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Hello Jay,

Am 25.08.2022 um 17:59 schrieb Jay B <orcljsb@xxxxxxxxx>:

thank you all for the advice and guidance.

You're most welcome!

I am going to try to buy two baluns that will have been tested to communicate with each other to (eventually) eliminate the baluns as a potential problem.

Another option might be to buy a more or less short run of readymade Twinax cable.

Is it possible to verify that the 2720 card is working?


Connect the machine to your network, or a computer, *before* IPL. Use a packet sniffer like Wireshark to see what it sends out do deduce its IP address. Configure a (temporary) network connection on your main Computer accordingly. As long as you choose an IP address next to the one you've seen, the network mask shouldn't matter. If you've seen an RFC1918 address, you can safely assume a /24 netmask. Since you're not going outside of that network segment, you can leave the gateway entry blank. This in turn enables you to use a 5250 client to connect to the machine.

Next step is to see if the (most likely unknown) QSECOFR password is still at default QSECOFR. Depending on the password level, it might be case sensitive or not. Use all caps to be safe. If not, stop trying. You'll lock the user profile, and device (if the system defaults haven't been changed) and this change is *permanent*. You can still log on with a locked QSECOFR in manual mode, from console.

If the machine is running and looses the Ethernet Link, the line will go into error state more or less quickly and (by default) not recover by itself. You need to use whatever convenient means to force a re-IPL (because no console).

If you're in, you can do a dsphdwrsc *cmn to look which components are recognized by the system. This is no proof that the card is completely working OK, just that it's initialized by the OS.

You can enter SST (strsst) for more hardware fun. Depending on the OS release running you may or may not be asked about the DST password. This in turn is also QSECOFR by default. Depending on the password level, it might be case sensitive or not. Use all caps to be safe.

Start a service tool, go to the hardware service manager and browse around if you like. I have seen the possibility to see and change the current console connection in SST, but I can't find it. Maybe you can change this setting only after switching the running machine to manual mode (no IPL required), you can do this in DST only (on console, after a power on in manual mode, so not useful here) or my V4R5 is just too old.

I removed the card and i'm pretty sure the front panel SRC output was the same in both "N" and "M" settings.

I'm not sure if removing the card makes any difference, because the *console* wasn't found. The reason (no terminal on address 0, or no controller detected) is secondar.

I may have to do this again to refresh my memory. I was hoping the machine would display a result code that the twinax adapter was missing from slot C08 when it was not in the pci slot. I wish there was a way to rule out whether the 2720 is detected and operating, or not, when installed in the server.

I think, it's much less hassle to rule out a cabling issue. May I ask about your coarse location? Maybe there's someone nearby who can lend you known to work cards, Y-adapters, a terminal, and cables to more efficiently rule out the main culprit.

The machine came with a 2722 card with the DB25 connector, but I don't have a 8-port block or cable to connect to the DB25.

Keep it. Maybe you'll stumble over a garage full of terminals one day, and then you can look out for an 8-port brick and much more Baluns, or Twinax cables. :-)

I reached out to CLI about termination and the support team said the CLI 5476 was self-terminating. The terminal has a DB15 Y cable with 2 female twinax sockets. I have a twinax terminator. I could try connecting the terminator but perhaps my baluns are broken.

Not necessarily broken but maybe use different pinouts each. Did you have a closer look to verify the pins are reasonably clean and straight? And, on the Twinax side, come out "far" enough?

I have one RJ45 balun that ends in a 4 (45-4), and two that end in a 5 (45-5). I assume this is the polarity of pins 4 and 5.

Please get yourself a connection tester. :-) They're cheap to have and you'll find more use cases for it once you have one. Better be sure than assume.

Is it possible to use a crossover ethernet cable with one 45-4 and one 45-5 balun?

No. Because crossover means that individual pairs are crossed with each other. It doesn't mean that the polarity of one pair is crossed. Usually, a fully connected Ethernet cable has 1-2, 3-6, 4-5, and 7-8 pairs 1:1 on both sides. A crossover cable crosses 1-2 with 3-6, and 4-5 with 7-8.

Or, do I just simply have to have two baluns that both end with the same digit (both being 45-4 or 45-5)?

I don't know. Without a connection tester, or force-open the baluns to see the wires, it's all guesswork.

:wq! PoC

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