Hello.
As far as I can tell, www.rfc-editor.org doesn't support TCP window
scaling. It also doesn't support ftp on its IPv6 address:
swmike@uplift:~$ telnet -4 www.rfc-editor.org 21
Trying 64.170.98.47...
Connected to rfc-editor.org.
Escape character is '^]'.
220 "FTP Server Ready"
quit
221 Goodbye.
Connection closed by foreign host.
swmike@uplift:~$ telnet -6 www.rfc-editor.org 21
Trying 2001:1890:126c::1:2f...
telnet: Unable to connect to remote host: Connection refused
14:00:38.045593 IP (tos 0x10, ttl 64, id 33826, offset 0, flags [DF],
proto TCP (6), length 60) xxx.xxx.xxx.xxx.36300 > 64.170.98.47.21: Flags
[SEW], cksum 0xc541 (correct), seq 1822128746, win 5840, options [mss
1460,sackOK,TS val 3080584776 ecr 0,nop,wscale 7], length 0
14:00:38.224653 IP (tos 0x0, ttl 57, id 0, offset 0, flags [DF], proto TCP
(6), length 56) 64.170.98.41.21 > xxx.xxx.xxx.xxx.36300: Flags [S.], cksum
0x9c17 (correct), seq 831902177, ack 1822128747, win 5792, options [mss
1460,sackOK,TS val 332539598 ecr 3080584776], length 0
I get 124 kilobyte/s when I download
<ftp://ftp.rfc-editor.org/in-notes/tar/RFC-all.tar.gz>. That seems quite
slow by todays standards. Since I have 179ms delay, it doesn't really hit
me as indicating 16 or 32 kilobyte window size, but somewhere in between.
www.ietf.org doesn't seem to support TCP window scaling either:
13:58:13.565917 IP xxx.xxx.xxx.xxx.41603 > 12.22.58.30.80: Flags [SEW],
seq 3844537042, win 5840, options [mss 1460,sackOK,TS val 3080548657 ecr
0,nop,wscale 7], length 0
13:58:13.746501 IP 12.22.58.30.80 > xxx.xxx.xxx.xxx.41603: Flags [S.], seq
4206253981, ack 3844537043, win 5792, options [mss 1460,sackOK,TS val
357513706 ecr 3080548657], length 0
Any specific reason for this? My host connects with "wscale 7".
--
Mikael Abrahamsson email: swm...@swm.pp.se
