Hardware Details - more
Figure 3 shows the layout of the Balance 30's main board. Cooling is passive, thus the Balance 30 runs silently. The CPU and Ethernet switch are an integrated System-on-Chip (Sock) circuit from Micrel, part number KSZ8695P, using Micrel's 166 MHz ARM9 processor along with a five-port Ethernet switch. Although the chip says it is a five-port Ethernet switch, the Balance 30 only has four physical LAN ports. 10/100 Ethernet controllers are Realtek RTL8139D chips.
Figure 3: Internal view of the Balance 30
The Balance 30 has a healthy amount of memory. In addition
256 32 MB SDRAM (chip part number V54C3256164VDI7I), the device uses
dual flash memory for boot images. Firmware files can be loaded to one of the
two 64 8 MB flash chips (chip part number S29GL064A90TFIR4) and either can be
selected as the boot source, as illustrated in Figure 4. This provides the
ability to test a new firmware release and a nice fallback in the event the new
firmware causes issues.
Figure 4: Selecting the flash chip to use as a boot source
Network - WAN
Each of the three WAN interfaces supports Static or DHCP addressing using Ethernet, PPPoE, or GRE configurations. A simple DHCP connection would likely be used for cable Internet connections, with PPPoE often used for DSL Internet connections. Further, Dynamic DNS to changeip.com, dyndns.org, and no-ip.org is supported on each WAN interface.
GRE is an interesting WAN option. Generic Routing Encapsulation is a WAN option often used with a service provider supplied VPN tunnel. Figure 5 shows the simple menu for selecting a WAN interface, which is the starting point to get into a specific interface's configuration mode.
Figure 5: Selecting a WAN interface
I connected my Balance 30 using Static and DHCP services, as well as to an authenticated PPPoE service, all successfully. Each of the WAN interfaces can be configured as Always-on and used in a Load Balancing configuration, or as a Backup to then be used in the event an Always-on connection fails.
There are three Load Balancing Policy options as shown in Figure 6. The High Application Compatibility mode will route all traffic from a PC to a single WAN interface. In this mode, all the traffic from a PC will route to a single WAN connection. Load balancing is then achieved by distributing the PCs over different WAN connections. For example, in a network with 10 PCs and two equal WAN connections, five PCs would use the first WAN connection, and the other five PCs would use the second WAN connection.
The Normal Application Compatibility mode will route traffic from a PC to a specific destination over a specific WAN interface. Load balancing is subsequently achieved by spreading out the destinations over different WAN connections. For example, PC 1's connection to one web site will flow over WAN1, while PC 1's connection to a second web site will flow over WAN2. Each PC's traffic to various destinations will be similarly distributed over the WAN interfaces. This is the default mode and allows for the greatest level of load balancing.
Figure 6: Load Balancing Policy options
Custom Load Balancing options also exist, enabling mapping specific applications to specific WAN interfaces. More specifically, traffic flows defined by source and destination IP addresses, protocols, and/or port numbers can be distributed over multiple interfaces using one of four load balancing algorithms: Weighted, Persistent, Enforced, and Priority.
The Weighted algorithm allows for assigning a weight to each WAN interface. Traffic percentages will then be allocated to each interface based on its relative weight. The Persistent algorithm is used to apply High Application Compatibility to some applications and/or Normal Application Compatibility to others. The Enforced algorithm is used to map specific traffic types directly to a specific WAN interface, and the Priority algorithm directs all traffic to the top priority WAN interface first, then to the second priority WAN interface, and then to the third.
For simple fail-over, a WAN connection can be configured as Backup. In this case, it will only be used when other WAN connections fail. With three WAN interfaces, the option exists to configure WAN1 as Always-on, WAN2 as Backup Group1 and WAN3 as Backup Group2. This configuration would tell the Balance 30 to fail-over from WAN1 to WAN2 to WAN3, in that order.
In multiple tests of Backup Mode, it took approximately 55–60 seconds before I could successfully surf the Internet after simulating a failure by disconnecting an active WAN connection. The Balance 30 acts as a DNS proxy, so my laptop on the router's LAN side didn't have to change DNS IP addresses when the Balance 30 switched over to a different WAN connection.