Jak je to mozne?

[Jan Prikryl]

Dobry den vsem,

narazil jsem na zajimavou anomalii, kterou nechapu - mozna to neni
anomalie, ale nechapu to tak jako tak:

Jsem ve Vidni a pretahuji si ruzne kusy pocesteni pro SGI a Linux ze
serveru na CESNETu. Z Prahy jsem byval zvykly, ze nejrychlejsi server
je Sunsite (byl jsem na FEL a tedy na PASNetu) a ta by teoreticky mela
byt i nejrychlejsi odsud (podle meho nazoru), protoze je bliz a
rychleji pripojena k lince Praha-Mnichov (ma vesti pocet hopu, ale to
by snad nemuselo vadit). Ve skutecnosti to ale vychazi zhruba 2x
rychelji na FTP server Masarykovy univerzity v Brne.

Ping pro oba stroje (neni asi moc smerodatny) rika toto:

| --- sunsite.ms.mff.cuni.cz ping statistics ---
| 30 packets transmitted, 19 packets received, 36% packet loss
| round-trip min/avg/max = 156.9/271.9/352.6 ms

a

| --- anxur.fi.muni.cz ping statistics ---
| 30 packets transmitted, 19 packets received, 36% packet loss
| round-trip min/avg/max = 199.5/346.9/574.2 ms

Pocet hopu je 12 (Praha) resp 11 (Brno), a kdyz si pustim FTP,
dopadne to kupodivu pro Sunsite takto:

| 200 PORT command successful.
| 150 Opening BINARY mode data connection for patch-2.0.3.gz (104581 bytes).
| 226 Transfer complete.
| 104581 bytes received in 325.13 seconds (0.31 Kbytes/s)
                           ^^^^^^          ^^^^
a pro Brno takto:

| 200 PORT command successful.
| 150 Opening BINARY mode data connection for patch-2.0.3.gz (104581 bytes).
| 226 Transfer complete.
| 104581 bytes received in 131.07 seconds (0.78 Kbytes/s)
                           ^^^^^^          ^^^^
Coz se mi zda divne. Mohl by mi nekdo rict, cim to muze byt zpusobene?
Fragemtnaci na ATM (kratsi pakety, 64B pingy, sjou rychlejsi do Prahy,
delsi - FTP - do Brna) ?

Dekuji.

-- JP

-------------------------------------------------------------------------
               Jan Prikryl <prikryl at cg.tuwien.ac.at>
         http://www.cg.tuwien.ac.at/staff/JanPrikryl.html
         Institute of Computer Graphics and Visualisation
              Vienna Institue of Technology, Austria
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