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3com 3870 (3CR17451-9) Console Connection

3com 3870 (3CR17451-9) Console Connection

3com 3870 (3CR17451-9) Console Connection

(OP)
I just bought two 3Com 3870 switches (3CR17451-9) and am attempting to connect to them via the Console port. According to the manual, I should use a RJ45 converter cable pinned out this way:

RJ45 DB9F
4 (DTR) ------------ 1 (DCD)& 6 (DSR)
3 (TxD) ------------ 2 (RxD)
2 (RxD) ------------ 3 (TxD)
8 (CTS) ------------ 7 (RTS)
5 (Gnd) ------------ 5 (Gnd)
6 (DSR)& 1 (DCD) --- 4 (DTR)
7 (RTS) ------------ 8 (CTS)

but the manual goes on to say that I should use this converter cable along with a null modem cable. They show pinouts for the null modem cable, too. The confusing thing is that the null modem cable they show is an RJ45 to DB25 so obviously, those two cannot be connected together.

I think they mean I should use one or the other but when I construct an RJ45 to DB9 converter cable (as shown above, pinouts double checked) I cannot connect to either switch via HyperTerminal on a PC with a 9 pin comport.

Does anyone have any advice? Thanks

RE: 3com 3870 (3CR17451-9) Console Connection

CHeck the speed - I have a recollection of some of these switches using 19200. It was written on the face plate from memory.

I can't remember ever having issues consoling onto them, so that tells me they used the Cisco console lead, not the procurve one.

RE: 3com 3870 (3CR17451-9) Console Connection

(OP)
Yes, you are correct about the speed. I am attempting 8, none and 1, no flow control at 19200.

RE: 3com 3870 (3CR17451-9) Console Connection

(OP)
Hmmmm, when I power the switch, I do see the unit performing several POST and opening image files, entering provisioning... then a blank screen with no login prompt.

Anyone?

RE: 3com 3870 (3CR17451-9) Console Connection

Ah, so you see some output. Your console connection is OK.

Did you by any chance interrupt a firmware upgrade before it had finished?

Have you tried factory-resetting it?

I don't know with 3COM whether a corrupted OS can be replaced in the field. Pretty sure with Nortel or Procurve they used to say you'd have to send it back to the factory to be reflashed.

RE: 3com 3870 (3CR17451-9) Console Connection

Maybe you can try to break into the boot sequence and boot it off a different file, if there is one?

RE: 3com 3870 (3CR17451-9) Console Connection

(OP)
I've tried several keystrokes to break into boot sequence and otherwise communicate with both units using HyperTerminal, then Tera Term with multiple settings for serial communication. Neither seem to respond at all. Here is a link to several backdoor keystrokes I've been attempting:

http://etherhack.wikia.com/wiki/3Com_3870

The only settings I've had success with (ie.: I at least see the boot up sequence) is 8, None, and 1, No Flow control and 19200. Local Echo and Transmit CR & LF selected allows me at least type something but when they are selected I see garbage on boot up. If these two settings are turned off, I do see intelligible boot info.

Also, making the cable as indicated in the 3Com manual does NOT work at all in that I see no boot sequence with it. The cable I made which seems to work (at least showing the boot sequence) was DCD to DCD, RX to TX, TX to RX, DTR to DSR, DSR to DTR, GND to GND, RTS to CTS and CTS to RTS. (This is very similar to the suggested 3com cable except they DO NOT connect DCD to DCD. On theirs, they put DCD with DSR and connect that to other unit's DTR. This is done in both directions as I indicated in my original post.)

So far as interrupting a firmware update, I don't know as I've just purchased these units used. I know I have not attempted a firmware update.

So far as resetting to factory, I don't think that can be done without FIRST some sort of commnication with the unit. ie.: there is no reset button you can hold in during power up.

I do see in the manual where the unit can be administered via a web browser but that, of course, requires knowing the IP and I do not see it leasing a DHCP IP on my server. I assume it will not attempt to lease an IP unless the IP's IP has not been manually set.

Incidentally, this is the boot info:

Äį¯(Ì
Hardware EPLD 1.01

Image Loader 3.1.0.1
Loading Diagnostic Image File : Sw3870_diag_V3_1_0_2.bix

Diagnostics 3.1.0.2
User Mode

--- Performing Power-On Self Tests (POST) ---
UART Loopback Test ........... PASS
DRAM Test .................... PASS
Timer Test ................... PASS
PCI Device 1 Test ............ PASS
I2C Bus Initialization ....... PASS
Switch Int Loopback Test ..... PASS
Crossbar Int Loopback Test ... PASS
Fan Speed Test ............... PASS
Done All Pass.
------------------ DONE ---------------------

Äį¯(Ì
Loading Runtime Image File : op1.bix
Runtime 3.0.10.0

Expected module version: 3.0.10.0
PCI unit 0: Dev 0x5690, Rev 0x03, Chip BCM5690_A2, Driver BCM5690_A0
PCI unit 1: Dev 0x5690, Rev 0x03, Chip BCM5690_A2, Driver BCM5690_A0
PCI unit 2: Dev 0x5690, Rev 0x03, Chip BCM5690_A2, Driver BCM5690_A0
PCI unit 3: Dev 0x5690, Rev 0x03, Chip BCM5690_A2, Driver BCM5690_A0
PCI unit 4: Dev 0x5670, Rev 0x02, Chip BCM5670_A1, Driver BCM5670_A0
PCI device BCM5690_A2 attached as unit 0.
PCI device BCM5690_A2 attached as unit 1.
PCI device BCM5690_A2 attached as unit 2.
PCI device BCM5690_A2 attached as unit 3.
PCI device BCM5670_A1 attached as unit 4.

1.Backdoor functions

Enter your choice:
Set Transition mode ...Assigned Unit ID:[3]

Finish Set Transition mode ...
Enter Transition mode ...
Finish Transition mode ...
Enter Master mode ...
ISC: Stack status: Normal

Load certificate files : Starting
Load certificate files : Finished

Finish Master mode ...


Performing startup provision ...

................................................................................
..............................................................................--
-- master state preemption
................................................................................
................................................................................
................................................................................
................................................................................
.

Notify provision complete


Provision Complete ...
Finish Provision Complete ...

RE: 3com 3870 (3CR17451-9) Console Connection

I suppose just because you can see output doesn't mean your keystrokes are going in.

Instead of making a cable, why don't you just use a standard blue Cisco one?

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