Vitesse VSC738x: GbE breaks $5/port

I know very little about ABS, but I just recently purchased some of their 5-8 port unmanaged GbE switches for about $2-4/port after rebate (around $6/port before rebate) from NewEgg.COM (ABS NW-110-5P 5-port, ABS NW-111-8P product pages). Now I would never use these switches in a place of business, or at least not outside a segmented lab, but they do provide a nice solution for periodic home usage (although they would be questionable for larger LAN Party usage).

The specifications (marketing?) on the box are as follows:

• MDI-X: "N-Way Switch," " Easy set up with Auto MDIX (Auto Cross Over)"
• 802.3x: "IEEE802.3x flow control in full duplex and back pressure in half duplex"
• Buffer: "Built-in 112K" (5p), "144K" (8p) "Bytes Buffer Memory"
• Jumbo: "Supports Jumbo Frames (Up to 9KB) on all speeds"
• AC in: "Built-in universal AC input: 100~140Vac at 50/60Hz"

At first, these look like outstanding specifications for a switch that is under $6/port and as low as $2/port after rebate. Especially never seen at a sub-$10/port is the universal AC in -- no external AC/DC adapter -- very nice (and virtually universal for the world)! Unfortunately, outside of the AC in, real-world experience proved otherwise with this unit.

I'm still in the middle of testing but it is clear neither the 5-port nor the 8-port do auto MDI-X -- at least at 100Mbps. I had to use a cross-over cable to uplink to another switch. Now that could be due to the fact that my main switch (SMC SMCGS8 8-port -- possible the exact same ASIC) was another auto MDI-X (and another desktop switch unit at that, although I did verify auto MDI-X does work), so auto-negotiation between the two could be to blame (or the expectation of GbE when only 2-pair/4-conductor is used).

Furthermore, it's clear that things like Jumbo Frames are only supported when all nodes are matching. I did not note any IEEE 802.1q VLAN support, which is virtually required to run different frame sizes (let alone routing or integrated layer-3 switching for wire-speed). People (see NewEgg.COM reviews) have experienced issues with Jumbo frames as well. Makes me wonder if 802.3x flow control is not a reality either -- as 802.3x is probably the most essential requirement of all GbE NICs and switches (the old issue of pre-switch collision domains are tame in comparison, long story).

So what's behind these units? In a nutshell, other than the 100~240Vac @ 0.1A that converts to 3.3V @ 2.0A (6.6W max) internally, they are reference ASIC Vitesse VSC7385 (5p) and Vitesse VSC7388 (8p) units. The VSC7388 is quite a bit bigger BGA package than the VSC7385 -- probably because of the added PHY logic and shielding, but they both run off the same model 3.3V @ 2A supply. One thing I did note is that the PCBs, LEDs and other components are of higher quality than typical, low-cost DLink and Linksys devices I've opened. DLink and Linksys really have some shabby manufacturing and LED/plastic quality in my experience, and ABS seems to be at least a small step up.

Now according to the Vitesse datasheets, they have the following specifications beyond the above:

• ASIC @ 25MHz w/8051 (8-bit) microcontroller w/option to use off-chip microcontroller
• 9.6KB Jumbo Frames
  
• 4K VLANs (IEEE 802.1q), LACP (IEEE 802.3ad), STP (IEEE 802.1d) and others

Now this datasheet clearly indicates a flexible design for using an external ARM/MIPS microcontroller. So I have to assume to get IEEE 802.1d, 802.1q, 802.3ad, etc... support -- possible Jumbo Frames as well (with 802.1q) -- is only an option when such "management" is available. I really don't see the 8051 8-bit microcontroller ASIC core doing much other than handling 8-bit octets for MAC addressing filtering, maybe auto MDI-X/duplex (which even I had issues with). I didn't see any mention of explicit auto MDI-X support, although that might be part of the RGMII/GMII PHY chips and another datasheet.

I can't recommend these switches for anything but casual use where reliability must not be a certainty. I still think it's well worth the cost to go with an entry-level NetGear FSM/GSM 73xx series layer-3 switch for $300+ when you have a dozen or more nodes in a production office. At least as your backbone when you're going to use 5-8 port desktop switches between 4-6 cubes. In fact, the $300 FSM7328 makes a great entry-level solution with its full management, layer-3 wire speed support (and RIP v1/v2) and four (4) GbE ports which can be used as downlink ports to 5-8 port desktop switches and/or servers in the closet (and removes the need for an internal router). Even the OSPF-capable GSM7312 is approaching $600, which makes it $50 per [backbone] port, full layer-3 with >20GBps switch fabric and ideal for most 50-node offices -- especially when part of a multi-site. You can always downlink to desktop GbE for reduced port costs.