| 1. |
- Ahlgren, Bengt, et al.
(författare)
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A Host Interface to the DTM Network
- 1992. - 1
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- DTM, dynamic synchronous transfer mode, is a new time division multiplexing technique for fiber networks currently being developed and implemented at the Royal Institute of Technology in Stockholm, Sweden. This paper describes the hardware and software aspects of the design of an SBus host interface to the DTM network for a Sun SPARCstation. The interface is based on a dual port memory residing on the interface card and accesible over the SBus from the host CPU. The host operating system allocates message buffers directly in this memory. The interface has hardware support for segmenting and reassembling packets to and from the data units of the DTM. The software part of the interface manages the shared memory and the virtual circuits provided by the DTM network.
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| 2. |
- Bodin, Ulf, et al.
(författare)
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Load-tolerant differentiation with active queue management
- 2000
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Ingår i: Computer communication review. - : Association for Computing Machinery (ACM). - 0146-4833 .- 1943-5819. ; 30:3, s. 4-16
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Tidskriftsartikel (refereegranskat)abstract
- Current work in the IETF aims at providing service differentiation on the Internet. One proposal is to provide loss differentiation by assigning levels of drop procedence to IP packets. In this paper, we evaluate the active queue management (AQM) mechanisms RED In and Out (RIO) and Weighted RED (WRED) in providing levels of drop precedence under different loads. For low drop precedence traffic, FIO and WRED can be configured to offer sheltering (i.e., low drop precedence traffic is protected from losses caused by higher drop precedence traffic). However, if traffic control fails or is inaccurate, such configurations can cause starvation of traffic at high drop precedence levels. Configuring WRED to instead offer relative differentiation can eliminate the risk of starvation. However, WRED cannot, without reconfiguration, both offer sheltering when low drop precedence traffic is properly controlled and avoid starvation at overload of low drop precedence traffic. To achieve this, we propose a new AQM mechanism, WRED with Thresholds (WRT). The benefit of WRT is that, without reconfiguration, it offers sheltering when low drop precedence traffic is properly controlled and relative differentiation otherwise. We present simulations showing that WRT has these properties.
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| 3. |
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| 4. |
- Degermark, Mikael, et al.
(författare)
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Advance reservations for predictive service
- 1995
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Ingår i: Network and Operating Systems Support for Digital Audio and Video. - Berlin : Encyclopedia of Global Archaeology/Springer Verlag. - 9783540606475 ; , s. 1-15
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Konferensbidrag (refereegranskat)abstract
- We extend a measurement-based admission control algorithm suggested for predictive service to provide advance reservations for guaranteed and predictive service while keeping the attractive features of predictive service. The admission decision for advance reservations is based on information about flows that overlap in time. For flows that have not yet started, the requested values are used, and for those that have already started measurements are used. This allows us to estimate the network load accurately for the near future. To provide advance reservations we ask users to include durations in their requests. We provide simulation results to show that predictive service with advance reservations provides utilization levels significantly higher than those for guaranteed service.
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| 5. |
- Degermark, Mikael, et al.
(författare)
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Advance reservations for predictive service in the Internet
- 1997
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Ingår i: Multimedia Systems. - : Springer Science and Business Media LLC. - 0942-4962 .- 1432-1882. ; 5:3, s. 177-186
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Tidskriftsartikel (refereegranskat)abstract
- We extend a measurement-based admission control algorithm suggested for predictive service to provideadvance reservations for guaranteed and predictive service.while retaining the attractive features of predictive service.The admission decision for advance reservations is based oninformation about flows that overlap in time. For flows thathave not yet started, the requested values are used, and forthose that have already started measurements are used. Thisallows us to estimate the network load accurately for thenear future. To provide advance reservations we ask usersto include durations in their requests. We present simulationresults to show that predictive service with advance reservations provides utilization levels significantly higher thanthose for guaranteed service, and comparable to those forpredicted service without advance reservations. Those utilization levels are reached without any preemption of otheradmitted flows. Finally, we discuss how to setup advancereservations over multiple hops in the Internet using resourcereservation setup protocols.
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| 6. |
- Degermark, Mikael, et al.
