So, you already have a router in your network, and rather than take on the expense of another piece of equipment, you want to double-up on functionality by implementing your bandwidth control within your router. While this is sound logic and may be your best decision, as always, there are some other factors to consider.
Here are a few things to think about:
1. Routers are optimized to move packets from one network to another with utmost efficiency. To do this function, there is often minimal introspection of the data, meaning the router does one table look-up and sends the data on its way. However, as soon as you start doing some form of bandwidth control, your router now must perform a higher-level of analysis on the data. Additional analysis can overwhelm a router’s CPU without warning. Implementing non-routing features, such as protocol sniffing, can create conditions that are much more complex than the original router mission. For simple rate limiting there should be no problem, but if you get into more complex bandwidth control, you can overwhelm the processing power that your router was designed for.
2. The more complex the system, the more likely it is to lock up. For example, that old analog desktop phone set probably never once crashed. It was a simple device and hence extremely reliable. On the other hand, when you load up an IP phone on your Windows PC, you will reduce reliability even though the function is the same as the old phone system. The problem is that your Windows PC is an unreliable platform. It runs out of memory and buggy applications lock it up.
This is not news to a Windows PC owner, but the complexity of a mission will have the same effect on your once-reliable router. So, when you start loading up your router with additional missions, it is increasingly more likely that it will become unstable and lock up. Worse yet, you might cause a subtle network problem (intermittent slowness, etc.) that is less likely to be identified and fixed. When you combine a bandwidth controller/router/firewall together, it can become nearly impossible to isolate problems.
3. Routing with TOS bits? Setting priority on your router generally only works when you control both ends of the link. This isn’t always an option with some technology. However, products such as the NetEqualizer can supply priority for VoIP in both directions on your Internet link.
4. A stand-alone bandwidth controller can be moved around your network or easily removed without affecting routing. This is possible because a bandwidth controller is generally not a routable device but rather a transparent bridge. Rearranging your network setup may not be an option, or simply becomes much more difficult, when using your router for other functions, including bandwidth control.
These four points don’t necessarily mean using a router for bandwidth control isn’t the right option for you. However, as is the case when setting up any network, the right choice ultimately depends on your individual needs. Taking these points into consideration should make your final decision on routing and bandwidth control a little easier.