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675:, i.e., 5 Gbit of unacknowledged data in flight. Despite having much lower latencies than satellite links, even terrestrial fiber links can have very high BDPs because their link capacity is so large. Operating systems and protocols designed as recently as a few years ago when networks were slower were tuned for BDPs of orders of magnitude smaller, with implications for limited achievable performance.
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1003:(RFC 1323) play a double role: they avoid ambiguities due to the 32-bit sequence number field wrapping around, and they allow more precise RTT estimation in the presence of multiple losses per RTT. With those improvements, it becomes reasonable to increase the TCP window beyond 64 kB, which can be done using the
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Buffering is used throughout high performance network systems to handle delays in the system. In general, buffer size will need to be scaled proportionally to the amount of data "in flight" at any time. For very high performance applications that are not sensitive to network delays, it is possible to
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allocate the same amount of memory as the receive side for good performance. That is because, even after data has been sent on the network, the sending side must hold it in memory until it has been acknowledged as successfully received, just in case it would have to be retransmitted. If the receiver
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Maximum achievable throughput for a single TCP connection is determined by different factors. One trivial limitation is the maximum bandwidth of the slowest link in the path. But there are also other, less obvious limits for TCP throughput. Bit errors can create a limitation for the connection as
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can limit throughput. Because TCP transmits data up to the window size before waiting for the acknowledgements, the full bandwidth of the network may not always get used. The limitation caused by window size can be calculated as follows:
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is far away, acknowledgments will take a long time to arrive. If the send memory is small, it can saturate and block emission. A simple computation gives the same optimal send memory size as for the receive memory size given above.
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At any given time, the window advertised by the receive side of TCP corresponds to the amount of free receive memory it has allocated for this connection. Otherwise it would risk dropping received packets due to lack of space.
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interpose large end to end buffering delays by putting in intermediate data storage points in an end to end system, and then to use automated and scheduled non-real-time data transfers to get the data to their final endpoints.
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option (SACK, RFC 2018) allows a TCP receiver to precisely inform the TCP sender about which segments have been lost. This increases performance on high-RTT links, when multiple losses per window are possible.
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networks. Well-tuned networks can perform up to 10 times faster in some cases. However, blindly following instructions without understanding their real consequences can hurt performance as well.
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occurs in the network, an additional limit is imposed on the connection. In the case of light to moderate packet loss when the TCP rate is limited by the
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1190:- Forward RTO-Recovery (F-RTO): An Algorithm for Detecting Spurious Retransmission Timeouts with TCP and the Stream Control Transmission Protocol (SCTP)
694:- 1) bytes, which was adequate for slow links or links with small RTTs. Larger buffers are required by the high performance options described below.
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necessary to fill a TCP "path", i.e. it is equal to the maximum number of simultaneous bits in transit between the transmitter and the receiver.
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A number of extensions have been made to TCP over the years to increase its performance over fast high-RTT links ("long fat networks" or LFNs).
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is the probability of packet loss. If packet loss is so rare that the TCP window becomes regularly fully extended, this formula doesn't apply.
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client should be able to transmit a packet every 20 ms. The estimated maximum number of packets in transit would then be:
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972:{\displaystyle \mathrm {Throughput} \leq {\frac {\mathrm {MSS} }{\mathrm {RTT} {\sqrt {P_{\mathrm {loss} }}}}}}
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having a speed of 20 Mbit/s and an average packet size of 750 byte. How large should the IP queue be? A
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High performance networks have very large BDPs. To give a practical example, two nodes communicating over a
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can accept without acknowledging the sender. If the sender has not received acknowledgement for the first
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835:{\displaystyle \mathrm {Throughput} \leq {\frac {\mathrm {RWIN} }{\mathrm {RTT} }}\,\!}
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it sent, it will stop and wait and if this wait exceeds a certain limit, it may even
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where RWIN is the TCP Receive Window and RTT is the round-trip time for the path.
652:(BDP) is a term primarily used in conjunction with TCP to refer to the number of
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1183:- A Conservative Selective Acknowledgment-based Loss Recovery Algorithm for TCP
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The default IP queue length is 1000, which is generally too large. Imagine a
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872:, the limit can be calculated according to the formula (Mathis, et al.):
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27:
Techniques to increase throughput over the transmission control protocol
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1176:- An Extension to the Selective Acknowledgment (SACK) Option for TCP
1112:"The Macroscopic Behavior of the TCP Congestion Avoidance Algorithm"
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1169:- Enhancing TCP Over Satellite Channels using Standard Mechanisms
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667:(or round-trip time, RTT) of 0.5 seconds and a bandwidth of 10
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1027:, increasing the performance in the presence of packet loss.
1162:- The NewReno Modification to TCP's Fast Recovery Algorithm
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Estimated buffer size = 20000000 * 0,020 / 8 / 750 = 66
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165:. Unsourced material may be challenged and removed.
