[Linux-cluster] RHEL3 Cluster Heart Beat Using Cross Over Cable

[Rick Stevens]

Nathan Nobbe wrote:
> On Thu, Nov 6, 2008 at 10:38 AM, Rick Stevens <ricks at nerd.com> wrote:
> 
>> lingu wrote:
>>
>>> Hi,
>>>
>>>  I am running two node active/passive  cluster running  RHEL3 update
>>> 8 64 bit  OS on Hp Box with external hp storage connected via scsi. My
>>> cluster was running fine for  last 3 years.But all of a sudden cluster
>>> service keep on shifting (atleast one time in a day )form one node to
>>> another.
>>>
>>>  After analysed the syslog i found that  due to some network
>>> fluctuation service was getting shifted.Both the nodes has two NIC
>>> bonded together and configured with  below ip.
>>>
>>> My network details:
>>>
>>> 192.168.1.2 --node 1 physical ip  with  class c subnet (bond0 )
>>> 192.168.1.3 --node 2 physical ip  with class c subnet (bond0 )
>>> 192.168.1.4  --- floating ip  ( cluster )
>>>
>>>  Since it is a very critical and busy server may be due to heavy
>>> network load  some hear beat signal is getting missed  resulting in
>>> shifting of service from one node to another.
>>>
>>> So i planned to connect crossover cable for heart beat messages, can
>>> any one guide me  or provide me the link that best explains  how to do
>>> the same and the changes i have to made in cluster configuration file
>>> after connecting the crossover cable.
>>>
>> The crossover cable is pretty easy to make and a lot of places have
>> ones prebuilt.  If you want to make one yourself, you're interested in
>> the orange pair of wires (normally pins 1 and 2) and the green pair of
>> wires (normally pins 3 and 6).  The blue and brown pairs don't do
>> anyting in standard TIA-56B cables.  The wiring diagram is:
>>
>>        End "A" (std)                   End "B" (crossover)
>>        pin 1           Orange/White    pin 3
>>        pin 2           Orange          pin 6
>>        pin 3           Green/White     pin 1
>>        pin 4           Blue            pin 4
>>        pin 5           Blue/White      pin 5
>>        pin 6           Green           pin 2
>>        pin 7           Brown/White     pin 7
>>        pin 8           Brown           pin 8
>>
>> Remember that the pins are numbered from the left, looking at the hole
>> the cable goes into with the latch on the bottom.  I generally put some
>> sort of rather blatant mark on any such cable such as a big piece of
>> tape or coloring the ends with a red marker so it's obvious that the
>> cable is "special".
>>
>> To use it, just plug one end of the cable into the cluster NIC of the
>> first system and the other end into the cluster NIC of the second
>> system.  You should get link lights at both ends.
> 
> 
> many modern machines will work w/o a crossover cable.   ive got 2 dell 1650s
> running heartbeat / drbd over a direct connection for heartbeat
> communication.  i dont need to use a crossover on the 1650s for the direct
> connection to work, and those boxes are pretty old by now.  so long story
> short, probly worth saving a little hassle and just trying a regular cat-5
> cable for the direct connection.
> 
> or if its a requirement for you hardware you can pick up a 3 foot crossover
> at radio shack, bust buy etc, for less than 10 bucks.

True.  Some NICs have autosense for MDI and MDIX cables (the technical
terms for straight and crossover, respectively), but a lot of them
don't.  Nathan's right, try a regular cable first.  If it doesn't work,
crossovers are available at lots of places quite cheaply.  They often
use red cable (the ones I've bought are red), but there are a lot of
straight cables that use red as well, so I'd still mark MDIX cables
very conspicuously.  A big tag that says "I'M A CROSSOVER" can't hurt!

My diagram above is valid if you really want to "roll your own".  I've
made so damned many CAT5/5e/6 cables in my life (MDI and MDIX both),
that I can do it almost in my sleep.  Ditto with thinnet (10Base-2) and
I'm a past master at putting parasite taps on thicknet (10Base-5)
cables, sticking on the transceivers and snaking that gawdawful AUI
cable down cable stud pockets.  I'm an original DECnet geek!
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- Rick Stevens, Systems Engineer                      ricks at nerd.com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
-                                                                    -
-      On a scale of 1 to 10 I'd say...  oh, somewhere in there.     -
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