RE: IBM i Access for Web vs IBM Navigator for i

More than just CPU cycles: I'm not sure of all the mechanics, but there's a timeout wait for an IPV6 DNS server to respond before it'll kick down to IPV4. That timeout is repeated, and repeated, and repeated on every access to a server, even if the IP address is given in IPV4 notation.

Java always "prefers" IPV6 unless you tell it otherwise on the java command line. The product I develop for RJS is a java web-app that talks to a java web-service, both running on i. Our customers started installing 7.1 (where the default for starting IPV6 changed) and performance on our product fell through the floor for some customers even though they had moved to a faster machine. The solution turned out to be either to turn off IPV6, or to add the -preferIPV4=true flag on the java command line, or to configure IPV6 properly.

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-
bounces@xxxxxxxxxxxx] On Behalf Of Jim Oberholtzer
Sent: Monday, November 04, 2013 7:21 AM
To: Midrange Systems Technical Discussion
Subject: Re: IBM i Access for Web vs IBM Navigator for i

Nevertheless, it's a reasonable question. If there is an attempt to
communicate with IPV6, then significant CPU cycles may be expended to
detect and communicate with the network. It's best to turn off IPV6
unless it is properly configured and in use. Remember the defaults are
on, not off.

Jim Oberholtzer
Chief Technical Architect
Agile Technology Architects


On 11/3/2013 5:45 PM, Jack Callahan wrote:

Do all these systems have IPV6 configured properly? This sounds a lot like

that problem. You don't notice it when all the IP you're doing is telnet or
FTP, but when you start to use highly interactive web interfaces, like
WebNav, missing IPV6 DNS server definitions KILL performance.

A bit presumptive of IBM to assume IPv6 is in use, if that's the cause of
the performance problem.

Haven't run across anywhere in IBM documentation the states IPv6 is the
preferred networking protocol for Navigator for i.

IPv6 certainly isn't in use on my firm's networks- still running IPv4
everywhere. And yet other web apps seem to run acceptably.
--

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