Forum Discussion
CirrostratusF5 BIG-IP's in Different Datacenters
Hi everyone
if i implemented this setup:
What will happen if both ha links are down, each F5 device will think he is the active unit? if yes, how to mitigate this issue?
is there any solution like "witness" device to signals both devices and control the fail-over process?
Thank you
Mohanad
If all your links are down, then you go split brain. But if all your links are down, then you have more problems than just the split brain BigIP.
(Note that the way I usually do this is an HA pair in each DC (Or metropolitan DC pair). Then use GTM to provide global resilience).
Regarding fancy devices not requiring your network to be up to prevent split brain. Why bother? You can always put in a path that would encompass the same links as the failover clustering using witness. You're not limited to just two links.
MohanadAny luck??
NathWhat are you trying to achieve of having both F5 on both DC?
- Mohanad
Hi Nathaneil
two big-ips in different DC
HamishCirrocumulus
How to mitigate?
You have multiple links. The links should have no single point of failure. i.e. separate switches, separate links from separate providers and make sure you check the actual paths of each
H
- Mohanad
Hi Hamish,
What if the two links are down? im trying to find similar solution like this but at the big-ip level
https://docs.microsoft.com/en-us/windows-server/failover-clustering/deploy-cloud-witness
- Hamish
If all your links are down, then you go split brain. But if all your links are down, then you have more problems than just the split brain BigIP.
(Note that the way I usually do this is an HA pair in each DC (Or metropolitan DC pair). Then use GTM to provide global resilience).
Regarding fancy devices not requiring your network to be up to prevent split brain. Why bother? You can always put in a path that would encompass the same links as the failover clustering using witness. You're not limited to just two links.
- Azzeddine_S
Cirrus
Actually connecting two devices directly to each other is not supported by F5
The reason is pretty simple, if the link is down both devices will initate a failover process and you can end up with dual active scenario .
what F5 is recomanding is passing through switches on both sides, in this case phisical failure will be contained within the segment (switch to BIG-IP) and the high avalability monitoring still work because both devices are monotoring each other through TCP.
Passing through switches can also improve scalability, with direct connection you will be limited to only two BIG-IPs.
This is for a single data center, for more you should carefully take in consideration the F5 recommendations for high availability such as band width for synchronization and mirroring , latency etc...
good luck
- Mohanad
Hi Azzeddine
thanks for your reply, this is just a diagram to describe the issue, we are using switches between all network devices.
im trying to achieve this:
The link you have shared talks about ASM sync... https://devcentral.f5.com/s/articles/syncing-asm-waf-policies-between-f5-big-ips-in-different-datacenters-or-cloud-regions-32891
f5 recommends; 1) Dedicated VLAN for HA failover; in failover IP address list, you have the self IP
2) Add Management IP in the failover IP address list
Review K16049 for more information on how to limit failover disruptions.
With Load aware (or HA Order) configurations, if both links, HA and management are down, you will see A-A situation.
However, you could test HA Group.
- Mohanad
Thank Gr3asy so much, i will read K16049
