[S] DE500: 100BaseTX worse that 10BaseT?

From: <pgouffon_at_charme.if.usp.br>
Date: Tue, 27 May 97 10:01:21 -0300

Hi,
        Thanks to
                Matt Thomas <thomas_at_lkg.dec.com>
                Dirk Grunwald <grunwald_at_foobar.cs.colorado.edu>
                "Macdonell, Dennis" <DennisMacdonell_at_auslig.gov.au>
                Tom Ozanich <txo_at_esca.com>
                Harald Lundberg <hl_at_tekla.fi>
                Brian Sheehan <sheehan_at_scripps.edu>
                "C.J. Bol" <bol_at_GisSrv.IenD.WAU.NL>
                Hannu Visti <visti_at_som.fi>

        The DE500 was set as ew*0_mode fastFD and it seems the the hub does
not support full duplex. Indeed during the boot sequence, there is a mention
to that: "tu1: console mode: selecting 100BaseTX _(UTP) port: full duplex:
no link", which I interpreted wrongly as the autonegociation had reached
the conclusion that the interface must run at 100, half duplex.

        The consensus from the replies was to force a 100MB/s half duplex
by issuing a

                ifconfig tu* speed 100

which I did and now I get ftp and NFS transfers above 3.4MB/s, limited by
disk speed, I think.

        There were suggestions to use a switch rather than a hub. This may be
a plan for the future but currently the hub is enough for the traffic we have
to handle.

        The question is below, the answers are not, to save bandwith, but I
can send them to anyone requesting them. Once again, thanks for the answers.

                                                Philippe

--------------------------- Original question ---------------------------------
Hi

        I have seen a message about this problem a couple of days ago but
no answers nor summaries so I need to ask an already asked the question:

I have installed a Fast Ethernet card (DE500 - DECchip 21140-AA: Revision: 1.2)
on a 2100 4/275 and two 2000 4/200 systems (after a firmware update that comes
with the V3.2G kit) and then upgraded to DU 3.2G. All the 3 systems are
connected to a 3Com 100MHz OfficeConnect hub which in turn is connected to a
Fast ethernet switch to the rest of our LAN.

        Each system sees the rest of the network and each other too.
I can copy data at a rate over 700KB/s to or from any system on our net from or
to any of these servers at any time. But... if I copy data between any of these
three servers, I get anything between 57KB/s (at midnight, very low traffic) up
to 130KB/s (best rate sofar). I was expecting several MB/s. I got a message on
the console about "silo buffer underflow, increasing to 256" that I remember
having read in this list a couple of days ago. So my question:

        What is the secret to use a DE500 up to its speed? Should I step back
to an effectively much faster regular ethernet card? I am getting constant NFS
errors, for example, but no errors recorded in the error log.

                                                        Philippe

--------------------------------------------------------------------------------
PHILIPPE GOUFFON |
Instituto de Fisica | INASMUCH as three quarters of the earth's
Universidade de Sao Paulo | surface is water and only one fourth is land
Caixa Postal 66318 | the good Lord's Intentions are very clear:
05389-970 Sao Paulo |
Brazil | A man's time should be divided:
                            |
Tel: (55)(11)818-7045 | three fourths for sailing and one fourth for work.
Fax: (55)(11)818-6832 |
email: pgouffon_at_if.usp.br |
--------------------------------------------------------------------------------
Received on Tue May 27 1997 - 15:25:41 NZST

This archive was generated by hypermail 2.4.0 : Wed Nov 08 2023 - 11:53:36 NZDT