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  3. October 2013

Re: Setting IP redunduncay in AS/400

Yes thanks for reminding us, this is available and it does work!

Considerations and thinking for this option to assign the LCLIFC:

1) ONLY ONE can be assigned to each physical interface IP.
2) The interface must be shut down to change this interface.

Note that you can assign multiple physical interfaces to each Ethernet line. Then you could assign a different virtual IP as the LCLIFC to each of the IPs on the line. Cool. But this creates another ambiguity as there are now multiple IPs again!

This is also where I point out that some applications can be bound to a single IP address. You may want to look into this for the application so that you remove the ambiguity with this.

Finally one other thing that can bite you in the butt with redundancy is that some vendors (banks come to mind) restrict access by MAC address. This means you'll need to assure that if you fail over to another Ethernet line that the MAC address of that line is also allowed through the firewall!


- Larry "DrFranken" Bolhuis

www.frankeni.com
www.iDevCloud.com
www.iInTheCloud.com

On 10/1/2013 2:57 PM, Evan Harris wrote:

In addition to what the Dr has said, when using Proxy ARP for IP Redundancy
I found it useful to specofy the Associated local interface (LCLIFC)
parameter on the IP Interface definition (ADDIPIFC). This helped a good
deal with the firewall issues.

The Proxy ARP box visible in Ops Navigator must be ticked - you have to do
this from Ops Nav (or at least used to) there is/was not green screen
interface equivalent.




On Wed, Oct 2, 2013 at 4:04 AM, Midrange <midrange@xxxxxxxxxxxx> wrote:

Requirements:
1) at least on additional Ethernet port, preferable NOT on thee same
card as the current production interface also preferably to a different
physical switch.
2) TWO additional IP addresses in the same subnet as the production
interface.

Steps:
A) create a new IP interface using one of the new IP addresses and
attach it to the current Ethernet line description, and start the interface.
B) create a new line description for the new port you are adding and
vary it on.
C) create a new IP interface using the other of the new IP addresses and
attach it to the new line description, and start this interface.
D) using DSPLIND display each of the two lines and record the smallest
of the two frame sizes.
E) now in IBM i Navigator create a connection to the server using one of
the two new interfaces, NOT the current production interface. (It will
become apparent in a moment why this is important. )
F) locate networking, TCP/IP and IPv4. Expand that to see the IP
interfaces. You should see the three for this effort plus 127.0.0.1 and any
used for tools like iTerra, Maxava, Mimix, PowerHA etc.
G) Right click on the production IP address and end it. DID I MENTION
THIS WOULD BE DISRUPTIVE? Yeah could be! This is also why you don't want to
be connected to this IP address at this time. :-)
H) Now delete the production IP from the server.
I) Now create a new IP Interface that is type VIrtual. Attributes
required:
- Use the Production IP address
- Subnet mask of 255.255.255.255 Seems just wrong but it is correct.
- On the advanced tab check the Proxy Arp box.
- On the advanced tab enter the frame size recorded in D above.
- IF you prefer that traffic flow over one of the two lines, select
that as the preferred interface. Otherwise leave this alone. You might do
this if one of the lines is 1G and the other is 100M, prefer the 1G line in
this case.
J) Now start the interface and you're back in business.

Considerations:
I) You can now pull either line out or fail a card or switch port or cut
a cable and the users will not know.
II) Traffic will be flowing almost exclusively over just one of the
lines. If that's the one that fails then traffic moves to the other line
immediately. The system will issue a gratuitous ARP to inform everyone on
that subnet that the MAC address of the interface has changed.
III) IMPORTANT: Traffic that is INITIATED from the server (e.g. EDI or
bank transmissions) will come from one of the two new interfaces now,
NEVER from the production IP. This has firewall implications, understand
this.
IV) For enhanced reliability set the CMNRCYLMT parm on the Ethernet
line descriptions to (1 0) for infinite retries. You can do this while the
lines are varied on.
V) This works on V5R3 and up.

Done from memory while off line, please forgive any slight discrepancies
in terminology to what's on the screen.

DrFranken
Sent from my iPad

On Oct 1, 2013, at 10:07 AM, Vikhyath Kamath <vikyat_kaamath@xxxxxxxxx>
wrote:

*This message was transferred with a trial version of CommuniGate(r) Pro*
Hi,

We use IBM i V6R1.

We have a 2 or more LAN adaptors in each LPAR. We use one IP for HA
(ITERA) and other is accessed by users.

Thanks and Regards,
Vik.


________________________________
From: Midrange <midrange@xxxxxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Sent: Tuesday, October 1, 2013 7:04 PM
Subject: Re: Setting IP redunduncay in AS/400


Please tell us the software release as the available options change
significantly. If you are truly running AS/400 then you may not have
options. Also do you have more than 1 LAN card available for each
partition?

DrFranken.

Sent from my iPad

On Oct 1, 2013, at 9:22 AM, Vikhyath Kamath <vikyat_kaamath@xxxxxxxxx>
wrote:

Hi,

We have 5 LPARs on each of our servers. Recently we faced an issue
where the LAN adaptor of iseries system failed and we had a five hour
outage.
I was considering if we could have IP redundency - so that each LPAR
would have 2 IPs pointing one IP which the user access. So if one IP fails,
there is a fail-over to the other IP. Could some please guide how this is
done in AS/400 system?

Thanks and Regards,
Vik.
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