SteelHead™ Deployment Guide - Protocols : CIFS Optimization
CIFS Optimization
This chapter describes the Common Internet File System (CIFS) protocol optimization module on the SteelHead. This chapter includes the following sections:
  • Overview of CIFS Protocol
  • RiOS CIFS Optimization Techniques
  • CIFS, also referred to as the Server Message Block (SMB) protocol, has been in existence since the early 1990s. The protocol provides shared access to files and printers, along with other communication between hosts on a network, including an authenticated Inter-Process Communication (IPC) mechanism. It is one of the most common protocols used for network file access by Microsoft operating systems.
    The protocol originated as SMB and was created by combined work from IBM and Microsoft. SMB was initially designed to run on top of NetBIOS/NETBEUI but has run directly on top of TCP since the Microsoft Windows 2000 version. SMB was primarily a LAN-based protocol, which accounts for some of the challenges you see when it is used across WAN links. The rename and relaunch from SMB to CIFS occurred in 1996, which was the same time that Sun Microsystems announced WebNFS.
    Although CIFS is known as the generic name for the protocol, technical discussions and documents continue to use the term SMB. Since the initial release of SMB, Microsoft has continued to change and enhance the protocol, each time assigning a new version number to SMB. The most recent versions are SMB2, SMB2.1, SMB3, and SMB3.02.
    For information about SMB versions, see Overview of SMB Versions 2, 2.1, 3, and 3.02.
    For the purpose of this chapter, the terms SMB and CIFS are used interchangeably.
    RiOS has provided CIFS optimization since version 1.0, with ongoing enhancements in each subsequent version. CIFS optimization focuses on reducing the impact of WAN round-trip latency of common application and system behavior, including the Microsoft Office product suite, general file access, and remote printing. Ongoing work has been necessary to adjust to new incremental changes introduced to the protocol from Microsoft, typically with each new Microsoft operating system version. Additionally, new features have been added that enhance and broaden the applicability of the CIFS optimization.
    RiOS includes optimization for SMB signed traffic. SMB signed refers to an optional feature in which the client and server, using the CIFS protocol, use cryptographic techniques to sign each protocol datagram exchanged in a CIFS session. This technique does not encrypt data passing through the network; it merely authenticates that the client and server receive datagrams that have not been modified by unauthorized middle devices. Through specific configuration and integration into the Windows security domain, RiOS can perform full latency and bandwidth optimization securely for SMB signed traffic, while still maintaining the end-to-end authentication that SMB signing was designed to achieve.
    While SMB signing does not encrypt the data, SMB3 can encrypt traffic. If you use the correct RiOS release with the appropriate configuration settings, RiOS can continue to provide full-latency and bandwidth optimization while maintaining a secure client-server communication.
    For information about configuring CIFS optimization, see the SteelHead Management Console User’s Guide.