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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