HA/LoadBalance using OSA-Express to 6509's

[pmajumder]

Hi All,

I am trying to setup a HA/Loadbalance environment to our Mainframe using OSPF via 2 OSA-Express cards (Each card has 2 ports for a total of 4). 2 ports connect to 6509-A, and the other 2 to 6509-B.

OSPF area 1 between the 6509's and the mainframe is defined as a TSA. All the ip addresses assigned to the OSA's are on the same VLAN/Subnet. The VIPA address on the mainframe is on a separate subnet.

The problem that we are running into is that only one OSA port (say OSA-0) is sending hello packets, and thus we land up with only one neighbor/route. If we shut of OSA-0 then another OSA sends the hello and a new neighbor/route is formed.

Thus we have achieved the HA (failover) capability, but not the load distribution.

Can anyone please help me with this - any pointers, suggestion... Let me know if additional info is required - 6509 OSPF defs, Mainframe TCP/IP parms, OMPROUTE, etc.

Regards

Pradeep

[ehirsel]

Please post your mainframe system's OSPF config, your 6509 ospf config, and the mainframe tcpip parms, especially those that contain the vipa addresses.

Thanks.

[pmajumder]

I have attached the configurations as follows:

TEST.OMPCONFG.TXT = Mainframe Omproute

TEST.PROFILE.TXT = tcpip parms/home

Rtr-OSPF = OSPF from 6509's.

I have tried it with & without the parallel_OSPF=Backup/Primary staements in the omproute file.

Thanks for your help,

Pradeep

[ehirsel · Accepted solution]

I don't know what mainframe OS you are using, but I did a search on IBM's mainframe library and I came across this URL:

http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/F1A1B420/2.1.9?SHELF=E0Z2IN35&DT=20020604120755

Here is what it has to say with regards to the parallel_ospf parm:

Parallel_OSPF

This parameter designates whether the OSPF interface is primary or backup when more than one OSPF interface is defined to the same subnet. Only one of these interfaces can be configured as primary, meaning that it will be the interface to carry the OSPF protocol traffic between OMPROUTE and the subnet. Failure of the primary interface results in automatic switching of OSPF traffic to one of the backup interfaces. If the primary interface is later reactivated, OSPF traffic will not be automatically switched back from the backup interface to the primary interface. If you want to switch traffic back to the primary interface, the backup interface must be stopped. If none of the interfaces to the common subnet are configured as primary, a primary interface will be selected by OMPROUTE. Valid values are "Backup" and "Primary".

It looks like the behavior is by design. You have multiple OSPF interfaces on the same subnet.

If you want to use parallel links for load-balancing, then you can create different vlans on the 6509, and reconfig the OSA ports to be on seperate subnets. You can still use the VIPA, but now you can achieve the use of load-balance using OSPF.

Let me know if this helps. My search was done using the z.os v1r3 library. And the result that I found was from the CS v1r4.0 ip config reference.

[pmajumder]

Hi Edward,

That was very helpful - we are using zOS. However, I was hoping I did not have to create separate vlans/subnets to do the load distribution. I thought the Multipath statement in the m/f omproute file would take care it.

Thanks again for your help!

Regards

Pradeep