Does servicegurad support crossover cables on HP 11.23?

[P Turner]

I have been told that the latest version of MC/ServiceGuard that comes with the HP-UX 11.23 Mission Critical Operating Environment doesn't support crossover cable. Can this be confirmed?

Regards

Tariq

P.S. this thread has been moved from HP-UX > System Administration to HP-UX > Seviceguard - HP Forums Moderator

[Geoff Wild]

As far as I know, HP has never "officially" supported the use of cross over cables between nodes in a cluster - on any version.

In
http://docs.hp.com/en/B3936-90095/B3936-90095.pdf
there is no mention of cross over cables....

Rgds...Geoff

[RAC_1]

Yes. It is not supported. The realse notes and manual for 11.16 says so.

[melvyn burnard]

Well this has been asked before, and as before I will post the following:
Pros and Cons of using a Crossover cable with ServiceGuard


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We often get questions asking whether Crossover cables are supported for use in a ServiceGuard cluster. The short answer is YES, but there are some important issues that you should be aware of:

This solution only works in a two node cluster. There is no way to have a Standby LAN card when using a Crossover LAN cable, so it is not possible to use SG local LAN failover.

When either LAN card fails, or the crossover cable is disconnected, both LAN cards go down. This is because the electrical signals necessary for the cards to determine that a valid LAN connection exists are not present. The result is that since both nodes appear to have a bad LAN card, ServiceGuard may TOC the wrong node. If a hub was used between the two LAN cards, then the hub would provide the electrical signals to the other card, allowing it to stay up.

On multi-speed cards, such as 10/100Base-T, the cards must negotiate which speed will be used when the system boots up. If only one system is booted and the remote system is down, then the negotiation will fail, and the card will not be enabled at all. So when the second node eventually comes up, it's LAN will also be down. If a hub is used, then the negotiation will succeed, so the LAN cards will come up at bootup, even if only one node is running.
It may be possible to force some multi-speed LAN cards to bypass the negotiation at bootup and to use a predetermined fixed speed. If this is possible, then would allow the two systems to boot up at different times and still use the Crossover cable connected LAN cards once they are both booted up.

Since both cards may go down when there is a failure when a Crossover cable is used, it can be difficult to determine where the problem lies. Another problem using Crossover cables is that if they are not properly labeled, they may accidently be used in situations where they will not work.
For the reasons listed above, HP does not recommend using Crossover cables for ServiceGuard configurations. However, they are still supported as long as you are willing to accept the above limitations. Using a Crossover cables is cheaper than using a hub, but it compromises the HA solution.
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To my knowledge we have not changed this statement

[A. Clay Stephenson]

Supported or unsupported, using a xover cable is less than wise. You are trading what you consider to be a SPOF (the additional hub) for a lack of diagnostics. It's very nice to know which end of your heartbeat is not working. That's what those winky-blinky lights on the hub buys you. As for eliminating a SPOF, you're really not because you need at least 2 heartbeat LAN's anyway.

[Nguyen Anh Tien]

MC/SG 11.16 support for crossover cables.
I have not used the latest version so that i can not confirm with U

[Mohanasundaram_1]

Hi Melvyn,

I have seen this statement quite a few times and have quoted the same to some customers. But is this statement made available in a formal document?

I do not find a mention of cross-over cable heartbeat in "managing serviceguard" manuals. But there is a mention of Serial heartbeat in that manual.

When I quote this statement most of the times customer ask for a formal HP document.

With regards,
Mohan.