Debian - zpomalovani scp

[Jan Ptacek]

Pekny den,
mam problem s scp na Debianu 3.0, jadro 2.4.18, OpenSSH_3.4.p1, sitova 
karta 3c905C-TX-M. Jedna se vlastne o 2 problemy (nevim, zda spolu 
souvisi).

1. Pri kopirovani vetsiho souboru (pro testovani pouzivam soubor o  
velikosti cca 40MB) z nebo na debian dochazi ke zpomaleni prenosu. Jako 
klienta jsem zkousel RedHat7.2 a QNX6.2.1 (karty rovnez 3c905), priznaky 
jsou vzdy stejne. Zacne se kopirovat na bezne rychlosti (cca 5-6MB/s), 
priblizne v polovine se vsak prenos skoro zastavi, par sekund roste 
progress bar po jednotlivych procentech, a pak zase vse bezi jak ma. Ve 
vystupu z tcpdump se behem toho zpomaleni vyskytuji serie nekolika ACK 
paketu po sobe, napr.:

14:30:48.437460 redhat.1056 > debian.ssh: . 28203279:28204727(1448) ack 
18608 win 8832 <nop,nop,timestamp 309293 852930> (DF) [tos 0x8]
>>>>>>
14:30:48.476874 debian.ssh > redhat.1056: . ack 28204727 win 0 
<nop,nop,timestamp 852934 309293> (DF) [tos 0x8]  
14:30:48.635125 debian.ssh > redhat.1056: . ack 28204727 win 15928 
<nop,nop,timestamp 852949 309293> (DF) [tos 0x8]
>>>>>>
14:30:48.636825 redhat.1056 > debian.ssh: . 28204727:28206175(1448) ack 
18608 win 8832 <nop,nop,timestamp 309313 852949> (DF) [tos 0x8]
14:30:48.636943 redhat.1056 > debian.ssh: . 28206175:28207623(1448) ack 
18608 win 8832 <nop,nop,timestamp 309313 852949> (DF) [tos 0x8]
14:30:48.637069 redhat.1056 > debian.ssh: . 28207623:28209071(1448) ack 
18608 win 8832 <nop,nop,timestamp 309313 852949> (DF) [tos 0x8]
14:30:48.637192 redhat.1056 > debian.ssh: . 28209071:28210519(1448) ack 
18608 win 8832 <nop,nop,timestamp 309313 852949> (DF) [tos 0x8]
14:30:48.637317 redhat.1056 > debian.ssh: . 28210519:28211967(1448) ack 
18608 win 8832 <nop,nop,timestamp 309313 852949> (DF) [tos 0x8]
14:30:48.637448 redhat.1056 > debian.ssh: . 28211967:28213415(1448) ack 
18608 win 8832 <nop,nop,timestamp 309313 852949> (DF) [tos 0x8]
14:30:48.637449 redhat.1056 > debian.ssh: P 28213415:28213959(544) ack 
18608 win 8832 <nop,nop,timestamp 309313 852949> (DF) [tos 0x8] 
>>>>>>
14:30:48.676711 debian.ssh > redhat.1056: . ack 28213959 win 6696 
<nop,nop,timestamp 852954 309313> (DF) [tos 0x8] 
14:30:48.848004 debian.ssh > redhat.1056: . ack 28213959 win 20272 
<nop,nop,timestamp 852971 309313> (DF) [tos 0x8]
14:30:49.338519 debian.ssh > redhat.1056: . ack 28213959 win 50680 
<nop,nop,timestamp 853020 309313> (DF) [tos 0x8]
>>>>>>
14:30:49.354830 debian.ssh > redhat.1056: P 18608:18656(48) ack 28213959 
win 50680 <nop,nop,timestamp 853021 309313> (DF) [tos 0x8]



2. Pri kopirovani z Windows (98 i XP, opet karty 3c905) pomoci pscp bezi 
cely prenos pomalu, cca 80-100kB. Kousek z tcpdump vypada takto:

15:22:27.279560 winxp.3023 > debian.ssh: P 587601:589061(1460) ack 11208 
win 63628 (DF)
15:22:27.279574 debian.ssh > winxp.3023: . ack 589061 win 62780 (DF) [tos 
0x8]
15:22:27.279561 winxp.3023 > debian.ssh: P 589061:589293(232) ack 11208 
win 63628 (DF)
15:22:27.279701 winxp.3023 > debian.ssh: P 589293:589345(52) ack 11208 win 
63628 (DF)
15:22:27.280720 winxp.3023 > debian.ssh: P 589345:590805(1460) ack 11208 
win 63628 (DF)
15:22:27.280733 debian.ssh > winxp.3023: . ack 590805 win 62780 (DF) [tos 
0x8]
15:22:27.280721 winxp.3023 > debian.ssh: P 590805:590985(180) ack 11208 
win 63628 (DF)
15:22:27.280855 winxp.3023 > debian.ssh: P 590985:591037(52) ack 11208 win 
63628 (DF)
15:22:27.317179 debian.ssh > winxp.3023: . ack 591037 win 62780 (DF) [tos 
0x8]
15:22:27.317523 winxp.3023 > debian.ssh: P 591037:592233(1196) ack 11208 
win 63628 (DF)
15:22:27.317571 debian.ssh > winxp.3023: . ack 592233 win 62780 (DF) [tos 
0x8]
15:22:27.317919 debian.ssh > winxp.3023: P 11208:11276(68) ack 592233 win 
62780 (DF) [tos 0x8]
15:22:27.318175 winxp.3023 > debian.ssh: P 592233:592285(52) ack 11276 win 
63560 (DF)
15:22:27.319602 winxp.3023 > debian.ssh: P 592285:593745(1460) ack 11276 
win 63560 (DF)
15:22:27.319618 debian.ssh > winxp.3023: . ack 593745 win 62780 (DF) [tos 
0x8]
15:22:27.319603 winxp.3023 > debian.ssh: P 593745:593977(232) ack 11276 
win 63560 (DF)
15:22:27.319745 winxp.3023 > debian.ssh: P 593977:594029(52) ack 11276 win 
63560 (DF)
15:22:27.320753 winxp.3023 > debian.ssh: P 594029:595489(1460) ack 11276 
win 63560 (DF)

Prenosy Windows->RedHat, QNX->RedHat, RedHat->QNX funguji normalne.

Diky za nasmerovani,
j.