Setup and Feature Tour

The PowerConnect 2708 ships configured as an unmanaged switch. In many environments, additional setup such as configuring VLANs and changing default QOS settings may be unnecessary, so the defaults may be adequate. The user guide supplied on CD details all of the defaults, and you might decide to boot in unmanaged mode and start connecting devices. The boot process takes only about 30 seconds.

Should you decide that you want to manage the switch and poke around in the user interface, you’ll have to enable management mode by pressing the Management mode pin reset button on the front panel. After a reboot, the management LED will indicate that the switch is manageable.

Though the 2708 has a built-in DHCP client, the default IP address is 192.168.2.1. You’ll need to temporarily connect a computer on the 192.168.2.0/24 net to initially “talk” to the switch, and most likely change its address to match your local network.

I discovered a nice setup feature while configuring the switch. When I changed the setting to DHCP while I was configured on the 192.168.2.0/24 net, the switch retrieved an IP address from my DHCP server and displayed it for me. Only after I accepted the address, (and made note of it), did the 2708 apply the new address. Many other switches don’t retrieve an address from your DHCP server before you “save” the configuration, so after reboot, you’re left wondering what the new address of the switch is.

Once logged onto the web-based management console, you’ll find an easy-to-use menu system. Menu choices are displayed vertically along the left side of the screen. The menu system is flat and only one layer deep, so you won’t have to search through multiple levels of menus to find what you’re looking for.

Each page has a “Print” button so that you can document your switch, as well as a refresh button. For those who choose to ignore the comprehensive 84-page user manual, brief context-sensitive help (Figure 1) is available for each menu in a popup window.

Figure 1: DSCP to Queue configuration showing help in pop-up window

Check out the slideshow for a detailed admin interface tour of the PowerConnect 2708.

I’ve updated the comparative features table here, so I won’t belabor those details. Still, I’d like to point out some of the highlights of the 2708.

The 2708 supports up to six Link Aggregate Groups (LAGs) with up to four ports per LAG. A LAG allows using multiple Ethernet ports and cables in parallel to improve bandwidth and to provide redundancy. This is often a cost effective solution in server backbone applications when performance beyond 1Gbps full duplex is required and budgets don't permit upgrading to 10 Gbps equipment.

When a port is added to an LAG, it acquires the properties of the LAG. You configure both port and LAG parameters on the interface configuration menu shown below (Figure 2). You can enable or disable each port or LAG, set auto negotiation, change advertisements, and enable/disable backpressure and flow control. Below the interface configuration, you’ll find the status of each port—information that I would have expected to see on the Switch Status page.

Figure 2: Dell PowerConnect 2708 Interface Configuration

The PowerConnect has four hardware priority queues. You can map each of the eight CoS to one of the four queues. Similarly, you can also map egress queues for each of the 64 DSCP values. Under CoS settings, you can choose either CoS (802.1P) tagged packets, DSCP or none. You also have the choice of Strict priority or Weighed Round Robin (WRR). 

The 2708 has a local user database for authentication. You can create additional users and provide them with either Read only or read/write privileges. There is a file update feature to allow you to update the firmware, but since it’s based on TFTP rather than a simple browser-based dialogue box, SOHO users might find updating firmware somewhat intimidating. I didn’t find a dialogue to save configuration settings, so you just have to hope you won’t wipe out your settings when you update the firmware.

I also liked several other features. The 2708 supports port mirroring for up to four ports. For each mirrored port, you can choose TX, RX or TX and RX traffic. It also support per port storm control. Enabled by default, for each port you can set a broadcast rate threshold for broadcast only, multicast and broadcast, or unknown unicast, multicast, and broadcast. 

You can view RMON statistics for each port or LAG. In addition to sent and received statistics, you can see error counters as well as a distribution of packet sizes. 

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