This document is the result of the work carried out during our training course with the company
France Telecom R&D, in the LSD unit of research of the SDE laboratory, within of the project STORM
initiated by this laboratory. The principal aim of this project is the study and the evaluation of a service for the
interconnection storage networks through a same network in order to reuse the existing network
infrastructures.
The technical shutter of this project to which we were associated has the role to study and test the
existing technical solutions which on the one hand would fulfil the requirements of the market and on the
other hand would allow France Telecom to penetrate this market which remains hard for the operators. Our
intervention initially related to the theoretical aspect of the storage networks which begin with the study from
various architectures from networks from storage which are the NAS and the SAN. In the NAS architecture,
the systems of storage are connected on the company existing networks such as Ethernet, FDDI and ATM,
while the SAN is a network independent dedicated to the data storage and separated from the principal
network of the company. The SAN thus offers flexibility and an evolution in the resource allocation dedicated
to storage. Taking into account its advantages, the SAN is the most adopted architecture and our work was
based on the study of various technologies of this architecture. Fibre Channel protocol is the most used
technology SAN. Developed and standardized by INCITS and ANSI, Fibre Channel has five layers of
numbered protocols from 0 to 4. Layer FC-2 of Fibre Channel is most important because it is in charge of the
control of flow, logical and physical addressing and of the routing. This layer is equivalent layers 2, 3 and 4 of
the OSI. The type of control of flow used by Fibre of Channel is on the basis of credit.
This process of granting of credit is precisely one of the weaknesses of this protocol because the number of
credits increases with the distance which separates the equipments from the network. Many of other
mechanisms such as the general reconfiguration of FC network in the event of modification as well as the
limit of the distance of the interconnection make of this protocol a technology for small networks because its
administration and its management remain very tiresome.
The interconnection of the storage networks through Internet network becoming a real need taking
into account its advantages in term for safety and availability, the new protocols of storage called SoIP
(Storage over IP) will be snuffed. Thus we studied the functionalities of these protocols which are FCIP, iFCP
and iSCSI, developed all by l’IETF. All these protocols are based on existing network FC but propose
mechanisms which make it possible to avoid the problems of FC protocol by ensuring the interconnection of
FC networks through an IP network. FCIP protocol integrate like data the Fibre Channel frames
encapsulated in the TCP segments in order to retransmit them on the IP network. With this protocol, all FC
messages circulate on IP link, which can involve a saturation of this link. FCIP network has the same
characteristics as FC network because the services of FC networks remain intact and are re-used. The iFCP
protocol just like FCIP integrates FC frames encapsulated in TCP segments but, it simulates various FC
services and proposes panoply of mechanisms which make it possible to be been free from all the problems
of FC networks. Thus with its process of translation of address, the iFCP networks are not limited to 239
switches like are FC and FCIP networks. Moreover with this protocol, one avoids the reconfiguration of the
entire network in the event of incidents and each FC network is autonomous and independent on the Fibre
Channel level. The iSCSI protocol, contrary to the others, directly integrates SCSI commands encapsulated
in TCP segments, which enables him to be a little more powerful than the others. This technology can
provide iSCSI interfaces to the storage customers and servers alternatively to those of Fibre Channel, which
makes it possible this equipment to behave like infrastructures IP and to be connected directly to IP Network
without an unspecified gateway like does it iFCP and FCIP.
The second aspect of our work concerned the realization of tests according to various theoretical
studies carried out. Indeed these tests are worked out and carried out according to the planning stopped in
the contract of partnership between France Telecom and the manufacturers who propose the switches to be
tested. Thus, the manufacturers like ALCATEL/CNT, McDATA and Cisco had their gateways tested.
ALCATEL/CNT and Cisco proposed a FCIP switches while McDATA provided iFCP switches that they are
the only ones to currently implement.
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