Fibre Channel switch (FC switch)
What is a Fibre Channel switch?
A Fibre Channel (FC) switch is a networking device that's compatible with the FC protocol and designed for use in a dedicated storage area network (SAN). An FC switch inspects a data packet header, determines the computing devices of origin and destination, and then forwards the packet to the intended system.
FC switches are used to connect computer data storage to servers. They're typically added by SAN administrators as an organization's data center storage needs increase. These switches are designed for high performance, low latency, high availability and lossless data transmission. Director-class FC switches can add capabilities, such as encryption and zoning, to disable unwanted traffic.
There are different types of FC switches, including modular director, fixed-port or semi-modular. FC switches can be combined to create large SAN fabrics that interconnect thousands of servers and storage ports.
How a Fibre Channel switch works
Fibre Channel networks are a switched network topology that interconnects FC devices using FC switches. FC networks are specifically designed to connect hosts or servers to storage devices.
FC supports point-to-point connections, where a server's FC host bus adapter is directly connected to a storage device, allowing the host to access the attached storage directly. Although a point-to-point architecture might be desirable in certain situations, the architecture doesn't scale well because every host requires a direct connection to any storage device that it could conceivably need to access.
An FC switch addresses this problem by acting as an intermediary between servers and storage. Servers are provided with a physical link to an FC switch rather than being attached directly to storage devices. Likewise, storage devices are also attached to the switch. When a server needs to access a storage device, the FC switch directs the request to the appropriate storage device.
Benefits of a Fibre Channel switch
FC switches offer the following benefits:
- Don't require direct connections. FC switches reduce complexity because they don't require every server to have a dedicated connection to every storage array.
- Greater transmission speed. In some cases, FC switches can provide greater bandwidth than a single FC connection. This is because FC switches can handle parallel traffic streams, so the total bandwidth provided by an FC switch is usually greater than what any one high-speed port can deliver.
Fibre Channel switches vs. Ethernet switches
Ethernet and FC switches differ in their use cases. While FC switches are primarily used for SANs, Ethernet switches are mostly used in local area networks. In addition, Ethernet networks can be used for general-purpose network communications -- such as for PCs, tablets and internet of things devices -- while FC switches are used only for connecting servers to storage arrays. They aren't used for general purposes, nor do FC devices require an Internet Protocol address.
Another important difference is that FC is a lossless protocol, compared to an Ethernet network where packet loss is possible. FC also ensures that packets arrive in the order in which they were transmitted, whereas Ethernet networks allow packets to arrive in a different order from the way they were transmitted.
Learn how FC compares to other network protocols, such as Internet Small Computer Interface, Fibre Channel over Ethernet, HTTP and non-volatile memory express over fabric.
