? rsh/cat vs rcp/ftp over PPP?

Thread View: comp.protocols.ppp

3 messages

[T] Back to Threads [V] Tree View [G] Group Articles

3 total messages Started by Eric arnold Tue, 08 Sep 1992 21:02

#62

Author: Eric arnold
Date: Tue, 08 Sep 1992 21:02

11 lines
772 bytes

With PPP, I've noticed that "rsh" ( E.g. 
"rsh remotehost 'cat <filename' >filename", or whatever -- as long as
it is a byte stream) is about twice as fast as "ftp" and "rcp".  Is
there a way around this?  "rcp" and "ftp" are nice facilities,
especially with wrappers like "ftptool".


Thanks,
-Eric
Eric.Arnold@Sun.COM

Re: ? rsh/cat vs rcp/ftp over PPP?

#72

Author: Karl Fox
Date: Mon, 14 Sep 1992 04:57

18 lines
1516 bytes

In article <laq57rINN34i@jethro.Corp.Sun.COM> Eric.Arnold@Sun.COM
(Eric arnold) writes:

   With PPP, I've noticed that "rsh" ( E.g. 
   "rsh remotehost 'cat <filename' >filename", or whatever -- as long as
   it is a byte stream) is about twice as fast as "ftp" and "rcp".  Is
   there a way around this?  "rcp" and "ftp" are nice facilities,
   especially with wrappers like "ftptool".

I don't get quite the same results, but I do see a small but
significant speed advantage of rsh and ftp over rcp.  I turned up
debugging (I'm using Morning Star PPP, as you might guess :-), and
noticed that rsh and ftp send full size frames (1500 bytes), but rcp
sends 552-byte packets (552=20+20+512).  Both sizes are before Van
Jacobson TCP header compression.
--
Karl Fox, Morning Star Technologies                            +1 800 558 7827
1760 Zollinger Road, Columbus, Ohio 43221                      +1 614 451 1883

Re: ? rsh/cat vs rcp/ftp over PPP?

#74

Author: Vernon Schryver
Date: Mon, 14 Sep 1992 15:42

36 lines
2107 bytes

In article <KARL.92Sep14005723@crappie.MorningStar.Com>, karl@MorningStar.Com (Karl Fox) writes:
> In article <laq57rINN34i@jethro.Corp.Sun.COM> Eric.Arnold@Sun.COM
> (Eric arnold) writes:
> 
>    With PPP, I've noticed that "rsh" ( E.g. 
>    "rsh remotehost 'cat <filename' >filename", or whatever -- as long as
>    it is a byte stream) is about twice as fast as "ftp" and "rcp".  Is
>    there a way around this?  "rcp" and "ftp" are nice facilities,
>    especially with wrappers like "ftptool".
> 
> I don't get quite the same results, but I do see a small but
> significant speed advantage of rsh and ftp over rcp.  I turned up
> debugging (I'm using Morning Star PPP, as you might guess :-), and
> noticed that rsh and ftp send full size frames (1500 bytes), but rcp
> sends 552-byte packets (552=20+20+512).  Both sizes are before Van
> Jacobson TCP header compression.
> --
> Karl Fox, Morning Star Technologies                            +1 800 558 7827
> 1760 Zollinger Road, Columbus, Ohio 43221                      +1 614 451 1883

I doubt you are comparing apples to apples.  The MSS is not commonly,
at least as far as I know, directly affected or even changable by
the application.

Could your rcp target be more distant?  Causing the familiar
(Host Requirements and elsewhere) mechanisms to pick a maximum segment
size of <= 512?

Of course, `rcp` is implemented with `rsh`.  The local rcp command
does the moral equivalent of `rsh remotehost rcp ...`.  That is the source
of the ever popular "protocol screwup" error message cause by babbling
from the .cshrc on the remote machine.

Vernon Schryver,  vjs@sgi.com

Thread Navigation

This is a paginated view of messages in the thread with full content displayed inline.

Messages are displayed in chronological order, with the original post highlighted in green.

Use pagination controls to navigate through all messages in large threads.

Back to All Threads