Ethernet Vs. Fibre Channel - Lenovo Flex System Fabric CN4093 Application Manual

Ethernet vs. Fibre Channel

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CN4093 Application Guide for N/OS 8.2
As a converged switch, the CN4093 10Gb Converged Scalable Switch provides
simultaneous support of Ethernet and Fibre Channel networks.
Ethernet is ubiquitous in modern networks. It is generally quick, easy, and
inexpensive to implement. Ethernet is also flexible and dynamic by nature. Devices
join and leave a well‐designed Ethernet network with little impact beyond their
individual function. Because flux is the norm, Ethernet is classified as a ʺbest effortʺ
delivery protocol. This means that some loss of packets is acceptable, and that with
multiple routes often available, packets in a stream may arrive at their destination
out of sequence. Ethernet devices are expected to re‐request and resend lost
packets, and reassemble data in the proper order at the destination.
The Fibre Channel protocol adheres to a very different philosophy. Fibre Channel
is most popular in storage networks end‐to‐end stability, reliability, and security
are emphasized in favor over low cost and dynamic scalability. In Fibre Channel
networks, the connecting ports must be fully authorized to communicate with their
well‐defined neighbors. Bandwidth for properly connected devices is tuned to
avoid loss due to congestion. Also, routes for traffic are converged in advance,
ensuring that only one route is used by any given traffic stream so that packets
arrive in their expected sequence.
Ethernet and Fibre Channel networks are coming into contact with each other
more frequently in modern networks. In some cases, legacy Fibre Channel devices
are connected via Ethernet networks using Converged Enhanced Ethernet (CEE), a
collection of recent Ethernet features designed to satisfy Fibre Channel delivery
expectations. Although not the focus of this chapter, the CN4093 supports CEE and
Fibre Channel over Ethernet (FCoE). For details, see "FCoE and CEE" on page
Another approach is to use converged switches such as the CN4093 to support
direct connection to both Ethernet and Fibre Channel networks. This allows a "best
of both worlds" approach, using ubiquitous Ethernet networks for regular traffic,
and full connection to Fibre Channel networks for lossless applications and the
legacy architecture of established Storage Area Networks.
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