What does this have to do with fiber optics? Ethernet standards for fiber optic media have been published for decades. The earliest communicated at 10 megabits per second, like the wired Ethernet of its time, but it was expensive and saw only niche use. Fast Ethernet (100Base-T) on "Cat 5" copper wires is the kind of Ethernet that most people have seen. Fiber standards for that speed are also available (100Base-FX), and were also used in niches, though FDDI got there first and saw more use at on fiber at 100 megabits than 100Base-FX.
A major innovation in Fast Ethernet opened the floodgates. Full-duplex Ethernet eliminates all restrictions on the total distance that an Ethernet network can cover. Old Ethernet required that the network be smaller than a few thousand meters, so that packet collisions could be reliably detected. There are no collisions in full-duplex Ethernet. Distances are still limited, but only by the physical properties of the medium, such as twisted pairs or fibers, and these can be extended by adding switches (which also act as connection points). Once the distance limits of the old Ethernet protocol were eliminated, it became possible to use Ethernet at the farthest limits of fiber optic technologies, which can send signals reliably for many dozens of kilometers. Suddenly, cheap and compatible Ethernet gear could be used to build networks the size of a city, or larger.
The creation of Gigabit Ethernet (by Granite Systems and others) made Ethernet not just an available technology for wide area networks, but a compelling one. The only things that ran at similar speeds, like SONET gear, cost upwards of US$30,000 per node and are full of crazy complexities. Gigabit Ethernet gear can now be had less than US$500 per node, and it just plugs in to your existing Ethernet network. And 10-gigabit Ethernet gear is also readily available, with 40-gigabit gear available at the high end.
Gigabit Ethernet can use a variety of kinds of fibers, of widely varying cost, so gigabit fiber equipment is designed around an industry standard called "SFP" (Small Form Factor Pluggable) modules, which are about the size of a pack of gum. The standard is defined by a published "SFP Multi-Source Agreement" that specifies the physical dimensions, connectors, and signalling so that many vendors can build compatible products. Products such as routers or network interface cards provide one or more SFP slots, into which the user can plug an SFP module appropriate for that connection. The fiber itself plugs into a connector on the SFP module. Many dozens of kinds of modules are available, for use with different types of fiber, or for different wavelengths within a fiber, or for communication over shorter or longer distances. As with all Ethernet gear, the customer can mix and match components to meet their needs and desires as they build their network, and add new pieces from different vendors as their network expands.
Well, almost. Some vendors are trying to prevent their customers from making their own choices in the Ethernet market.
Cisco, the leading vendor of Ethernet switching and routing gear, has slipped a proprietary gotcha into the fiber optic slots in their switches. Cisco equipment won't accept "just any vendor's" compatible SFPs. The firmware in the switch checks the identifying data in the SFP's internal Flash memory, and if it isn't built by Cisco, the switch refuses to enable that slot. This practice has been taken up by some other vendors as well. Other vendors do not do it.
The obvious way to stop this practice is for customers to refuse to buy equipment that does it. Of course, the vendors do not advertise it - the customer only finds out when they discover that their "industry standard" component is deliberately refusing to talk to another "industry-standard" component. By that time, it's often too late to throw the entire thing back at the vendor and find a different vendor. This disreputable lock-in technique has only seen limited discussion on the 'net. Thus this article.
The technology used with these switches and modules will work with other vendors' since it is designed to work for enterprise use, but I suggest you also check the size of your slot from your switch and check if our module fits.
If it does, that will be great. However, we do not guarantee that it will work with other vendors' device. Once it is plugged to other vendors' device, we cant give any technical support for that."
Jennifer S. Doria
Linksys - A Division of Cisco Systems, Inc
Senior Product Support Specialist
(sent March 20, 2005)
"As long as the SFPs are SFP MSA compliance with SFF-8472, they will work. However, they will not have juniper P/N and serial (in CLI 'show chassis hardware'), and therefore not get support."
Error Message C4K_CHASSIS-3-SFPINTEGRITYCHECKFAILED:SFP integrity
check on port [char] failed: bad key
(same explanation and recommended action)
Error Message C4K_CHASSIS-3-SFPSERIALINTEGRITYCHECKFAILED:SFPs on
ports [char] and [char] have duplicate serial numbers
Explanation: Only Cisco-qualified Small Form-factor Pluggables (SFPs) are supported. Other SFPs place the associated port in the faulty status. All SFPs must have a unique serial number. If this message appears you likely have a cloned SFP SEEPROM.
Recommended Action: Replace the SFP with an SFP that Cisco supports.
If you install a mini-GBIC not certified by Extreme Networks into a switch and insert a cable to bring up the link, the port status LED remains "off" and an error specifying the use of a non-Extreme Networks-certified mini-GBIC is sent to the syslog. To view the syslog and to determine why the link is down, use the "show log" command. To correct this problem, install an Extreme Networks-certified mini-GBIC, available from Extreme Networks, into the mini-GBIC slot. ...
If you see an amber blinking mini-GBIC port status LED, the mini-GBIC installed in your switch or module is not approved, supported, or certified by Extreme Networks. To correct this problem, install an Extreme Networks-certified mini-GBIC.
Rumor is that Extreme followed Cisco's lead for a while, but extreme customer unhappiness caused them to change back to full compatibility in their newer products. They have not, however, released firmware upgrades that remove this restriction from their older products. This leaves a mix of lock-in and unrestricted products with the Extreme brand. Buyer Beware!
The following list of approved SFP transceivers is correct at the time of publication:
To access the latest list of approved SFP transceivers for the Switch on the 3Com Corporation World Wide Web site, enter this URL into your internet browser:
A fiber cable is connected but the Module Active LED does not light. Check that: ...
A 3Com SFP module is being used. Refer to "Approved SFP Transceivers" on page 14 for details.
Avoid 3Com switches. If your generic SFP fails to work in an existing 3Com switch, consider the savings you'll get from replacing that switch with one that's truly plug-compatible with your inexpensive SFPs.
This message appeared in an HP procurve's event log:
W 02/02/10 09:25:37 FFI: port 21 Not a ProCurve transceiver. Please go to: www.hp.com/rnd/device_help/2_inform for more info.
To resolve the issue, their weasel-worded "support" page suggests replacing the deliberately excluded "counterfeit" mini-gbic with their own brand:
This 10-gigabit PCI Express Ethernet adapter comes with lockin, according to its support site: "Other brands of SFP+ optical modules will not work with the Intel Ethernet Server Adapter X520 Series." As usual, the product literature provides no notice of this deliberate anticompetitive restriction. Hey, isn't Intel a monopoly, prohibited from anticompetitive practices like this?
As fiber-optic Ethernet grows out of its niche into a huge market, customers can keep Ethernet a fully "plug-compatible" system if they exercise a little care in their choice of vendors. Be sure to design your network so that gear which deliberately violates compatibility is excluded from your network. The people who have to maintain and improve your network in the future will thank you -- and you'll be standing in solidarity with every other intelligent customer.