C. A. Thekkath, T. D. Nguyen, E. Moy, and E. D. Lazowska. Implementing Network Protocols at User Level. IEEE/ACM Transactions on Networking, 1(5):554--565, Nov 1993.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....architecture for constructing and composing network protocols. Reference [13] also provides a taxonomy of key transport system services and illustrates the concepts with a survey of four operating system transport architectures, namely, System V and BSD UNIX, the x kernel, and Choices. Finally, [14] addresses many of the issues related to the implementation of protocol stacks at the user level. In [6] a protocol environment populated by standard communication functions is proposed. Applications have the ability to compose protocol stacks out of the standard protocol entities by ....

....possible protocol stacks are predefined. Traditionally, communication transport systems have resided entirely in the operating system. In our architecture as well as in [6, 8, 9] it is proposed to implement lightweight protocol elements and build the protocol stacks in user space. Refer ence [14] discusses some of the implications for an overall communication system structure to support efficient user level implementation of protocols. Finally, from the standpoint of APIs our architecture is similar in philosophy to the Microsoft Windows open software architecture for which both the APIs ....

C. A. Thekkath et al., "Implementing Network Protocols at User Level," IEEE/ACM Trans. Networking, Oct. 1993; also in Proc. ACM SIGCOMM '93.

....the multicast aspect of the IP protocol, while also considering a similar context to ours, is [5] At present there is a considerable amount of research focusing upon issues of implementing communication protocols at user level. A study based on the Mach operating system is presented in [6], while [7] focuses on Amoeba. Both papers discuss the trade offs of this approach when compared with kernel level implementations, present case studies, and comment on the measurement results obtained. 2 PRELIMINARIES Round Trip Transmission Delay Our approach for measuring the user level ....

C. A. Thekkath, T. D. Nguyen, E. Moy, and E. D. Lazowska. Implementing Network Protocols at User Level. IEEE/ACM Transactions on Networking, 1(5), 554--565, 1993.

....All of the systems mentioned here fail to couple protocol implementation and application tightly. Although application control over network protocol implementation is improved, the implementation is still physically located in system software. d) Application level networking: Thekkath et al. [18] designed a system, where protocols were implemented in userlevel libraries. The system is based on a microkernel architecture, but protocols are linked with applications. However, the system requires a registry server for some operations, such as establishing connections. Therefore, the need for ....

C. A. Thekkath, T. D. Nguyen, E. Moy, and E. D. Lazowska, "Implementing network protocols at user level," IEEE/ACM Transactions on Networking, vol. 1, no. 5, pp. 554--565, 1993.

....customize protocols depending on their specific requirements; The process scheduling policies of the OS kernel trivially cover both application and protocol processing, which makes the task of QoS enforcement within the end system easier. 19 Recently, there have been several research efforts [17,18,24,33,40] that have attempted to make user level library implementations of protocol stacks, in such a way that they can be linked with application programs. Most of these efforts have relied on traditional network interfaces, which necessitate that the device driver be kernel resident. Thus, even though ....

Thekkath, C., Nguyen, T., Moy, E., and Lazowska, E. "Implementing Network Protocols at User Level," Proc. ACM SIGCOMM `93, Sep. 1993.

....of Arizona supports the implementation of TCP IP at user space. With this implementation, the code can be modified so that the network traffic can be controlled and monitored and serve the purpose of debugging. A similar concept but different implementation was done at the University of Washington [16], which supports user level protocol. Multiple protocols can co exist. Similar to the work of x kernel, the code can be modified to support the debug of distributed programming. NEST [6] is a network simulation tool. It can alter the characteristics of network traffic to help identify bugs in any ....

C.A. Thekkath, T.D. Nguyen, E. Moy, E.D. Lazowska, Implementing Network Protocol at User Level, Technical Report 93-03-01, Department of Computer Science and Engineering, University of Washington, Mar 1993

....networks such as Ether net are unable to do this. D. User level protocol processing Common arguments for implementing network protocols in user space include increased flexibility, easier maintenance, and the possibility of application specific optimizations offering better performance [12], 13] 14] A further advantage is that it provides a natural solution to the problems of resource accountability and minimization of QoS crosstalk. Compared to LRP, scheduling jitter caused by non preemptable network processing is further reduced, and applications remain in control of when they ....

C. Thekkath, T. Nguyen, E. Moy, and E. Lazowska, "Implementing network protocols at user level," in Proceedings ofACM SIGCOMM '93, September 1993, pp. 64-73.