1255:Pittsburgh Supercomputing Center TCP tuning guide
971:
834:
733:(TCP Receive Window) is the amount of data that a
831:
1245:, Microsoft Windows Server Performance Team Blog
752:Even if there is no packet loss in the network,
1200:The Cable Guy: TCP Receive Window Auto-Tuning
598:
8:
66:Learn how and when to remove these messages
981:where MSS is the maximum segment size and
683:The original TCP configurations supported
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243:Learn how and when to remove this message
225:Learn how and when to remove this message
123:Learn how and when to remove this message
1228:Information on 'Tweaking' your TCP stack
86:This article includes a list of general
1224:performance parameters in the registry.
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1052:ifconfig wlan0 mtu 1492 txqueuelen 100
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479:
429:
264:
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1155:- TCP Selective Acknowledgment Options
1148:- TCP Extensions for High Performance
7:
1243:NTTTCP Network Performance Test Tool
1087:"High Performance SSH/SCP - HPN-SSH"
745:. This is how TCP achieves reliable
163:adding citations to reliable sources
1249:Best Practices for TCP Optimization
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640:Network and system characteristics
92:it lacks sufficient corresponding
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1205:The Web100 Data Bandwidth Testing
47:This article has multiple issues.
1067:Explicit Congestion Notification
1049:A better queue length would be:
992:TCP options for high performance
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1023:avoids the need for in-network
150:needs additional citations for
55:or discuss these issues on the
870:congestion avoidance algorithm
1:
1271:Transmission Control Protocol
645:Bandwidth-delay product (BDP)
626:Transmission Control Protocol
628:(TCP) connections over high-
622:network congestion avoidance
671:can have up to 0.5×10
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1220:) which can quickly alter
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1014:selective acknowledgment
851:The sending side should
1031:Tuning slow connections
717:TCP window scale option
685:TCP receive window size
661:geostationary satellite
650:Bandwidth-delay product
259:Internet protocol suite
107:more precise citations.
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836:
620:techniques adjust the
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665:round-trip delay time
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690:of up to 65,535 (64
159:improve this article
1276:Network performance
1009:option (RFC 1323).
727:computer networking
1037:Wi-Fi base station
1021:Path MTU Discovery
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1232:Broadband Reports
1214:Microsoft Windows
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747:data transmission
721:Congestion window
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266:Application layer
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16:(Redirected from
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1212:- a utility for
1194:TCP Tuning Guide
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702:TCP speed limits
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1122:on May 11, 2012
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176: –
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170:Find sources:
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148:This article
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1124:. Retrieved
1120:the original
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1094:. Retrieved
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663:link with a
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215:January 2017
212:
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181:
174:"TCP tuning"
169:
157:Please help
152:verification
149:
119:
113:January 2017
110:
91:
63:
56:
50:
49:Please help
46:
29:
1096:January 23,
1062:Bufferbloat
866:packet loss
860:Packet loss
711:Window size
105:introducing
1265:Categories
1251:- ExtraHop
1216:(prior to
1126:January 3,
1073:References
1001:timestamps
743:retransmit
715:See also:
618:TCP tuning
548:Link layer
185:newspapers
88:references
52:improve it
1186:RFC
1179:RFC
1172:RFC
1165:RFC
1158:RFC
1151:RFC
1144:RFC
914:≤
799:≤
754:windowing
630:bandwidth
58:talk page
1056:See also
1012:The TCP
735:computer
1257:, - PSC
1196:, ESnet
1116:Psc.edu
1091:Psc.edu
688:buffers
679:Buffers
634:latency
632:, high-
578:more...
562:Tunnels
538:more...
471:more...
421:more...
410:TLS/SSL
365:ONC/RPC
302: (
199:scholar
101:improve
739:packet
669:Gbit/s
405:Telnet
304:HTTP/3
201:
194:
187:
180:
172:
90:, but
1218:Vista
1210:DrTCP
864:When
673:Gbits
654:bytes
532:IPsec
310:HTTPS
206:JSTOR
192:books
1188:4138
1181:3517
1174:2883
1167:2488
1160:2582
1153:2018
1146:1323
1128:2017
1098:2020
999:TCP
986:loss
853:also
731:RWIN
719:and
527:IGMP
507:ICMP
465:QUIC
460:RSVP
455:SCTP
450:DCCP
415:XMPP
395:SNMP
390:SMTP
375:RTSP
350:OSPF
340:NNTP
335:MQTT
330:MGCP
325:LDAP
315:IMAP
300:HTTP
280:DHCP
178:news
1222:TCP
725:In
692:KiB
572:MAC
567:PPP
557:ARP
522:ECN
517:NDP
445:UDP
440:TCP
400:SSH
385:SIP
380:RIP
370:RTP
360:PTP
355:POP
345:NTP
320:IRC
295:FTP
290:DNS
275:BGP
161:by
1267::
1230:,
1114:.
1089:.
749:.
729:,
511:v6
500:v6
495:v4
490:IP
284:v6
61:.
1130:.
1100:.
983:P
959:s
956:s
953:o
950:l
945:P
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935:T
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904:p
901:h
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895:u
892:o
889:r
886:h
883:T
825:T
822:T
819:R
814:N
811:I
808:W
805:R
795:t
792:u
789:p
786:h
783:g
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774:r
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213:(
203:·
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64:(
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