06-09-2005 07:17 AM - edited 03-09-2019 11:32 AM
Dear all,
I'm using a cisco VPN concentrator 3020. Currently, i've some FTP throughput problems. Indeed, my FTP data rate, through a VPN connexion, is about 30KB/s. Without the VPN connexion, i have a data rate of 400KB/s.
The TCP MMS size is set to 1280 both on the FTP client and on the FTP server.
Does anybody have a solution ?
Thanks.
Regards,
David Roy.
06-12-2005 07:44 AM
There may be an path mtu or a link speed negotiation issue. For path mtu to work, icmp unreachable messages can't be blocked by black-hole routers and the echo and echo-reply must be sent end-to-end. So if there is any device that blocks those messages, then the ftp connection is probably using 512-byte payloads instead of 1280 byte payloads.
If the 3020 or the ftp server's interfaces are set to autonegotiate, then try explicitly setting the speed and duplex on those interfaces as well as the switch ports that they connect to. You may have a similar issue on the client end, though you may not be able to do much in the case of remote clients - however you can try to have the remote user do an explicit speed/duplex setting on the client's NIC.
Let me know what you find.
06-16-2005 03:08 AM
The FTP server was in auto mode and my switch in duplex full. I configured duplex full on my FTP server and all work well.
Thanks.
Regards.
David.
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