Media Options for 10 Gigabit Ethernet

Despite strong growth in 10GbE deployments, 10GbE has yet to achieve mass market Data Center adoption, due to a number of limitations, primarily around cost, power consumption, and cabling options. The following section outlines several of these limitations in greater detail and discusses how the current generation of 10GBASE-T technologies removes them going forward.

10GBASE-CX4

10GBASE-CX4 was an early favorite for 10 GbE deployments, but its adoption was limited by bulky and expensive cables and limited reach of 15 meters. The large size of the CX4 connector, when compared to other interface options, prohibited higher switch port densities, specifically with 1RU top of rack switches and modular switch chassis. Moreover, pathways and spaces were not sufficient to handle the larger cables.

SFP+ Transceiver

SFP+'s support for both fiber optic cables and DAC make it a more flexible solution than CX4. SFP+ connectors are smaller than CX4 connectors and offer comparable port densities to their GbE counterparts. SFP+ DAC is the leading 10GbE interface today, but its limitations in reach and cost will prevent this media from becoming the de facto cabling and interface technology for 10GbE.

10GBASE-SR (SFP+ Fiber)

Cabling with Fiber is great for latency and distance (up to 300 meters). Fiber cabling coupled with optical transceivers offers the best power consumption footprint, however it is more expensive than other 10GbE media types; optical transceivers can add up to 30-40% to server, switch, and storage interface costs. The fiber electronics can be four to five times more expensive than their copper counterparts, meaning that ongoing active maintenance, typically based on original equipment purchase price, is also more expensive. This drives up both the acquisition costs as well as the ongoing annual maintenance contracts. Further, the vast majority of SFP+ connections are sold as add-in server adapters, as opposed to 10GBASE-T connections, which are now integrated on server motherboards. This add-in model adds cost and maintenance overhead.

10GBASE-SFP+ DAC

DAC cable is a copper 10 Gigabit Ethernet cable which comes in either an active or passive Twinax (twinaxial) cable assembly and connects directly into an SFP+ housing. The active Twinax cable has active electronic components in the SFP+ housing to improve the signal quality; the passive Twinax cable is just a straight "wire" and contains no active components. The adoption rate of DAC for LAN on Motherboard (LOM) will be low, since it does not have the flexibility and reach of 10GBASE-T. With top of rack deployments, it is very difficult to use all the switch ports purchased due the generally lower number of server adapter ports and the limited reach of the cables. These unused ports carry an initial cost outlay and require power (even in idle mode) and maintenance costs, making them expensive on an ongoing basis.

Meida Options for 10 Gigabit Ethernet

10GBASE-SR (SFP+ Fiber)

• OEM 10GBASE-SR SFP MMF multi-mode 850nm 300m transceiver for duplex optical data communications such as 10GBASE-SR and 10GBASE-SW
• Cisco SFP-10G-SR compatible 10G SR SFP+ 850nm Transceiver Module MMF
• Finisar FTLX8571D3BCV compatible 1000BASE-SX, 10GBASE-SR and 10GBASE-SW 850nm 300m Transceiver Module MMF
• HP JD092B X130 compatible 10GBASE-SR SFP+ 850nm 300m Transceiver Module
• Brocade 10G-SFPP-SR compatible 10GBASE-SR SFP+ 850nm 300m Transceiver Module

10GBASE-SFP+ DAC

• Cisco SFP-H10GB-CU1M, Up to 10.5G, 1m AWG30, passive copper
• Cisco SFP-H10GB-CU1-5M, Up to 10.5G, 1.5m; AWG30, passive copper
• Cisco SFP-H10GB-CU2M, Up to 10.5G, 2m; AWG30, passive copper
• Cisco SFP-H10GB-CU3M, Up to 10.5G, 3m; AWG30, passive copper
• Cisco SFP-H10GB-CU5M, Up to 10.5G, 5m; AWG24, passive copper
• Cisco SFP-10G-AOC1M, SFP+ AOC, fiber, 10G, 1m
• Cisco SFP-10G-AOC3M, SFP+ AOC, fiber, 10G, 3m

Compatibility Issues of Cisco Compatible SFP module

There are some compatibility issues that I have to solved when installing a Third Party Cisco Compatible SFP modules into the switches.

Q: I am trying to work out which Third Party Cisco Compatible SFP Transceiver might work in an Aerohive switch. Maybe somebody here already tried?

A: The answer is that most should work. Cisco normally buys their components from the more reputable brands like Agilent, and the best of my knowledge, most Cisco (if not all) SFPs should work just fine. For example, GLC-T module Cisco 1000BASE-T SFP, Cisco SFP-10G-SR, I can reach the Aerohive switch, and seems to be working well. So I suggest you not buy no-name SFPs that have no warranty, but in general any reputable brand should work fine.

Q: The 10G SFPs I ordered directly from Aerohive were manufactured by source photonics, so it looks like even the ones that are Aerohive branded are still Third Party optics?

A: Because this is exactly the same with all vendors of all networking equipment. Optics are manufactured elsewhere and simply branded. The APs are not physically constructed by Aerohive ether, those are by ODM companies like Senao. This is the same ones with most vendors. Because of commoditisation of parts, the key differentiator is today in the software and the spec that the ODM is asked to work to. Most people just purchase a few of the 'supported' optics to swap in when the need arises to open a support case. Actually it seems to be a method of extortion by various vendors when mixed with as much FUD stirring as they can manage. There are certainly low quality optics out there that don't work nicely or have high failure rates, but compatibility issues are nearly always deliberately imposed.

A quick correction, Cisco and other vendors actually do design and build their APs. The fact that ODMs manufacture them does not mean that they are just buying Cisco and other vendors APs off the shelf. Most APs use reference designs for the CPU etc, but to build a reliable AP, Cisco need to own the RF side and they do. They design their own radio modules.

Another Issue about SFP module compatibility:

I just received and installed an Aerohive SR2124P switch and I have installed a 10G SFP+ SR optic into the switch, but the media and type are showing "unknown" for the optic. Is that normal for the 10G optics to show in this way? Currently I do not have an 10gig Aerohive original SFP+. I have installed a 3rd party 10G SFP+, and the optic links, and passes traffic with no issue (even though it is not an Aerohive SFP+). Since it shows "unknown" in the switch, I was just curious to see if any Aerohive Original (which I believe is a Source Photonics optic) would show up differently in the machine. I have used both Aerohive and HP modules both 1gb and 10gbe SFP+ SR with no issues, literally just attach it in. If another brand, it's possible the GBIX is at fault. Has anyone ever tried it?

More FAQs about SFP module, please visit Fiber Opitc Transceiver Solutions.