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39-496: Sun used version 1 only for in-house experimental purposes. When the development team added substantial changes to NFS version 1 and released it outside of Sun, they decided to release the new version as v2, so that version interoperation and RPC version fallback could be tested. Version 2 of the protocol (defined in RFC 1094, March 1989) originally operated only over User Datagram Protocol (UDP). Its designers meant to keep

78-667: A data section (the payload data for the application). The UDP datagram header consists of 4 fields, each of which is 2 bytes (16 bits): The use of the Checksum and Source Port fields is optional in IPv4 (light purple background in table). In IPv6 only the Source Port field is optional. If not used, these fields should be set to zero. The method used to compute the checksum is defined in RFC ; 768 , and efficient calculation

117-702: A stateful protocol. Version 4 became the first version developed with the Internet Engineering Task Force (IETF) after Sun Microsystems handed over the development of the NFS protocols. NFS version 4.1 (RFC 5661, January 2010; revised in RFC 8881, August 2020) aims to provide protocol support to take advantage of clustered server deployments including the ability to provide scalable parallel access to files distributed among multiple servers (pNFS extension). Version 4.1 includes Session trunking mechanism (Also known as NFS Multipathing) and

156-500: A carry-out (17th bit) is produced, swing that 17th carry bit around and add it to the least significant bit of the running total. Finally, the sum is then ones' complemented to yield the value of the UDP checksum field. If the checksum calculation results in the value zero (all 16 bits 0) it should be sent as the ones' complement (all 1s) as a zero-value checksum indicates no checksum has been calculated. In this case, any specific processing

195-411: A combination of TCP and TLS to ensure reliability and security respectively. This means that HTTP/3 uses a single handshake to set up a connection, rather than having two separate handshakes for TCP and TLS, meaning the overall time to establish a connection is reduced. Transmission Control Protocol is a connection-oriented protocol and requires handshaking to set up end-to-end communications. Once

234-457: A connection is set up, user data may be sent bi-directionally over the connection. User Datagram Protocol is a simpler message-based connectionless protocol . Connectionless protocols do not set up a dedicated end-to-end connection. Communication is achieved by transmitting information in one direction from source to destination without verifying the readiness or state of the receiver. WebNFS Too Many Requests If you report this error to

273-480: A different header layout, the method used to compute the checksum is changed accordingly: Any transport or other upper-layer protocol that includes the addresses from the IP header in its checksum computation must be modified for use over IPv6, to include the 128-bit IPv6 addresses instead of 32-bit IPv4 addresses. When computing the checksum, again a pseudo header is used that mimics the real IPv6 header : The checksum

312-714: A direct participant in the exact location of file data and to avoid solitary interaction with one NFS server when moving data. In addition to pNFS, NFSv4.1 provides: User Datagram Protocol In computer networking , the User Datagram Protocol ( UDP ) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets ) to other hosts on an Internet Protocol (IP) network. Within an IP network, UDP does not require prior communication to set up communication channels or data paths. UDP

351-540: A high degree of reliability, a protocol such as the Transmission Control Protocol may be used instead. Most often, UDP applications do not employ reliability mechanisms and may even be hindered by them. Streaming media , real-time multiplayer games and voice over IP (VoIP) are examples of applications that often use UDP. In these particular applications, loss of packets is not usually a fatal problem. In VoIP, for example, latency and jitter are

390-419: A method of separating the filesystem meta-data from file data location; it goes beyond the simple name/data separation by striping the data amongst a set of data servers. This differs from the traditional NFS server which holds the names of files and their data under the single umbrella of the server. Some products are multi-node NFS servers, but the participation of the client in separation of meta-data and data

429-432: A pressing issue. At the time of introduction of Version 3, vendor support for TCP as a transport-layer protocol began increasing. While several vendors had already added support for NFS Version 2 with TCP as a transport, Sun Microsystems added support for TCP as a transport for NFS at the same time it added support for Version 3. Using TCP as a transport made using NFS over a WAN more feasible, and allowed

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468-463: A similar agreement to give ISOC change control over NFS, although writing the contract carefully to exclude NFS version 2 and version 3. Instead, ISOC gained the right to add new versions to the NFS protocol, which resulted in IETF specifying NFS version 4 in 2003. By the 21st century, neither DFS nor AFS had achieved any major commercial success as compared to SMB or NFS. IBM, which had formerly acquired

507-423: Is a connectionless protocol meaning that messages are sent without negotiating a connection and that UDP doesn't keep track of what it has sent. UDP provides checksums for data integrity , and port numbers for addressing different functions at the source and destination of the datagram. It has no handshaking dialogues and thus exposes the user's program to any unreliability of the underlying network; there

546-508: Is available in some enterprise solutions as VMware ESXi . NFS version 4.2 (RFC 7862) was published in November 2016 with new features including: server-side clone and copy, application I/O advise, sparse files, space reservation, application data block (ADB), labeled NFS with sec_label that accommodates any MAC security system, and two new operations for pNFS (LAYOUTERROR and LAYOUTSTATS). One big advantage of NFSv4 over its predecessors

