Some IT architects are apt to be indecisive when selecting Fibre Channel (FC) switches or Ethernet switches for their data center infrastructure. Or they may have invested in Fibre Channel networking before, but consider whether to stay with FC or make the move to Ethernet. This article will illustrate what Fibre Channel switch and Ethernet switch are, and make a detailed comparison between the two.
Fibre Channel (FC), designed for storage area networks (SANs), is a high-speed network technology used to connect computer data storage to servers, providing point-to-point, switched and loop interfaces to deliver in-order and lossless raw block data.
In the switched fabric topology that requires switches, all the devices are connected and communicated via switches. A Fibre Channel switch, namely, is a networking device that is compatible with the Fibre Channel Protocol (FCP), and features with high-performance, low-latency, and lossless-transmission in a Fibre Channel fabric. Known as one of the main components used in SANs, the Fibre Channel switch plays an important role in interconnecting multiple storage ports and servers.
Figure 1: The working scenario of FC switches
"Ethernet," this word is not unfamiliar to you compared with "Fibre Channel." The Institute of Electrical and Electronics Engineers (IEEE) defines Ethernet as protocol 802.3. Jargon aside, Ethernet refers to the technology of connecting computers and other devices via a protocol, which is most commonly used in wired local area networks (LANs).
When deploying an Ethernet network, Ethernet switches are indispensable certainly. Ethernet switches are the basic building blocks of networks, which bridge Ethernet devices together. Normally speaking, a LAN switch is likely to be an Ethernet-based switch with copper or optical interfaces, the ports number of which vary. The speed that the switches can support may be 1GbE, 25GbE, 40GbE, 100GbE or even higher.
Figure 2: The working scenario of Ethernet switches
As mentioned before, Fibre Channel switches are mainly used in SANs whilst Ethernet switches are mostly applied in LANs. This part will further illustrate the differences between these two switches in three main aspects: reliability, transmission speed, and cost.
Fibre Channel is considered a lossless protocol. Fibre Channel switches are lossless, while Ethernet switches may be at the risk of dropping a frame. For Fibre Channel switches, they can operate smoothly without dropping a single frame, and all the data frames are transmitted in order. That is because the FC switches will stop sending frames lest they are dropped when congesting to other devices. On the contrary, the Ethernet switches will just start dropping frames when congested, only relying on upper layers, TCP (Transmission Control Protocol), for example, to make sure everything keeps working.
The maximum data rate of the Fibre Channel switch at the very beginning is 1Gbps. Now it has evolved up to 128GFC, with 8GFC, 16GFC, and 32GFC versions available. The Ethernet switch transmission speed ranges from Fast Ethernet, Gigabit Ethernet, 10 Gigabit Ethernet to 40/100GbE. A majority of Fibre Channel networks these days are 8Gbps or 16Gbps, while most Ethernet installations are typically 1Gbps/10Gbps for home networks and 40Gbps/100Gbps for data center networks. Generally speaking, 8GFC networks run close to the effective rate as 10GbE, so the difference is nearly negligible. And 16GFC is pretty much faster than 10GbE. Performance is sometimes at least a tie. In a word, the practical transmission speed of each will be decided by the specific working environment.
Cost is evidently an important considering factor before selection. In most cases, Ethernet switches are much cheaper than Fibre Channel switches in view of pricing. However, Fibre Channel is mainly used in the data center storage environment, while Ethernet can be found in different kinds of networks: from small homes, big offices to large-scale data centers. We have to make an apples-to-apples comparison. For the employment of a data center, 8Gbps FC is generally less expensive than 10Gbps Ethernet. And 16GFC costs about the same as 10GbE. When it comes to enterprises, many already have invested large amounts of time and effort for their Fibre Channel networks, switch to Ethernet means a start-over with extra expenses. Ethernet isn't always a price-wise option.
Besides, the maintenance fee is also a factor that should be considered. In large IT systems, if an Ethernet switch breaks down, most admins can deal with it. However, when there is something wrong with the Fibre Channel switches, they need to turn to manufacturers, instead.
Many Ethernet proponents may argue that Fibre Channel is dying on account of Ethernet's high-performance, simplicity, and popularity in most scenarios. For new network implementations, if you've not invested in FC, Ethernet networking is considered a good way to go. However, as the only long-term de facto solution for enterprise-level data storage, insisting on Fibre Channel is more persuasive. An alternative form of Fibre Channel called Fibre Channel over Ethernet (FCoE) was invented to lower the cost of FC solutions by eliminating the need to purchase HBA (host bus adapter). Sticking to Fibre Channel, jumping ship for Ethernet, or picking FCoE solution all depend on your needs.