5.10 Chapter Summary

Transceivers

• Transceivers are a critical component of the Fibre Channel transport.

• Vertical Cavity Surface Emitting Laser (VCSEL) transceivers provide high reliability for Fibre Channel applications.

• Serial ID support allows GBICs to provide inventory and diagnostic status but requires management software for reporting.

• Small form factor transceivers enable high port density on Fibre Channel products.

• SFP (small form factor pluggable) transceivers provide the flexibility of removable media for accommodating shortwave, longwave, and copper cabling.

Host Bus Adapters

• HBAs provide the interface between the host computer's bus architecture and the Fibre Channel network.

• HBA hardware, firmware, and device drivers fulfill Fibre Channel physical, link-level, framing, and upper-protocol requirements.

• For storage applications, the HBA maps Fibre Channel addressing to the SCSI bus/target/LUN identifier required by the operating system.

• The Common HBA API was developed by the SNIA to simplify management of multivendor HBA environments.

Fibre Channel RAID

• RAID is both a method for data distribution among multiple disks and a hardware implementation for disk arrays.

• RAID levels represent various techniques for improving performance and providing data security.

• Striping of data across multiple disks improves performance; mirroring of data provides redundancy. Parity algorithms can also be used to maximize speed and data integrity.

• Software RAID is performed by the host system; hardware RAID is usually performed by a controller within the disk array enclosure.

• A hardware RAID device can use parallel SCSI or Fibre Channel to interface between the disks and the RAID controller.

Fibre Channel JBODs

• JBODs are an economical means to provide Fibre Channel-attached storage.

• JBODs appear as loop segments and can be configured as single or redundant loops to disks.

• Disks within a JBOD can be addressed individually or can be assigned as sets for software RAID by a server.

• The overhead of software RAID across Fibre Channel may affect overall performance.

• Embedded loop switch-on-a-chip technology enhances the reliability of JBODs based on Fibre Channel disk drives.

Arbitrated Loop Hubs

• Loop hubs facilitate wiring configurations and enable hot insertion and removal of devices.

• Port bypass circuitry and status indicators simplify network changes and elementary diagnostics.

• Unmanaged hubs are economical but cannot provide protection against protocol-level events.

• Managed hubs can include loop integrity features based on protocol recognition circuitry.

Switching Hubs

• Switching hubs are based on a hybrid architecture that combines switched bandwidth with support for private loop devices.

• Switching hubs can allow multiple concurrent conversations on a single virtual loop.

Fabric Switches

• Fabric switches provide 100MBps or 200MBps per port and can support 8 to more than 128 ports.

• Support for fabric port types (F_Port, FL_Port, E_Port) is vendor-specific.

• Port buffering allows frames to be queued and reduces frame discard under congested conditions.

• Fabric switches can also support private loop devices and port or address zoning.

• Management of fabric switches can be provided via SNMP, Telnet, SES, and other protocols.

• Departmental fabric switches provide 8 to 32 ports.

• Larger deployments with departmental switches are best implemented using core director switches.

• Director-class fabric switches are characterized by high port count, redundant processors, routers, backplanes, and hot-swappable port cards.

Fibre Channel-to-SCSI Bridges

• Fibre Channel-to-SCSI bridges are transitional products that bring legacy SCSI disks and tape subsystems into a Fibre Channel SAN.

• Fibre Channel-to-SCSI bridges allow tape subsystems to be shared by multiple servers.

• Fibre Channel-to-SCSI bridges are not routers.

Fibre Channel Extension Products

• Native Fibre Channel extension normally cannot span beyond metropolitan distances.

• Dark fiber is unused fiber pairs already deployed in long haul optical cable runs.

• Dense wave division multiplexing (DWDM) supports multiple data streams on the same optical plant by assigning each stream to a separate wavelength (mode) of light.

• In stretched E_Port, switch-to-switch protocols are extended over distance and a single fabric is created.

• Fibre Channel over IP (FCIP) is a technique for encapsulating Fibre Channel frames in IP datagrams.

• FCIP devices require a fabric switch at each site.

• FCIP devices are deployed in pairs for each link to be served.

• A B_Port is a WAN bridge port connection and supports a subset of E_Port protocols.

• Creating autonomous regions requires manual administration of addresses to avoid Domain_ID duplication.