(författare)
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Issues in the design of a new network protocol
- 1996
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Ingår i: Multimedia Telecommunications and Applications. - Berlin : Encyclopedia of Global Archaeology/Springer Verlag. ; , s. 169-182
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Konferensbidrag (refereegranskat)abstract
- We describe some of the issues in the design of a new packet switched network protocol. Adaptation to various network technologies along the dimensions of speed, error model, robustness, etc., is a goal for this new protocol. We look at the adaption in size of the packet header to the speed and robustness of the underlying network to allow efficient communication on low-speed wireless networks, for example. We also explore issues in resource reservation and multicast for real-time multimedia, the notion of a network "flow", a hybrid of datagrams and virtual circuits, and suggest common solutions for both mobile and multicast routing. The authors are engaged in the design of a network protocol, NP++, whose goal is flexibility over a wide dynamic range of speeds and varying kinds of hardware switching elements.
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| 7. |
- Degermark, Mikael, et al.
(författare)
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Low-loss TCP/IP header compression for wireless networks
- 1997
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Ingår i: Wireless networks. - 1022-0038 .- 1572-8196. ; 3:5, s. 375-387
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Tidskriftsartikel (refereegranskat)abstract
- Wireless is becoming a popular way to connect mobile computers to the Internet and other networks. The bandwidth of wireless links will probably always be limited due to properties of the physical medium and regulatory limits on the use of frequencies for radio communication. Therefore, it is necessary for network protocols to utilize the available bandwidth efficiently. Headers of IP packets are growing and the bandwidth required for transmitting headers is increasing. With the coming of IPv6 the address size increases from 4 to 16 bytes and the basic IP header increases from 20 to 40 bytes. Moreover, most mobility schemes tunnel packets addressed to mobile hosts by adding an extra IP header or extra routing information, typically increasing the size of TCP/IPv4 headers to 60 bytes and TCP/IPv6 headers to 100 bytes. In this paper, we provide new header compression schemes for UDP/IP and TCP/IP protocols. We show how to reduce the size of UDP/IP headers by an order of magnitude, down to four to five bytes. Our method works over simplex links, lossy links, multi-access links, and supports multicast communication. We also show how to generalize the most commonly used method for header compression for TCP/IPv4, developed by Jacobson, to IPv6 and multiple IP headers. The resulting scheme unfortunately reduces TCP throughput over lossy links due to unfavorable interaction with TCP's congestion control mechanisms. However, by adding two simple mechanisms the potential gain from header compression can be realized over lossy wireless networks as well as point-to-point modem links.
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| 8. |
- Degermark, Mikael, et al.
(författare)
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Low-loss TCP/IP header compression for wireless networks
- 1996
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Ingår i: Proceedings of the annual international conference on mobile computing and networking ; 2nd. - : IEEE Communications Society. - 089791872X ; , s. 1-14
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Konferensbidrag (refereegranskat)abstract
- Wireless is becoming a popular way to connect mobile computers to the Internet and other networks. The bandwidth of wireless links will probably always be limited due to properties of the physical medium and regulatory limits on the use of frequencies for radio communication. Therefore, it is necessary for network protocols to utilize the available bandwidth efficiently. Headers of IP packets are growing and the bandwidth required for transmitting headers is increasing. With the coming of IPv6 the address size increases from 4 to 16 bytes and the basic IP header increases from 20 to 40 bytes. Moreover, most mobility schemes tunnel packets addressed to mobile hosts by adding an extra IP header or extra routing information, typically increasing the size of TCP/IPv4 headers to 60 bytes and TCP/IPv6 headers to 100 bytes. In this paper, we provide new header compression schemes for UDP/IP and TCP/IP protocols. We show how to reduce the size of UDP/IP headers by an order of magnitude, down t...
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| 9. |
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| 10. |
- Degermark, Mikael, et al.
(författare)
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Small forwarding tables for fast routing lookups
- 1997
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Ingår i: Computer communication review. - Luleå : Luleå tekniska universitet. - 0146-4833 .- 1943-5819. ; 27:4, s. 3-14
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For some time, the Internet community has believed that it is impossible to do IP routing lookups in software fast enough to support gigabit speeds. IP routing lookups must find the routing entry with the longest matching prefix, a task that has been thought to require hardware support at lookup frequencies of millions per second. We present a forwarding table data structure designed for quick routing lookups. Forwarding tables are small enough to fit in the cache of a conventional general purpose processor. With the table in cache, a 200 MHz Pentium Pro or a 333 MHz Alpha 21164 can perform a few million lookups per second. This means that it is feasible to do a full routing lookup for each IP packet at gigabit speeds without special hardware. The forwarding tables are very small, a large routing table with 40,000 routing entries can be compacted to a forwarding table of 150--160 Kbytes. A lookup typically requires less than 100 instructions on an Alpha, using eight memory references accessing a total of 14 bytes.
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