585-490: Is available on: During the development of the ONC protocol (called SunRPC at the time), only Apollo's Network Computing System (NCS) offered comparable functionality. Two competing groups developed over fundamental differences in the two remote procedure call systems. Arguments focused on the method for data-encoding — ONC's External Data Representation (XDR) always rendered integers in big-endian order, even if both peers of

624-431: Is computed over the following fields: Lacking reliability, UDP applications may encounter some packet loss, reordering, errors or duplication. If using UDP, the end-user applications must provide any necessary handshaking such as real-time confirmation that the message has been received. Applications, such as TFTP , may add rudimentary reliability mechanisms into the application layer as needed. If an application requires

663-403: Is discussed in RFC  1071 : Checksum is the 16-bit ones' complement of the ones' complement sum of a pseudo header of information from the IP header, the UDP header, and the data, padded with zero octets at the end (if necessary) to make a multiple of two octets. In other words, all 16-bit words are summed using ones' complement arithmetic. Add the 16-bit values up. On each addition, if

702-414: Is documented in RFC  768 . Although UDP provides integrity verification (via checksum ) of the header and payload, it provides no guarantees to the upper layer protocol for message delivery and the UDP layer retains no state of UDP messages once sent. For this reason, UDP sometimes is referred to as Unreliable Datagram Protocol . If transmission reliability is desired, it must be implemented in

741-414: Is generally transmitted using UDP. Real-time video and audio streaming protocols are designed to handle occasional lost packets, so only slight degradation in quality occurs, rather than large delays if lost packets were retransmitted. Because both TCP and UDP run over the same network, in the mid-2000s a few businesses found that an increase in UDP traffic from these real-time applications slightly hindered

780-531: Is identified by the port number , a 16-bit integer value, allowing for port numbers between 0 and 65535. Port 0 is reserved but is a permissible source port value if the sending process does not expect messages in response. The Internet Assigned Numbers Authority (IANA) has divided port numbers into three ranges. Port numbers 0 through 1023 are used for common, well-known services. On Unix -like operating systems , using one of these ports requires superuser operating permission. Port numbers 1024 through 49151 are

819-429: Is limited. The NFSv4.1 pNFS server is a set of server resources or components; these are assumed to be controlled by the meta-data server. The pNFS client still accesses one meta-data server for traversal or interaction with the namespace; when the client moves data to and from the server it may directly interact with the set of data servers belonging to the pNFS server collection. The NFSv4.1 client can be enabled to be

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858-404: Is no guarantee of delivery, ordering, or duplicate protection. If error-correction facilities are needed at the network interface level, an application may instead use Transmission Control Protocol (TCP) or Stream Control Transmission Protocol (SCTP) which are designed for this purpose. UDP is suitable for purposes where error checking and correction are either not necessary or are performed in

897-463: Is not required at the receiver, because all 0s and all 1s are equal to zero in 1's complement arithmetic. The differences between IPv4 and IPv6 are in the pseudo header used to compute the checksum, and that the checksum is not optional in IPv6. Under specific conditions, a UDP application using IPv6 is allowed to use a zero UDP zero-checksum mode with a tunnel protocol. When UDP runs over IPv4,

936-435: Is that only one UDP or TCP port, 2049, is used to run the service, which simplifies using the protocol across firewalls. WebNFS , an extension to Version 2 and Version 3, allows NFS to integrate more easily into Web-browsers and to enable operation through firewalls. In 2007 Sun Microsystems open-sourced their client-side WebNFS implementation. Various side-band protocols have become associated with NFS. Note: NFS

975-750: The Distributed Computing Environment (DCE) and the DCE Distributed File System (DFS) over Sun/ONC RPC and NFS. DFS used DCE as the RPC, and DFS derived from the Andrew File System (AFS); DCE itself derived from a suite of technologies, including Apollo's NCS and Kerberos . Sun Microsystems and the Internet Society (ISOC) reached an agreement to cede "change control" of ONC RPC so that

1014-548: The Open Software Foundation (OSF) in 1988. Ironically, Sun and AT&T had formerly competed over Sun's NFS versus AT&T's Remote File System (RFS), and the quick adoption of NFS over RFS by Digital Equipment, HP, IBM, and many other computer vendors tipped the majority of users in favor of NFS. NFS interoperability was aided by events called "Connectathons" starting in 1986 that allowed vendor-neutral testing of implementations with each other. OSF adopted

1053-402: The registered ports used for IANA-registered services. Ports 49152 through 65535 are dynamic ports that are not officially designated for any specific service and may be used for any purpose. These may also be used as ephemeral ports , which software running on the host may use to dynamically create communications endpoints as needed. A UDP datagram consists of a datagram header followed by

