null modem cable work as heart beat??

[Salm]

I have 2 D class servers, each have only one network card, so I can not configure any network card for only hear beat.I want to connect serial port thought cable for heart beat. My question is > Null modem 9 pin cable will work as hear beat ?? or I have to buy an other staight cable ??

[A. Clay Stephenson]

Since you are talking port to like port (DCE to DCE), a straight cable couldn't possibly work.

[Stephen Doud]

A serial connection is not a heartbeat connection... but a pseudo-heartbeat connection which is only used after the primary heartbeat LAN has failed to transmit.
The serial HB line is used by Serviceguard to sustain cluster life just long enough to determine which node's HB NIC has failed. At that point, the node being determined to have failed is TOCd.

I don't have any details on the D-class, an obsolete server, but I have this:

In an RS-232 connection, use a null modem cable for DTC-to-DTC and a straight through cable for DTC-to-DTE:

DTC-to_DTC
2 -------- 3*
3 -------- 2*
7 -------- 7


DTC-to-DTE
2 -------- 2
3 -------- 3
7 -------- 7

[Salm]

Thanks for reply

Actually I'm using these servers only for practicing labs. I have only 1 lan card in each server.
Clay : you mean should I Buy one more lan card for heartbeat purpose???

Stephen: can you explain more about DTC to DTC and DTC to DTE.?? you mean both cable ( straight and null would work ??)

[A. Clay Stephenson · Accepted solution]

Data Terminal Equipment and Data Communications Equipment are two flavors of RS232 devices. The idea was that a DTE to DCE connection could use a straight connection because, for example, pin2 would be an output on one end and an input on the other.
http://en.wikipedia.org/wiki/DTE

Whenever you connect like-to-like (DCE-DCE or DTE-DTE), then you must cross connect the various inputs and outputs.

If I take you at your word, when you say that each D-box has only 1 network card then that means that you already have 2 network connections. The "card" and the built-in 10-Base-T port. In a similar manner to a serial heartbeat cable, if you are going to connect
the 10-Base-T ports together directly, you also need a crossover cable although straight cables with a cheap hub in the middle is better.