....functions being implemented on todays high speed ATM adapters. A second argument for a user level implementation is to provide the application with a dedicated implementation of the protocol stack that allows better control over protocol processing to guarantee the QoS of the networked data [THEK 93, EDWA 94] 2 Concept ATM (Asynchronous Transmission Mode) and its Adaptation Layer (AAL) offer a technology for the physical layer and the link layer of high speed LANs and WANs. The AAL offers a connection oriented frame transfer service on top of ATM. The AAL functions to reassemble a frame ....

C. Thekkath, T. Nguyen, E. Moy and E. Lazowska, "Implementing Network Protocol at User Level", IEEE/ACM Transaction on Networking, 1(5):554--565, October 1993. 11

....the NIC should have at least some level of support for OS bypass, such as multiple transmit and receive queues that can be split between applications. The NIC on the receiver must also be able to distinguish between different applications and place the incoming packets on the correct receive queue [37, 38]. To enable applications use of these facilities several different interfaces, such as UNet [38] libst [39, 40] and VIA [41] have been developed. These libraries provide a hardware independent method of using OS bypass, yet remaining relatively low level to provide the best possible ....

Tekkath C., Nguyen T., Moy E. & Lazowska E. (1993) Implementing Network Protocols at User Level. In: SIGCOMM '93, September 13-17, San Francisco, USA, pp. 64-73.

....data to any types, it is not enough safe. Additionally, because all memory accesses cannot be checked statically, SPIN also needs runtime checks like an array range check. 2.2. 4 User Level Library per Application The Exokernel operating system [11, 16] or some systems using protocol library [23, 48] link the functions of operating systems as a library with application programs. The fail safety is su#cient since an only application with which the library is linked is a#ected if the extension module created as a library crashes. In Exokernel, almost all functions of operating systems are ....

Thekkath, C. A., T. D. Nguyen, E. Moy, and E. D. Lazowska, "Implementing Network Protocols at User Level," in Proceedings of the ACM SIGCOMM'93 Symposium on Communications Architectures and Protocols, pp. 64--73, Sep. 1993.

....cluster processing[8, 32] In contrast, Alpine is focused on normal applications that use normal networking APIs. 2. Per application specialization. Many have shown that special kernel modifications or downloadable kernel code make application specialization of the networking stack possible [7, 9, 14, 15, 21, 24, 27, 29, 33]. Alpine supports specialization, but this is not its focus. Since our design constraints include requiring no kernel or application modifications, Alpine cannot achieve the high performance of many of these systems. 3. Simplified development. Work has also been done to make kernel development ....

....process does not exit cleanly, the firewall may not be uninstalled properly, preventing other applications from using the blocked ports. Centralizing port allocation for Alpine processes is a reasonable way to ensure that the firewall remains consistent. Our approach is similar to that proposed in [29], which uses a dedicated registry server to handle connection setup and teardown. Allocating Alpine file descriptors For security reasons, applications in Unix cannot directly access a file on disk. Rather, they refer to open files using a file descriptor, which is merely an index into a ....

C. Thekkath, T. Nguyen, E. Moy, and E. Lazowska. Implementing network protocols at user level. IEEE/ ACM Transactions on Networking, 1(5):554--565, October 1993.

....real time OS, such as Solaris, only provides a fixed number of priority levels and is not geared towards the periodic scheduling of various multimedia applications. Another approach of supporting different priorities in protocol processing is to implement the protocol stack as a user library [3, 10, 11, 12, 13]. As a result, communication protocol processing becomes an extension of process threads and can be treated as fully preemptive blocks by the OS scheduler. The advantages of implementing protocol in the user space are implementation flexibility, easiness of debugging and modification, and allowing ....

C.A. Thekkath, T.D. Nguyen, E. Moy, and E.D. Lazowska. Implementing network protocols at user level. In ACM SIGCOMM, Sept 93.

....set by our communication subsystem scheduler in accordance with the current QoS level selection. While a server based implementation is natural for a microkernel operating system, it may perform poorly compared to user level protocol libraries due to excessive data copying and context switching [85, 134]. Implementing the service as a protocol library, however, distributes the functions of admission control and run time resource management among several address spaces. Since applications may each compete for communication resources, controlling system wide resources is more effectively done when ....

