I betcha a small cup of coffee that at 100MB you're either
auto-negotiating, or something is forcing full duplex. Go to your switch
and force half-duplex, or do it on the NICs. Poor performance at 100MB
with good performance at 10MB is a dead giveaway of duplexing mismatches.
If you're using a hub, *it* cannot accept full duplex by
standard. Forcing the NIC to full duplex should be impossible to a hub.
Rick
On Fri, 1 Jun 2001, Walker Traylor wrote:
> Guys,
> I'm experiencing a routing performance problem in the following
> scenario:
>
> I've got a linux firewall running ip masquerading between my PC and DSL
> connection like so:
>
> eth eth
> PC-------linux f/w----------dsl modem---Inet
>
>
> Download throughput (FTP) maxes out the DSL connection when downloading
> from the Internet to either the linux f/w or to the PC, which is good.
> Uploading directly from the linux f/w to some box on the Internet occurs
> at full throughput, which is good. The problem is that the PC only
> uploads at about half the possible throughput if the ethernet segment
> between the PC and the linux f/w is at 100Mbps. If it is forced down to
> 10Mbs, downloads occur at full throughput! The speed of the ethernet
> segment between the f/w and the dsl modem does not seem to affect
> anything.
> No frame drops are reported via ifconfig on the f/w, nor on the dsl
> modem. This has been tested with multiple ethernet cards on the f/w and
> PC, including 3com cards, Intel cards (using e100 and eepro100 drivers), a
> card using tulip drivers, and a card using via-rhine drivers. The end PC
> may be either a linux or Windows box (both exhibit the same behavior.)
> This behavior is exhibited on a Redhat 7.0 box using several version of
> 2.2.x kernel ( all were somewhere between 2.2.14 - 2.2.18.) This behavior
> also is exhibited on a Redhat 7.1 box running the stock 2.4.2-2 kernel
> using the ipchains compatibility module.
>
> What gives? I've seen a few old thread with similar problems (they can be
> dug up if someone needs them) but nobody ever has a response.
>
>
> Thanks,
> --Walker
>
>
>
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This archive was generated by hypermail 2b29 : Thu Jun 07 2001 - 21:01:14 EST