Matt, John: I would just as soon use 10-100Mbit, but the firmware we have developed uses the 10 gbe port. I understand this to be fairly fundamental in that the CASPER libraries allow simpler interfacing of the memory to the 10 gbe than to the 100 Mbit. My recollection of the details is fuzzy (and I'm not a firmware engineer) but I don't see this aspect of the design as likely to change. So I think that we're stuck going with N 10 gbe ports for N boards. We have unsolved problems to solve instead.
I'll poke around for cheaper switches. Matt: are you using the Zarlink CX4-optical-CX4 cables with the Myricom card? That seems to contradict John's assertion that the Myricom has trouble driving transceivers. Tom On Thu, Aug 5, 2010 at 3:41 PM, Matt Dexter <[email protected]> wrote: > In the past many switch vendors advertised performance they couldn't > actually provide in our applications. > > Yes there are XFP to CX4 transceivers. I'm no expert in > such things but > we are talking to a number of vendors now about switches w/ > 48,64,..hundreds of ports and they talk about many such > adapter options. So far most like SFP+ or QSFP relative > to the long list of interface options. > > The CASPER hardware limit is much less than the CX4 specification's > 15m limit for copper wiring. > At ATA we have in use the Zarlink fiber optic cables w/ CX4 > connectors for 5m, 10m and 15m applications. > See the equipment_cables page for more information. > > Matt > > On Thu, 5 Aug 2010, Tom Downes wrote: > >> No. >> >> Believe it or not I spent a long time looking everywhere but the >> Casper wiki. Should have thought of that because that's where we got >> the Myricom card from. >> >> Those listed are at the higher end of the price range I've seen. Looks >> like ~$10k is the amount I should be prepared to spend. >> >> Am I right to interpret the XFP ports as something I could convert CX4 >> to use with a transceiver? >> >> Tom >> >> On Thu, Aug 5, 2010 at 3:21 PM, Matt Dexter <[email protected]> wrote: >>> >>> Hi Tom, >>> >>> were you aware of these ? >>> http://casper.berkeley.edu/wiki/Recommended_10_GbE_Hardware >>> http://casper.berkeley.edu/wiki/Equipment_Cables >>> Matt Dexter >>> >>> On Thu, 5 Aug 2010, Tom Downes wrote: >>> >>>> Casper-folks: >>>> >>>> Hoping to short-circuit a fair amount of research here in the hope >>>> that someone has had to do this already. I'll soon be looking to >>>> connect 10-20 ROACH boards by 10 gbe to a data acquisition >>>> computer(s). >>>> >>>> It seems like the smartest way of doing that is getting a 16-port >>>> switch or potentially two 8-port switches. But the 10 Gbe port on the >>>> ROACH seems to be CX4 which I take to be a less popular connector >>>> variety. >>>> >>>> What kind of switches have ROACH users out there used to connect up a >>>> bunch of boards? Are there switches out there to convert CX4 to >>>> something with a reach longer than the 15m Wikipedia quotes as the >>>> limit of CX4. 15m is very borderline for our needs. >>>> >>>> The prices seem to vary widely. We do not need network admin tools or >>>> anything fancy. In fact our data rates could probably go over 10Mb >>>> cabling, but the 10Gbe interface of the ROACH is more convenient from >>>> the firmware perspective. This is more of a multiplexer than a switch. >>>> >>>> Tom >>>> >>>> >>> >>> >> > >