C. A. Thekkath, T. D. Nguyen, E. Moy, and E. Lazowska, "Implementing network protocols at user level," IEEE Transactions on Networking, vol. 1, no. 5, pp. 554--565, October 1993.

....clients cannot write on input buffers; after cached fbuf output requests, clients cannot write on output buffers. In contrast, I O oriented IPC imposes only soft, advisory conditions, which preserve compatibility. 3. Preservation of server organization and interfaces Some previous works [13] [21] have avoided IPC by installing drivers in the kernel and decomposing each remaining user level server into a fastpath component, which is linked as a library with user applications and processes common input and output requests, and a slowpath component, which remains a separate user level server ....

....preserve copy semantics and therefore causes incompatibilities with many existing applications. 2. The input and output functionality of any required servers and driver must be linked as a library with the user application. As discussed in the Introduction, librarybased, decomposed servers [13] [21] can be considerably more complex than equivalent monolithic or microkernel servers and may not always be feasible. For example, for quality of service guarantees, network drivers must schedule packets globally, which may be unsafe in code linked with user applications. 3. Few adapters have ....

C. Thekkath, T. Nguyen, E. Moy and E. Lazowska. "Implementing Network Protocols at User Level", in Proc. SIGCOMM'93, ACM, Sept. 1993, pp. 64-73.

....protocols as a library in user space. The trade offs are similar to those of other design choices for microkernels: implementing functionality in user space is more flexible but potentially less efficient. Several researchers have implemented protocols like TCP IP and UDP IP in user space [12, 16]. They describe many advantages of this approach. For example, it eases maintenance and debugging, allows the co existence of This research was supported in part by a PIONIER grant from the Netherlands Organization for Scientific Research (N.W.O. multiple protocols, and makes it possible to use ....

....nonblocking broadcasts can be used without violating Orca s sequential consistency semantics. With the Amoeba broadcast protocol this optimization would require modifications to the kernel. Our work is related to several other systems. Implementations of user space protocols are also studied in [12, 16]. These studies use a reliable byte stream protocol (TCP IP) and an unreliable datagram protocol (UDP IP) Our work is based on the same motivations. A significant contribution of our work is that we have written several parallel applications on top of the kernel space and user space protocols. We ....

C.A. Thekkath, T.D. Nguyen, E. Moy, and E.D. Lazowska. Implementing network protocols at user level. In Proc. of the SIGCOMM '93 Symposium, September 1993.

....up the matching process by merging the common prefixes of the filter predicates. Aegis uses a declarative language that allows greater merging,and exploits dynamic code generation to remove a layer of interpretation in the matching process [EP94] code generation for filters was first proposed in [TNML93] Network protocol execution can be split between a server and library code to provide both efficiency and some degree of security [TNML93, MB93] Heavyweight and infrequent operations like connection startup happen through a trusted server. The server installs a packet filter in the kernel to ....

.... exploits dynamic code generation to remove a layer of interpretation in the matching process [EP94] code generation for filters was first proposed in [TNML93] Network protocol execution can be split between a server and library code to provide both efficiency and some degree of security [TNML93, MB93] Heavyweight and infrequent operations like connection startup happen through a trusted server. The server installs a packet filter in the kernel to forward packets directly to the application. Applications cannot install their own filters; this ensure some security from one application ....

C.A. Thekkath, T.D. Nguyen, E. Moy, and E. Lazowska. Implementing network protocols at user level. Proceedings of the 1993 SIGCOMM Symposium on Communications Architecture, 1993.

....processor for a TCP (or UDP) connection. Packet filters are becoming more popular (and efficient [3, 75] in contemporary operating systems since early demultiplexing yields other performance gains. For example, depositing received packets directly into application buffers avoids copying data [15, 41, 70]. Our use of a packet filter, to demultiplex to the appropriate virtual processor, simply leverages this existing mechanism for an additional purpose. 2.3.2 Connection Level Parallel Protocols Our Internet protocols are all based on the uniprocessor implementations distributed with the December ....

Thekkath, C. A., Nguyen, T. D., Moy, E., and Lazowska, E. D. Implementing network protocols at user level. In SIGCOMM Symposium on Communications Architectures and Protocols, pages 64--73, San Francisco, CA, Sept. 1993. ACM.

