FTP speed on a half c1802

Unanswered Question
Nov 12th, 2009


I got curious problem on my c1802.

I updated IOS from 12.4.15t6 to 15.0.1M and then back to 12.4.24.t2 and meny times I change ADSL firmware too.

Noticed that my original ADSL FW 3.0.14 was in new IOS 15 builds useless because established connection was only 7Mb instead of 15Mb in down so I try newer firmware 4.0.3, 13, 15 and still same problem, then I downgrade IOS to 12.4.24T2 and still same, I find out that I must use 3.0.10 firmware and got full line speed 15Mb/766kb all newer had hald DL speeds. Now I running on 12.4.24T2 and 3.0.10 FW and have problem with downloading files using FTP. It starts about full speed 1.0-1.4MB/s and skips to 300KB and up down and finaly it after 5 sec leave about 600KB/s, measured from my ISP FTP server on Filezilla client. The downloading using HTTP not have so big fluctuation and run on 1MB - 1,1MB/s

ATM MTU was 1452 and BVI was 1412 I changed to 1492 / 1452

Looks like some buffer overflow.

Thanks for any help.

I have this problem too.
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locus2007 Fri, 11/13/2009 - 09:12

Ok thanks I will try setup 1500 but I thing that this wil not be main reason of problem

Paolo Bevilacqua Fri, 11/13/2009 - 09:14

Anyway for the router, FTP or HTTP is just the same so that is not a router problem neither.

Paolo Bevilacqua Fri, 11/13/2009 - 09:33

There is no "brutal" qualifier in TCP-based network protocols. I assume you are not in this profession.

locus2007 Fri, 11/13/2009 - 09:54

I know and hope that you will understand that.

We not discuss someones profesionality but my problem.

Both can confirms that ftp is more than http in traffic needs

locus2007 Fri, 11/13/2009 - 10:14

I tryed my ISP FTP and ftp of university in my city and still same.

Paolo Bevilacqua Fri, 11/13/2009 - 10:17

It is common practice to limit the speed of a single session of FTP servers, do you know that ?

Again: FTP and HTTP are the same for the router.

You should instead fix the MTU that was changed for no reason.

locus2007 Fri, 11/13/2009 - 10:21

Not by my ISP

MTU was 1452 but not know why so I changed to 1492 by cisco document about PppoE

Paolo Bevilacqua Fri, 11/13/2009 - 10:24

Do you work for the ISP so you know for sure how their servers are configured ?

Do you have PPPoE ? If so, you should not have BVI for DSL.

Anyway, the point stays the same: If FTP is slower than HTTP, that is not router fault.

locus2007 Fri, 11/13/2009 - 10:48

Not but have friend there

pppoe yes bvi bridge because have 1802w and wifi is bridged to lan

locus2007 Fri, 11/13/2009 - 11:45

Thank you will make more investigation but any help welcommed

locus2007 Mon, 11/16/2009 - 09:57

I have done some testing and found that 1802 is really at half speed.

When I connected other ADSL modem FTP works about 1,2-1,4MB/s when I conected this modem to 1802 FE0 port speed was same 1,2-1,4MB/s, when usind 1802 integraded ADSL speed is on half. This testing was done on basic NAT,Routing and basic FW. What can be problem is that 1802 is more sensitive to not good qulity of ADSL line or something else.

Some ideas?


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