This isn't a pure Ethernet question, but I suspect there are folks
here who have faced similar issues. In any case, if you can recommend a
better group, please do.
I'm bridging a serial HiPPI network that runs over fiber (Essential /
ODS / SBS) to a standard GigE network. Both are IP-based networks. I'm
using a spare Win2K SP3 WS machine to do this, dual 866 w/256MB.
The setup works, but is in serious need of tuning. There's no routing
software in use, just whatever 2K will do by itself.
I have a HiPPI NIC from SBS, and a quality GigE NIC, a Syskonnect 9821
V2.0, with HW checksumming and interrupt moderation.
The fiber network is running on Irix machines connected to an
Essential HiPPI switch, and by itself works very well, giving a
sustained transfer rate of 50MB/sec between any two Irix machines. It
uses an MTU of 65260, which I can't change (and wouldn't want to) and
nominally runs at 800Mb/sec.
The GigE network uses an MTU of 1500, primarily due to the need to
maintain compatibility with 100BT machines. It's a busy network, but in
general I can expect transfers of 20-30MB/s, given fast enough disks,
To further complicate things, the 2K driver for the fiber NIC allows
an MTU from 1500 to 16242, but NOT as high as the 65260 used by the rest
of the fiber network. When a connection is made from an Irix box to the
2K box, the MTU is negotiated to the lower value.
Unfortunately, the best transfer rate I have ever seen through this 2K
router is about 10 MB/s end-to-end, fiber-to-copper or the reverse. In
fact, on average it's about the same as using a 100BT all-Ethernet
connection from the Irix box. The difference is that Ethernet transfers
are steady but slow, while bridged fiber transfers are bursty, with
decided pauses that bring down the average.
With all that background (and thanks for sticking with me), is there
anything that could be done to speed this up? Am I missing something
critical? BTW, the HiPPI card is not supported under Linux, or really
anything except NT/2K/XP.