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Status Not under consideration
Workspace IBM i
Categories Networking
Created by Guest
Created on Mar 9, 2021

Transfer IP addresses seamlessly in IBM i from one Ethernet Line description to another line description without interruption

It is currently not possible in IBM i to transfer an IP address from one Ethernet line description to another without interruption. The IP address must be stopped, deleted and recreated with the reference to the new Ethernet line description. If the default gateway is affected, it must also be deleted and recreated. Downtime cannot be avoided in the IBM i OS. In AIX, however, this is possible without downtime. The AIX command is for example: "ifconfig en0 10.111.10.20 transfer en1".
https://www.ibm.com/support/knowledgecenter/ssw_aix_72/i_commands/ifconfig.html

This functionality should also be available in IBM i.


Use Case:

The customer operates his business critical IBM Power 980 24x7 with IBM i and AIX LPARs. The network interfaces should be switched from VIOS-SEA to vNIC without interruption during ongoing operation. The active IP address can be transferred seamlessly to the new vNIC Ethernet line descprition. No business critical downtime is needed.


Idea priority High
  • Guest
    Jun 25, 2021

    IBM does not intend to provide a solution to this request. An existing solution is available and additional information was not provided to indicate how it does not satisfy the request. Using virtual IP addresses with proxy ARP controlled through the preferred interface list allows a user to accomplish a switch between two physical lines without changes to existing support.

  • Guest
    Jun 15, 2021

    The CAAC has reviewed this requirement and recommends that IBM not implement this request. There are alternate ways to set up your configuration -- set up 2 physical cards to a single IP group instead to get a seamless continuous connection even if one card fails.

    Background: The COMMON Americas Advisory Council (CAAC) members have a broad range of experience in working with small and medium-sized IBM i customers. CAAC has a key role in working with IBM i development to help assess the value and impact of individual RFEs on the broader IBM i community, and has therefore reviewed your RFE.

    For more information about CAAC, see www.common.org/caac

    Nancy Uthke-Schmucki - CAAC Program Manager

  • Guest
    May 25, 2021

    Using VIPA is a tested and supported method of moving an IP address on IBM i. Transferring an IP address from one line to another and a VIPA with proxy ARP moving from one line to another would need to send the same ARP packets. Both should send out gratuitous ARPs announcing the new MAC address.

    For a VIPA, we send a single gratuitous ARP immediately after the move and then repeat twice more at 30 second intervals. If another device on the network processes that gratuitous ARP, there would be no confusion. If they don't, that device would need to send ARP to query the address to determine the new MAC address.

    Please provide additional details on if the use of VIPA satisfies your request and if not, the details on how it does not meet your needs.

  • Guest
    May 10, 2021

    The VIPA configuration can be of help, but also can have impact on network infrastructure like VPN routers etc which might get confused by the ARP packets created by this configuration. It is not recommended to simply try this solution in a production environment as it can create broadcast storm or other issues.
    It would be preferable to have a tested method (with or without MAC address transfer between the interfaces).

  • Guest
    Mar 24, 2021

    We believe that there is an existing solution. Using virtual IP addresses with proxy ARP controlled through the preferred interface list would allow you to accomplish a switch between two physical lines without changes to existing support. The preferred interface list can be changed while the interface is active, and could move the proxy of a VIPA from one line to another. Routes can't be bound to VIPA interfaces, but duplicate routes bound to separate interfaces on each adapter could be used. Route priority controls which route is used and this can be changed on active routes.
    For more information on configuring a virtual IP address associated with multiple interfaces, see Failover using automatic interface selection (https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_74/rzajw/rzajwconfiglb.htm).
    For more information on setting a preferred interface list, see Failover using a preferred interface list (https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_74/rzajw/rzajwcpil.htm).

    Does this existing solution satisfy your request? If not, please expand on how this solution does not meet your needs.