....requirements, and configurability through the composition of basic protocol functions. There are two points of departure from a classical kernel based architecture: designing a new operating system abstractions, as with [1] 2] 3] and moving the communication services out of the kernel, as with [4][5] 6] 7] The x kernel [1] and ADAPTIVE [2] approaches overcome inflexibility in protocol implementation and deployment through composing protocol functions via miniprotocols or protocol machines. The Conduit [3] model uses object oriented language constructs and design methods such as ....

....uses object oriented language constructs and design methods such as inheritance, dynamic binding, and delegation to implement the protocol state machine in a highly modular fashion. The Jetstream and Afterburner [5] 6] experience prove the viability of circumventing the kernel. Library approaches [4][7] move much of the protocol processing into the user process, enhancing code maintenance, debugging, and experimentation. Our approach combines the software engineering attributes of object oriented development environments without the ambition of an entirely new operating system or ....

Thekkath, C. A., Nguyen, T. D., Moy, E., and Lazowska, E. D., "Implementing Network Protocols at User Level," Proceedings of SIGCOMM '93, San Francisco, Ca., September

....linked lists for reassembly, incoming cells are reassembled such that consecutive cells are stored in consecutive memory areas. The demultiplexer is the interface between the network access unit and the processor modules. A similar component to support efficient demultiplexing has been proposed in [24]. The demultiplexer [22] has to distribute incoming P frames to the appropriate processor module, but distribution is performed on the level of ATM cells. The corresponding processor module of a P frame is identified by the FSM address, which addresses a single FSM and is an extension of the ....

Thekkath, C. A.; Nguyen, T.D.; Moy, E.; Lazowska, E.D.: Implementing Network Protocols at User Level, ACM Sigcomm'93 Conference Proceedings, San Francisco, CA, September13-17, 1993, pp. 64-73

....one and an out of kernel one. This approach focuses on investigating the role of each scheduler and the interface between them. x kernel [6] supplies an integrated interface to implement a protocol at the user level. Thekkath s group implements a TCP IP protocol handler as a user level library [7]. The protocol handlers of these systems are implemented at the user level; however it is necessary to modify and or extend their kernels. The objective of all of these projects is to implement a portable communication system. Our objective is the same, but we use an existing communication ....

Thekkath, C., Eguyen, T., and Lazowska, E., "Implementing Network Protocols at User Level," Proceedings of SIGCOMM '93, ACM, Sep. 1993.

....handling of network traffic at sending and receiving hosts. We realize this service architecture as a user level CORDS server running on the OSF MK 7.2 microkernel. Even though server based protocol stacks perform poorly compared to user level protocol libraries or in kernel implementations [112, 168], we choose a server configuration for several reasons. A server configuration considerably eases software development and debugging, particularly the location and correction of timing related bugs. More importantly, since several applications can establish multiple QoS connections, admission ....

....needless code bloat and potentially degraded performance. The final reason is related to performance. A server based implementation is natural for a microkernel operating system, but may perform poorly compared to user level protocol libraries due to excessive data copying and context switching [112, 168]. As mentioned in Section 5.1, it seems appropriate to be conservative when building a guaranteed QoS communication service. It follows that in the worst case, compared to user level libraries a server configuration only suffers from additional context switches. While this has significant ....

[Article contains additional citation context not shown here]

C. A. Thekkath, T. D. Nguyen, E. Moy, and E. Lazowska, "Implementing network protocols at user level," IEEE/ACM Trans. Networking, vol. 1, no. 5, pp. 554--565, October 1993.

No context found.

C. A. Thekkath, T. D. Nguyen, E. Moy, and E. D. Lazowska. Implementing Network Protocols at User Level. IEEE/ACM Transactions on Networking, 1(5):554--565, Nov 1993.

No context found.

Thekkath, C., Nguyen, T., Moy, E., et al. Implementing network protocols at user level. In Proceedings of the SIGCOMM `93 Symposium (Sept. 1993).

No context found.

C. A. Thekkath, T. D. Nguyen, E. Moy and E. D. Lazowska. Implementing network protocols at user level. In Proceedings of ACM SIGCOMM, pages 64-73, September 1993.

No context found.

C.A. Thekkath, T.D. Nguyen, Evelyn Moy and E.D. Lazowska. Implementing Network Protocols at User Level. ACM Sigcomm, 1993.

No context found.

C. A. Thekkath, T. D. Nguyen, E. Moy, and E. Lazowska, "Implementing network protocols at user level," in Proc. of ACM SIGCOMM, pp. 64--73, San Francisco, California, October 1993.

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