What is a SMB protocol?

7330 pts.
CPU usage
Domain Controller
Microsoft Windows Server 2003
Windows Server
Windows Server Performance
We have Windows 2003 Servers as our domain controller. We are facing some problem with CPU utilization. When I captured to traffic using sniffers, I figured out a protocol called SMB which is frequently used by clients to communicate with Domain Controllers. I am wondering what is this SMB protocol?

Software/Hardware used:
Windows 2003, Domain Controllers, CPU utlization, protocols, sniffer

Answer Wiki

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SMB, which stands for Server Message Block, is a protocol for sharing files, printers, serial ports, and communications abstractions such as named pipes and mail slots between computers.

SMB is a client server, request-response protocol. . The only exception to the request-response nature of SMB (that is, where the client makes requests and the server sends back responses) is when the client has requested opportunistic locks (oplocks) and the server subsequently has to break an already granted oplock because another client has requested a file open with a mode that is incompatible with the granted oplock. In this case, the server sends an unsolicited message to the client signalling the oplock break.

Servers make file systems and other resources (printers, mailslots, named pipes, APIs) available to clients on the network. Client computers may have their own hard disks, but they also want access to the shared file systems and printers on the servers


Discuss This Question: 3  Replies

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  • Pjb0222
    Many things in Windows use SMB. Items such as file shares and inter system communications. So the login share and group policy share will both have SMB traffic and some login traffic may use SMB. CIFS is an effort to rebrand SMB by Microsoft. Here's everything you need to know about SMB protocol.
    3,310 pointsBadges:
  • Kevin Beaver
    If you run a network analyzer to monitor the network backbone or the server itself you'll likely see that CIFS/SMB are the protocols used the most. In fact a network analysis may be a good idea to see what's running efficiently and what's not. You'll be surprised at all the junk on any given network that can create network and server utilization issues.
    27,515 pointsBadges:
  • Genderhayes
    Network file sharing protocol runs at a higher level on top of other network protocols such as TCP/IP, NetBEUI, or IPX
    10,720 pointsBadges:

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