Making the case for FCIP and FCoE

Addressing corporate needs for metropolitan and local Fibre Channel (FC) connectivity over one common Ethernet network can mean lower energy usage and costs, and that's why many enterprise managers are looking at FC over IP (FCIP) and FC over Ethernet (FCoE) for their storage-to-network connectivity. These complementary Ethernet protocols let companies start down the road of consolidating on one network platform as opposed to maintaining separate FC and Ethernet networks.

But FCIP and FCoE require users to upgrade or replace some equipment, as well as address internal management issues.

The standardised FCIP protocol works by transmitting FC frames over TCP/IP, which can route FCIP FC frames locally or remotely over existing Ethernet switches and routers. The emerging FCoE standard also uses existing Ethernet switches and routers, but runs without TCP/IP at the Ethernet layer so it's not routable. That means it requires administrators to create point-to-point configurations, or zones, in Ethernet switches using the MAC addresses found on servers and storage network cards. This is similar to how admins create zones in FC SAN switches using the world wide name addresses presented by FC host bus adapters (HBAs).

The combination of FCIP's ability to route data remotely while FCoE keeps data local on the same Ethernet network makes these protocols particularly desirable for companies looking to consolidate to and manage one common network infrastructure. Still, it may be difficult to manage and the range of options can be confusing for customers.

Before most companies can entertain the idea of running both of these protocols over the same Ethernet connection, they'll want to upgrade from 1Gb Ethernet (GbE) to 10GbE to prevent the possibility of any network bottlenecks. Claudio DeSanti, technical leader in advanced architecture and research at Cisco Systems, recommends firms have a level of assurance that FC will work as well over Ethernet as it does in their current FC SANs. To do that, they should deploy a 10GbE network infrastructure.

A 10GbE infrastructure provides some distinctive benefits over FC. For instance, companies may no longer need to use both FC HBA and Ethernet NICs for storage and network connectivity; they can use 10GbE NICs for their storage and networking needs.

"FCoE is an evolutionary protocol helping to establish a shared Ethernet fabric for storage networks that can be interconnected with the FCIP protocol," says DeSanti.

Companies looking to transition to FCIP and FCoE will need to upgrade or replace existing Ethernet switches and NICs. Mike Krause, fellow engineer at Hewlett-Packard, says Ethernet switches and NICs will need to support 10Gb while Ethernet switches will need to understand how FC frames are transmitted over the network so they can create zones and do storage provisioning.

Krause expects companies will initially designate each 10Gb NIC card in servers for a single use--one card for data and the other for storage--and run FCIP and FCoE over the 10Gb NICs dedicated to storage. Companies would use FCoE for local storage traffic because it doesn't create TCP/IP overhead, while FCIP is a better fit for companies that need to route and encrypt data over the wire. "The best place to do encryption is with FCIP because it can use IPsec," says Krause.

Because data and storage networking are handled by different groups in an organisation, new protocols like FCIP and FCoE (that can run over the same Ethernet) will need to bring these two groups together. "During the convergence of IP networks and storage networks," says Krause, "there will be challenges with management tools and combined departments."