The California Internet Service Provider’s LAB has elected to share some of our lab and field testing information with all. This first finding is that of the CPU platform dealing with preformance and troubles.
-
4% of troubles were do to faulty equipment, even brand new right out of the box. Many of the manufactures out there are have some real quality control issuses.
-
41% of lockups, reboots, interfaces going off line are caused by power supply troubles. Within this area, the largest offender was that of voltage fluctions. We found that if the voltage drops below 1 to 1.7 volts below the min. level of the on board regulators (ie RouterBoards, ITX, etc), the system will become unstable and lockup, drop an interface, reboot or go on and off line every few seconds. We also found that on most of these board, an impulse drop of only a few ms will cause this trouble.
-
55% of troubles; and this is the big one; is that our running out of CPU cycles inorder to complete the states tasks with in the MT RouterOS. Some of our findings are this; 1 NSTREME Channel running on an atheros card, no Firewall, NAT, etc, nothing but bridging requires a 233mhz x86 CPU to even begin to run; a 266mhz x86 CPU will run 99% of the time. 2 NSTREME Channels running on atheros cards requires a min of 700mhz x86.
If the CPU reaches 95% usage or above, your system will behave badly. This is not a Software Problem it is an implementation Problem. You can not put a Porsche sticker on a Volkswagon Bug and expect it to run in a Formula 1 Race!!! 
Adding Firewall Rules, NAT, Simple queues, etc to the mix takes up even more CPU cycles.
Bottom line: The RouterBoards are fantastic for use as CPE (Customer Equipment), Small Office Wireless systems. Point to Point Links, and small firewall appliances. They do not have enough CPU power to do much above that.
To go beyound this level you need CPU power!!!
Final Note: The use of Power over Ethernet has many problems. At lease the RouterBoards have an active regulator and therefore reduce the power fluction trouble greatly. The WRAP boards have a very poor regulator on them and therefore have much more trouble. When running POE, you must remember Ohm’s Law and the resistance of the wire per 100 foot. E=I/R (E voltage drop = I current in amps) / R the total resistance of the circuit) As the Current goes up (increase in CPU usage or activity on cards; etc) the Voltage Drop will increase, as the Current gose down the Voltage Drop will decrease. Thus the voltage is alwasy fluctuating on this line. Temp, humidity, etc will also effect the resistance of the line. Also do not forget the added resistance of the RJ-45 connectors. Moreover, most RJ-45 Connectors will change in resistance over time, humidity, temp, etc…
IF you are a member of CISPA (California Internet Service Providers) there is very detailed information on this available from the LAB. Also, there is a list of Boards tested and their results.