Forum Discussion
NimbostratusMerging two different LTMs in a HA Pair - Q's
I have two F5 LTMs with different hardware: 1600 and 3600.
Both have the same software: BIG-IP 9.4.8 Build 355.0 Final
The configuration is just slightly different:
3600 is a production device and have different external interface with different external Self IP and VLAN.
The rest of the configuration apart from that single interface is exactly the same.
I would like to make a HA Pair adding the 1600 to production 3600.
Unfortunatelly I have no failover cable so I will have to do it network-based way.
And now the questions :)
1. can I build the HA Pair with different hardware nodes (1600 and 3600 in particular)?
2. what parts of config should definitely be common on both boxes, and which can't?
- as I wrote before, currently the configs are slightly the same apart from one interface
- of course I know I should change currentl IPs for floating and assign new IPs for both internal and external interfaces on both devices
3. what is the best way to do network based FO?
- dedicated port and vlan with unique addressing like 1.1.1.1 - .2 ?
Thanks in advance for your responses
6 Replies
- nitass
Employee
1. can I build the HA Pair with different hardware nodes (1600 and 3600 in particular)?it is not supported officially but technically, i think it is possible.
sol8665: BIG-IP redundant pair hardware and software parity requirements
https://support.f5.com/kb/en-us/solutions/public/8000/600/sol8665.html
2. what parts of config should definitely be common on both boxes, and which can't?configuration under local traffic menu is shared between unit in HA pair.
sol7024: Overview of the ConfigSync process (BIG-IP system files)
http://support.f5.com/kb/en-us/solutions/public/7000/000/sol7024.html
3. what is the best way to do network based FO?dedicated interface and vlan is the best practice.
sol11736: Defining network resources for BIG-IP high availability features (9.x - 10.x) (Network Failover)
http://support.f5.com/kb/en-us/solutions/public/11000/700/sol11736.html
hope this helps. 
emr_27148@nitass, many thanks...
ad 1
that's what I was looking for
ad. 3
it is clear for me
ad. 2
I know that it is ashared during the Config Sync process, but I wonder if there can be some problems while adding the second device to the pair, that already have some config fragments identical to the first device (for example hostname, or probabbly many others)
Any ideas??
I have one more question that came to my mind a while ago...
What will happen if both devices have the same license... I mean physically exactly the SAME one.
There reason for such strange situation is that i was given a temporary box (3600) and was supposed to build a temporary replica of production one (1600). then I had to switch them so that 3600 become productive and 1600 was decomissioned.
The borrowed temp 3600 had no license so I had to use the one from 1600.
Right now I was told that the 3600 was bought, and it is no longer temporary :)
I am supposed to make the HA pair of this two boxes now.
Hope that it clearly enough describes the situation.- nitassI wonder if there can be some problems while adding the second device to the pair, that already have some config fragments identical to the first device (for example hostname, or probabbly many others)
Any ideas?? i think you have to change hostname and unit id of 1600 unit.
What will happen if both devices have the same license... I mean physically exactly the SAME one. you cannot just move license (base registration key) from 1600 to borrowed 3600 unit. the license is tied to unit serial number. you should contact F5 guys to get temporary license for the 3600 unit. 
jokraglyDid you have any luck joining the 1600 and 3600 HA pair?
We are looking to do exactly this and don't really see the issue that F5 suggests as the 1600 will be decommisioned as soon as the config sync is done.
Just looking for you feedback on what you ended up doing.
ddqq_131111I have come across this thread via Google - it seems to be the only one covering off this topic!
I am wondering whether anyone who has tried this has had any success. I am looking at migrating a standalone 1600 to a pair of 4000s, and hope as part of this process to connect one or both of the 4000s into a failover group with the 1600 to minimise downtime.
Either way I'll report back on my findings once I do it, for anyone else who finds this article in future.
- Michael_Yates
Yes. I've done this twice in the past and am currently involved in a project that is collapsing 3 pairs of 6400's onto a pair of 8950S's.
I did it with Merge Files. I put out a Tech Tip on how to use them a few years ago for Bigpipe. If you are running on v11, then you can still do it...I just haven't written up anything on the How-To's.
This is for v9 and v10. https://devcentral.f5.com/articles/big-ip-and-merge-file-configuration-changes.UmCfcPnksmM
If you want to try it on v11 look into these commands:
tmsh load /sys config merge and tmsh load /sys config merge verify
The just of it is to take out all of the Subnet Ownership, VLAN's, Floating IP's, etc. and pack them into one or more Merge Files. Then shutdown the old device and merge in the VLAN's, Subnet's, Floating-IP's etc. in the right order following by your Monitors, Pools, iRules, and Virtual Servers.
NOTE: If you are thinking about trying to use this ability then I cannot stress enough that you practice it enough times to become good at it. I have actually met people that attempted to use it and didn't really know how....and had disastrous results.
Use it right and you will love it.
Hope this helps.
