IPV6 and Java restart

[Former Member]

Hi,

We had an issue on Java start in our XI system and the issue got resolved after changing the following parameter

as per SAP recommendations:

-Djava.net.preferIPv4Stack=true

SAP says that Java is using IPv6 and hence the XI system Java is hanging and not able to comeup.

Can any body explain what this parameter and why Java suddenly using IPV6 instead of IPV4. We never changed

anything related to the above parameter before this incident.

Thanks & Regards,

DVRK

[blanca_serrano · Accepted solution]

Hello DVRK,

The reason for this is that the JDK uses the IPv6 protocol by default however the SAP application server components use IPV4, so it is necessary to set:

-Djava.net.preferIPv4Stack=true

This parameter forces the JVM to use the TCP IPv4 rather than IPv6 which is not compatible with our application server components.

I hope this explanation clarifies your doubts.

Also you can check note 1137949 regarding this.

Regards,

Blanca

[Former Member · Accepted solution]

Hi,

Thanks for your information.

But interestingly in our case, Java was running fine and when we restarted the server this issue came.

The parameter has never been set even in Dev and Quality systems. But the Java is running fine.

How come some suddenly the issue of IPV6 came after restart in production systems.

Were these settings of IPV were there at OS level also?

Thanks & Regards,

Venkata Ramakrishna

[thunder_feng · Accepted solution]

Hi Rama,

There must be some change on your system before the issue started to occur.

Please check this from your side once more, carefully.

Then could you please just remove the parameter from this system, and reproduce the issue, then share with us the detailed error logs, and also please share with us the same logs from your QAS/DEV system where it is working fine.

Hence probably we can do a comparation to get more hints.

Thanks

Thunder

[Former Member · Accepted solution]

Hi,

Thanks for the information.

Well, i cant change it and try on Production system. But I am sure that Dev and Quality systems are running without this

parameter and even production system is running fine even without this parameter before.

Our OS team is confident that they haven't made any changes. ( Does anybody advise me how to check this setting at OS level)?

Also, some one is saying that it could be a bug in SAP.

We need some clarification from SAP at least in this regard.

Thanks & Regards,

Venkata Ramakrishna