Lectures notes for 2010 - KTH
Lectures notes for 2010 - KTH Lectures notes for 2010 - KTH
Multiple simultaneous connections to server GET of a page with multiple objects on it (such as GIF images) - one new connection for each object, all but the first can occur in parallel! 00 port 1114 port 1118 port 1115 port 1116 port 1117 port 1121 port 1119 port 1120 in seconds Figure 4: Timeline of eight TCP connection for a home page and seven GIF images (see Stevens, Vol. 3, figure 113.5, pg. 171) Note that the port 1115, 1116, and 1117 requests start before 1114 terminates, Netscape can initiate 3 non-blocking connects after reading the end-of-file but before closing the first connection. Maguire Hypertext Transfer Protocol (HTTP) 5: 46 of 77 maguire@kth.se 2010.03.21 Internetworking/Internetteknik
Decrease in total time to produce a response: (from Stevens, figure 13.6, Vol. 3, pg. 171) Simultaneous connections Total time (seconds) 1 14.5 2 11.4 3 10.5 4 10.2 5 10.2 6 10.2 7 10.2 Why no improvement beyond 4? • program has an implementation limit of 4, even if you specify more! • gains beyond 4 are probably small (given the small difference between 3 and 4) - but Steven’s has not checked! Maguire Hypertext Transfer Protocol (HTTP) 5: 47 of 77 maguire@kth.se 2010.03.21 Internetworking/Internetteknik
- Page 301 and 302: DNS performance - top 100 From www.
- Page 303 and 304: Web performance - continued Using P
- Page 305 and 306: This lecture we have discussed: •
- Page 307 and 308: IK1550 Internetworking/Internettekn
- Page 309 and 310: Transport layer protocols • User
- Page 311 and 312: Applications which use TCP Lots of
- Page 313 and 314: TCP header continued Reliability is
- Page 315 and 316: time client SYN, seq=x SYN, seq=y,
- Page 317 and 318: client active close ACKs from clien
- Page 319 and 320: Maximum Segment Size • The Maximu
- Page 321 and 322: Window size Increasing window size
- Page 323 and 324: Silly Window Syndrome If receiver a
- Page 325 and 326: Disabling the Nagle Algorithm But s
- Page 327 and 328: Resulting bulk data flow Every segm
- Page 329 and 330: Congestion Avoidance So far we have
- Page 331 and 332: Slow start In 1989, Van Jacobson in
- Page 333 and 334: Round-Trip Time Measurement Fundame
- Page 335 and 336: Congestion Avoidance Algorithm Slow
- Page 337 and 338: Per-Route Metrics Newer TCPs keeps
- Page 339 and 340: TCP Keepalive Timer No data flows a
- Page 341 and 342: Long Fat Pipes Networks with large
- Page 343 and 344: Example of TCP behavior 1 1. Figure
- Page 345 and 346: Hypertext Transfer Protocol (HTTP)
- Page 347 and 348: HTTP Requests request-line == reque
- Page 349 and 350: HTTP Response Codes HTTP 3-digit re
- Page 351: Server Redirect Response code 302,
- Page 355 and 356: HTTP Statistics Statistics for indi
- Page 357 and 358: HTTP Performance Problems HTTP open
- Page 359 and 360: Web Enabled Devices emWare - thin c
- Page 361 and 362: Remote Procedure Call (RPC) Two ver
- Page 363 and 364: External Data Representation (XDR)
- Page 365 and 366: NFSspy Insert a new pointer in plac
- Page 367 and 368: nfsspy Initial implementations were
- Page 369 and 370: Often there are multiple NFS client
- Page 371 and 372: NFS Mount protocol Server can check
- Page 373 and 374: NFS over TCP Provided by some vendo
- Page 375 and 376: X Window System • Client-server a
- Page 377 and 378: X was optimized for use across LANs
- Page 379 and 380: Additional tools for watching TCP P
- Page 381 and 382: Transaction TCP (T/TCP) Piggyback a
- Page 383 and 384: References [1] Information Sciences
- Page 385 and 386: Transport layer protocols • User
- Page 387 and 388: SCTP Applications • Initial goal
- Page 389 and 390: • Type SCTP Chunk 0 7 8 15 16 23
- Page 391 and 392: INIT Chunk 0 7 8 15 16 23 24 31 Typ
- Page 393 and 394: INIT ACK Chunk 0 7 8 15 16 23 24 31
- Page 395 and 396: COOKIE ECHO Chunk 0 7 8 15 16 23 24
- Page 397 and 398: Data Chunk 0 7 8 15 16 23 24 31 Typ
- Page 399 and 400: Selective Acknowledgement (SACK) Ch
- Page 401 and 402: Association Termination Two forms o
Decrease in total time to produce a response:<br />
(from Stevens, figure 13.6, Vol. 3, pg. 171)<br />
Simultaneous<br />
connections<br />
Total time<br />
(seconds)<br />
1 14.5<br />
2 11.4<br />
3 10.5<br />
4 10.2<br />
5 10.2<br />
6 10.2<br />
7 10.2<br />
Why no improvement beyond 4?<br />
• program has an implementation limit of 4, even if you specify more!<br />
• gains beyond 4 are probably small (given the small difference between<br />
3 and 4) - but Steven’s has not checked!<br />
Maguire Hypertext Transfer Protocol (HTTP) 5: 47 of 77<br />
maguire@kth.se <strong>2010</strong>.03.21 Internetworking/Internetteknik
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