1092-611: The ISOC's engineering-standards body, the Internet Engineering Task Force (IETF), could publish standards documents (RFCs) related to ONC RPC protocols and could extend ONC RPC. OSF attempted to make DCE RPC an IETF standard, but ultimately proved unwilling to give up change control. Later, the IETF chose to extend ONC RPC by adding a new authentication flavor based on Generic Security Services Application Program Interface (GSSAPI), RPCSEC GSS , to meet IETF requirements that protocol standards have adequate security. Later, Sun and ISOC reached

1131-486: The application; UDP avoids the overhead of such processing in the protocol stack . Time-sensitive applications often use UDP because dropping packets is preferable to waiting for packets delayed due to retransmission , which may not be an option in a real-time system . The protocol was designed by David P. Reed in 1980 and formally defined in RFC   768 . UDP is a simple message-oriented transport layer protocol that

1170-445: The checksum is computed using a pseudo header that contains some of the same information from the real IPv4 header . The pseudo header is not the real IPv4 header used to send an IP packet, it is used only for the checksum calculation. UDP checksum computation is optional for IPv4. If a checksum is not used it should be set to the value zero. The checksum is calculated over the following fields: As IPv6 has larger addresses and

1209-444: The concept of a public filehandle (null for NFSv2, zero-length for NFSv3) which could be used as the starting point. Both of those changes have later been incorporated into NFSv4. Version 4 (RFC 3010, December 2000; revised in RFC 3530, April 2003 and again in RFC 7530, March 2015), influenced by Andrew File System (AFS) and Server Message Block (SMB), includes performance improvements, mandates strong security, and introduces

Network File System - Misplaced Pages Continue

1248-733: The connection had little-endian machine-architectures, whereas NCS's method attempted to avoid byte-swap whenever two peers shared a common endianness in their machine-architectures. An industry-group called the Network Computing Forum formed (March 1987) in an (ultimately unsuccessful) attempt to reconcile the two network-computing environments. In 1987, Sun and AT&T announced they would jointly develop AT&T's UNIX System V Release 4. This caused many of AT&T's other licensees of UNIX System to become concerned that this would put Sun in an advantaged position, and ultimately led to Digital Equipment, HP, IBM, and others forming

1287-669: The first 2 GB of a file to be read due to 32-bit limitations. Version 3 (RFC 1813, June 1995) added: The first NFS Version 3 proposal within Sun Microsystems was created not long after the release of NFS Version 2. The principal motivation was an attempt to mitigate the performance issue of the synchronous write operation in NFS Version ;2. By July 1992, implementation practice had solved many shortcomings of NFS Version 2, leaving only lack of large file support (64-bit file sizes and offsets)

1326-496: The performance of applications using TCP such as point of sale , accounting , and database systems (when TCP detects packet loss, it will throttle back its data rate usage). Some VPN systems such as OpenVPN may use UDP and perform error checking at the application level while implementing reliable connections. QUIC is a transport protocol built on top of UDP. QUIC provides a reliable and secure connection. HTTP/3 uses QUIC as opposed to earlier versions of HTTPS which use

1365-458: The primary commercial vendor of DFS and AFS, Transarc , donated most of the AFS source code to the free software community in 2000. The OpenAFS project lives on. In early 2005, IBM announced end of sales for AFS and DFS. In January, 2010, Panasas proposed an NFSv4.1 based on their Parallel NFS (pNFS) technology claiming to improve data-access parallelism capability. The NFSv4.1 protocol defines

1404-785: The primary concerns. The use of TCP would cause jitter if any packets were lost as TCP does not provide subsequent data to the application while it is requesting a re-send of the missing data. Numerous key Internet applications use UDP, including: the Domain Name System (DNS), the Simple Network Management Protocol (SNMP), the Routing Information Protocol (RIP) and the Dynamic Host Configuration Protocol (DHCP). Voice and video traffic

1443-498: The server side stateless , with locking (for example) implemented outside of the core protocol. People involved in the creation of NFS version 2 include Russel Sandberg , Bob Lyon , Bill Joy , Steve Kleiman , and others. The Virtual File System interface allows a modular implementation, reflected in a simple protocol. By February 1986, implementations were demonstrated for operating systems such as System V release 2, DOS , and VAX/VMS using Eunice . NFSv2 only allows

1482-512: The use of larger read and write transfer sizes beyond the 8 KB limit imposed by User Datagram Protocol . WebNFS was an extension to NFSv2 and NFSv3 allowing it to function behind restrictive firewalls without the complexity of Portmap and MOUNT protocols. WebNFS had a fixed TCP/UDP port number (2049), and instead of requiring the client to contact the MOUNT RPC service to determine the initial filehandle of every filesystem, it introduced

1521-404: The user's application. A number of UDP's attributes make it especially suited for certain applications. Applications can use datagram sockets to establish host-to-host communications. An application binds a socket to its endpoint of data transmission, which is a combination of an IP address and a port . In this way, UDP provides application multiplexing . A port is a software structure that

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