Effective bandwidth reduction over WAN

From: Eric Meijer (res0t122_at_verizon.net)
Date: 07/30/05

  • Next message: Eric_G_Halcik_at_keybank.com: "strange error message when pushing a file using scp" 
    Date: Fri, 29 Jul 2005 20:40:49 -0700
To: <secureshell@securityfocus.com>

    To SSH mailing list:

     

     

    I have a somewhat unusual question. I do not know if this issue is truly a
    bug or just a feature of the protocol.

     

    I have two sites that are distantly connected to each other via a DS3 WAN.
    When we tried to replace FTP with SCP or SFTP we ran into throughput
    problems. We then set up a test in our lab to see if we could isolate the
    factor that was impacting throughput. This test setup was composed of two
    nodes hooked up through a WAN emulator. They were connected using Gigabit
    Ethernet, but the rate was throttled back to 45 mbps (DS3 rate). All of the
    testing used an MTU of 1500 and files sizes of 10 MB, 100Mb, 1 GB, and 5 GB.
    We ran FTP tests with the same setup for a baseline. For SCP and SFTP we
    tried each of the three encryption algorithms (3-des, arcfour, & blowfish).
    We then varied the WAN latency. We are using the latest version of the
    Portable SSP for Solaris. The OS is Solaris 8.

     

    The results were

     

    0 latency FTP - Ave. 39.5 mbps SCP - Ave. 39.4 mbps SFTP - Ave.
    38.8 mbps

    60 millisec FTP - Ave. 37.7 mbps SCP - Ave. 2.9 mbps SFTP -
    Ave. 2.9 mbps

    100 millisec FTP - Ave. 33.0 mbps SCP - Ave. 2.0 mbps SFTP - Ave.
    1.8 mbps

     

    Can anyone tell me why the throughput of SCP and SFTP drop so drastically
    when we try to use SSP protocols over a WAN?

     

    Eric Meijer

  • Next message: Eric_G_Halcik_at_keybank.com: "strange error message when pushing a file using scp"

    Relevant Pages

    • Re: Effective bandwidth reduction over WAN
      ... This is probably caused by the way SSH multiplexes the TCP stream. ... > I have two sites that are distantly connected to each other via a DS3 WAN. ... > factor that was impacting throughput. ... > 38.8 mbps ...
      (SSH)
    • Re: Cisco 2651XM high cpu usage 12.4(25b)IPBASEK9
      ... Could I expect 14mbit full throughput, when downloading from 2x WIC ADSL ... Mbps _ PPS. ... is limited by packet rate, packet size in effect does not matter. ...
      (comp.dcom.sys.cisco)
    • Re: how to increase through put of LAN to 1GB
      ... i learn that my LAN throughput is like 200 to 300 Mbps which is quite ... the 1000 Mbps throughput. ... To UNSUBSCRIBE, email to debian-user-REQUEST@xxxxxxxxxxxxxxxx ...
      (Debian-User)
    • RE: query on firewall throughput.....
      ... if I have a 100 mbps network card in my workstation and I ... might be the firewall if it only has 10 mbps throughput. ...
      (Security-Basics)
    • Re: Effective bandwidth reduction over WAN
      ... Eric Meijer wrote: ... > I have a somewhat unusual question. ... > could isolate the factor that was impacting throughput. ... mbps ...
      (SSH)