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1.2.3.3. Converged Networks

Communication over the network is normally done through Ethernet, with storage traffic using a dedicated Fibre Channel SAN environment. It is common to have a dedicated network or serial link for system management, and perhaps even heartbeat[2]. As a result, a single server is typically on multiple networks.
Providing multiple connections on each server is expensive, bulky, and complex to manage. This gave rise to the need for a way to consolidate all connections into one. Fibre Channel over Ethernet (FCoE) and Internet SCSI (iSCSI) address this need.
FCoE

With FCoE, standard fibre channel commands and data packets are transported over a 10GbE physical infrastructure via a single converged network adapter (CNA). Standard TCP/IP ethernet traffic and fibre channel storage operations can be transported via the same link. FCoE uses one physical network interface card (and one cable) for multiple logical network/storage connections.

FCoE offers the following advantages:
Reduced number of connections
FCoE reduces the number of network connections to a server by half. You can still choose to have multiple connections for performance or availability; however, a single connection provides both storage and network connectivity. This is especially helpful for pizza box servers and blade servers, since they both have very limited space for components.
Lower cost
Reduced number of connections immediately means reduced number of cables, switches, and other networking equipment. Ethernet's history also features great economies of scale; the cost of networks drops dramatically as the number of devices in the market goes from millions to billions, as was seen in the decline in the price of 100Mb Ethernet and gigabit Ethernet devices.
Similarly, 10GbE will also become cheaper as more businesses adapt to its use. Also, as CNA hardware is integrated into a single chip, widespread use will also increase its volume in the market, which will result in a significant price drop over time.
iSCSI

Internet SCSI (iSCSI) is another type of converged network protocol; it is an alternative to FCoE. Like fibre channel, iSCSI provides block-level storage over a network. However, iSCSI does not provide a complete management environment. The main advantage of iSCSI over FCoE is that iSCSI provides much of the capability and flexibility of fibre channel, but at a lower cost.



[2] Heartbeat is the exchange of messages between systems to ensure that each system is still functioning. If a system "loses heartbeat" it is assumed to have failed and is shut down, with another system taking over for it.