Re: Max Devices on ethernet adapters -- MIDRANGE-L

Pat,

Yer settin' me up here ;-)

Pat Barber wrote:

Okey Dokey... (I understand the "depends" concept very well)

> You said Hubs will kill you ... Why ???

Hubs work like Kindergarden. Every kid screams loud enough for everyone in the room to hear. All at once. Constantly. Two or there or four kids, OK but get enough kids in the room and Nothing gets done except a mess gets made. I know this. My daughter tells me about it a couple times a week. :-)

> If a hub will kill you, how come a switch won't ???

Switches work more like a PBX. If I need to communicate to you I call You. We communicate and then hang up. Nobody else hears us. Others can be calling simultaneously. Many conversations can go on at once with no problem. The difference is the 'calls' last only as long as needed for a packet to get through, the next 'call' can be a milli-second or less later. Throughput is much better because I only hear what I need to hear and so does every other device on the network. (I'm ignoring broadcasts for the sake of this discussion)

By the way, I don't think processor speed has much to do with the ethernet speed issues but that's just me. Any processor worth it's salt in the last 8 years could handle a billion ethernet requests standing on it's head.

Again it Depends. What request are you making to said processor? If it's a complex SQL request over million record tables then just a few requests sends the processor to work for a long time. If it's FTP then it don't take much processor to send back a big bunchfulla packets.

Full Duplex according to all the books I have ever seen or read requires 4 wires. Don't most garden variety ethernet wiring setups use 2 wires ???

Two PAIRS! If yer usin' ethernet yer usin' 2 pair. If yawanna get to GbE (Giga Bit) then you need FOUR pairs (all 8 wires.) and it better be good Cat5 done right too. And didja know there are two flavors of GbE? The difference with Full Duplex is that with full you have a smart device on each end of the wire and Only one device on each end. So "A" has it's transmit pair conencted directly to "B's" recieve pair and vice versa. If they agree, then they can each speak simultaneously theoretically doubling bandwidth. Of course almost no one transmittes the same amount as they recieve so it's in theory only, but it certainly does help.

If you were doing a BRAND NEW installation today and there no existing network wires, what would you have on the back of the box and all points forward for the connections ???

I make it easy...(810 with 100 devices 80 pc's 20 printers

all ethernet attached. All in the same building. To make it
interesting, 5 of the printers are 1000lpm and are used 70%
of the day.

Cat 6 or better wire everywhere. SM Fiber betweeen all wire closets. 100Mb adaptors on most stuff, Gb adaptors on my servers, iSeries included. Gb switches in the computer room with 10Gb uplinks and 100Mb switches in the closets with Gb fiber uplinks to the computer room.

To make it more interesting, NO tech people ever at this site.

Lock the doors to the closets.

- Larry

(this is just for fun so don't take this serious)

Larry Bolhuis wrote:

Pat,

Andy is right. THe true answer is "It Depends." On:

Realisticaly though If you are on V5R2 I would absolutely get a second adaptor and configure them to be redundant and allow OS/400 to load balance them. It's really quite simple, and it avoids many many problems with virtually *zero downside.

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