.

It's hard to be perfectly scientific about network game performance. You can set up your own server and measure ping times in a very controlled fashion, but that doesn't reflect what happens in the real world, and it doesn't let you test games where you can't run your own server. In the end, we tested the router simply by using it for two weeks, playing a variety of online games, and recording our observations. At various times throughout the week, we would perform simple A-B tests when we played a particular game with no other network activity and recorded the latency from within the game every few seconds for a minute or two. We then would fire up a big P2P file sharing session using BitTorrent or eMule and run the game again, comparing the new average ping time against the old. This simple measurement of the effect of heavy network usage on network game performance would be taken with the GameFuel technology turned on and off.

This method of testing isn't entirely deterministic because bandwidth usage of the P2P program can vary over time, as well as the performance of the game server we're connected to. Many games also don't give you a true network latency time. Xbox Live games, in particular, hide fine details of your network performance from you. It is, however, an extremely real method of testing such a product. It involves using it the way the customers will, in the DGL-4300's intended environment.

So how does it work? It turns out to be' a mixed bag. With some games, enabling GameFuel caused a major reduction in latency when we had big P2P file sharing sessions going. A couple of games, like World of Warcraft, seemed to show only modest improvement. You could tell it was working, but it's not the panacea we had hoped for. Our best-case scenario showed game latency cut to about 25% with GameFuel activated. That sounds great, but sometimes it's not enough. We were measuring ping times of about 60ms to a particular Counter-Strike: Source server with no network activity. With a big P2P session going in the background and saturating our upstream bandwidth, this would shoot up to about 1200ms. Cutting this down to 400ms is a fantastic feat, but it's not like 400ms is the broadband gaming experience we've come to expect.

Below is a simple chart showing data we collected of ping times in popular games. Bearing in mind that the data was collected in a live, real-world game environment where network situations can change over time, you can see how well the DGL-4300 works in some cases, but not in others.

No traffic / GameFuel OFF Heavy P2P use / GameFuel OFF No traffic / GameFuel ON Heavy P2P use / GameFuel ON
Counter-Strike: Source: 62ms 1217ms 67ms 432ms
World of Warcraft: 94ms 835ms 89ms 556ms
UT 2004: 49ms 935ms 45ms 297ms
Battlefield Vietnam: 93ms 1529ms 102ms 466ms

Other games we tested without visible ping times showed mixed results. Often we saw a drastic reduction in latency, but that reduction wasn't enough to get us back in the range of the "no network traffic" ideal. A few applications didn't show any change at all, though setting up a custom game rule in the router menu would sometimes fix that.

Further, we ran into a little problem with Xbox Live. With the dynamic fragmentation feature enabled, none of our three Xbox systems would connect to the service, giving us an error about our router's MTU value perhaps being too small. It seems as though Xbox Live uses big packets, at least for the initial connection, and it expects them to arrive in one piece. No exceptions, rules, or port forwarding we attempted would let our systems connect. We had to turn off dynamic fragmentation to get our Xbox systems online. Because of this, we had to test with that feature disabled (nobody wants to reset their router every time they fire up their Xbox, and then reset it again when they turn it off). It's possible that dynamic fragmentation would have made a bigger impact in the latency reduction we witnessed. Continued...

Incorporating more traffic-monitoring and shaping intelligence in broadband routers is a great idea. It actually works well most of the time. But is "working well" good enough? You can cut extremely high latencies in half, or to even one quarter and still not get down where you want to be. We found that if we saturated our upstream with heavy file sharing or huge file transfers, the DGL-4300 would usually reduce the ping time a lot, but not enough. With a modest amount of rate-limiting, setting our P2P or file transfer programs to use no more than 75% of our upstream bandwidth, we were able to achieve quite playable ping times.

Then there's the issue of dynamic fragmentation and Xbox Live. We have Xbox systems hooked up directly to the router and through a wireless link, and no matter what we did, we couldn't get them to connect to the service with this feature enabled. It's a shame as it probably plays a large part in the potential of the GamerLounge routers, but it's unusable until they resolve that problem with a firmware upgrade.

The traffic shaping is a nice feature, but not the solution you might be hoping for. It's not going to let you fire off that BitTorrent of the new 500MB game demo with unlimited upload speed and still play games without messing up your ping time. It helps, but doesn't quite get you there. On the other hand, any serious improvement is worth a few extra bucks. All traffic management aside, this is still an excellent 4-port gigabit 802.11g wireless router with good management software and an easy setup.

If you're a gamer who wants to upgrade your router connection, check out our article on Four Broadband Routers for Gaming.

You pay a premium for the StreamEngine technology. Typical 4-port wireless broadband routers cost under $100, and you can get into gigabit for perhaps $30-40 more. That means at $179, the DGL-4300 weighs in with a price hike of about $50 (the non-wireless DGL-4100 model costs $149). If you have a local network heavily trafficked by gamers and file sharers, it could be worth it. D-Link and Ubicom still need to work to improve the technology and resolve the conflict with Dynamic Fragmentation and Xbox Live, though. With a firmware patch or two, it could be a must-buy, and the next generation of this technology will be something to keep your eye on.

Product: DGL-4300
Web site: www.dlink.com
Pros: Traffic-management features help reduce ping times; good setup menus and features.
Cons: Costs more than competing routers; dynamic fragementation feature doesn't work with Xbox Live.
Summary: Not a total panacea for gamers and file sharers; but a big step in the right direction.
Price: $179

Jason Cross Jason was a certified computer geek at an early age, playing with his family's Apple II when he was still barely able to write. It didn't take long for him to start playing with the hardware, adding in 80-column cards and additional RAM as his family moved up through Apple II+, IIe, IIgs, and eventually the Macintosh. He was sucked into Intel based side of the PC world by his friend's 8088 (at the time, the height of sophisticated technology), and this kicked off a never-ending string of PC purchases and upgrades.

Through college, where he bounced among several different majors before earning a degree in Asian Studies, Jason started to pull down freelance assignments writing about his favorite hobby—,video and computer games. It was shortly after graduation that he found himself, a thin-blooded Floridian, freezing his face off at Computer Games Magazine in Vermont, where he founded the hardware and technology section and built it up over five years before joining the ranks at ExtremeTech and moving out to beautiful northern California. When not scraping up his hands on the inside of a PC case, you can invariably find Jason knee-deep in a PC game, engrossed in the latest console title, or at the movie theater.



Submit a Comment

Loading Comments...

Thanks for your registration, follow us on our social networks to keep up-to-date