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HA score - does not Failover to Device With Best HA Score

Luis_Ribeiro
Nimbostratus
Nimbostratus

Hi,

I'm doing test to confirm the HA behavior.

I have a BIG-IP cluster of two i5800 devices, version 14.2.6. Each device has one trunk with two interfaces (for service, others for HA and SYNC).

 

What I want to do is:

- if one interface goes down, on first device - F5.A,

- then should fail-over to the other device - F5.B (with all interfaces up).

- if the second device F5.B have two interfaces down

- then should fail-over to first device F5.A.

 

But what I get is something I cannot understand, from the parameters of HA group. The traffic group is configured to be "Failover to Device With Best HA Score".

 

The tests I did:

 

| Device | Active Bonus | weight | minimum members | Score Contribution | Status    || Int.1  | Int.2  |

Test1:

| F5.A   | 15                 | 15      | 2                            | 0                            | Stand By || Down | Up     |

| F5.B   | 10                 | 10      | 2                            | 0                            | Active     || Down | Down |(*1)

 

Test 2: Change the "minimum members" parameter

| F5.A   | 15                 | 15      | 1                            | 8                            | Active     || Down | Up    |(*2)

| F5.B   | 10                 | 10      | 1                            | 0                            | Stand By || Down | Down |

 

Test 3: Bring UP all the interface on F5.B

| F5.A   | 15                 | 15      | 1                            | 8                            | Active     || Down | Up  |(*3)

| F5.B   | 10                 | 10      | 1                            | 10                          | Stand By || Up     | Up  |

 

Notes:

(*1) Why the device F5.B is active with all interfaces down and F5.A with up interface is in StandBy?

(*2) It´s ok

(*3) Why the device F5.A still ACTIVE with worst HA score? Why do not fail-over to F5.B?

I cannot understand what is the role of the "Active Bonus".

The interface are shutdown at LAN switch, connected to host A (where is F5.A) and host B (where is F5.B).

 

What parameters should I use to get the right behavior?

 

The configuration for the vCMP regardig HA group, for the final test 3:

# vCMP F5.A:

sys ha-group HA_GROUP_C1 {

   trunks {

       Service_InOut {

           minimum-threshold 1

           percent-up 50

           weight 15

       }

   }

}

 

# vCMP F5.B:

sys ha-group HA_GROUP_C1 {

   trunks {

       Service_InOut {

           minimum-threshold 1

           percent-up 100

           weight 10

       }

   }

}

 

-----

The trunk name Service_InOut

#----------------

# F5.A:

net trunk Service_InOut {

   cfg-mbr-count 2

   id 32767

   interfaces {

       2.1

       2.2

   }

   mac-address 00:94:a1:9b:c5:23

   stp disabled

   type ha-only

   working-mbr-count 1

}

 

#----------------

# F5.B:

net trunk Service_InOut {

   cfg-mbr-count 2

   id 32764

   interfaces {

       2.1

       2.2

   }

   mac-address 00:94:a1:9b:d4:23

   stp disabled

   type ha-only

   working-mbr-count 2

}

 

I appreciate your help.

Thanks

Luis

 

 

3 REPLIES 3

The active bonus add's weight to the active device.

(*1) Why the device F5.B is active with all interfaces down and F5.A with up interface is in StandBy?

In *1 the minimum members is 2, both HA groups do not have 2 active members, the active will stay active. (

(*2) It´s ok

(*3) Why the device F5.A still ACTIVE with worst HA score? Why do not fail-over to F5.B?

In *3 the active bonus counts for the A device, so it will stay active.

 

Cheers,

 

Kees

Luis_Ribeiro
Nimbostratus
Nimbostratus

Hi Kees.

 

To avoid the case (*3) it's better to have the active bonus set to zero, or close (less than the half of HA weight).

The active bonus solve also case (*1).

 

I did more 3 tests and the active bonus set to zero works fine. The ACTIVE/StandBy follow the HA score and the number of up interfaces. So for this scenario the active bonus is not good.

Are there any inconvenient to have zero for active bonus?

 

The tests:

Start with F5.A ACTIVE (all interfaces UP), and F5.B StandBy (all interfaces UP)

 

| Device | Active Bonus | weight | minimum members | Score Contribution | Status  || Int.1 | Int.2 |

Test4:

| F5.A  | 0           | 15   | 1              | 8                 | Stand By || Down | Up   |

| F5.B  | 0           | 10   | 1              | 10                | Active  || Up   | UP   |

Test5:

| F5.A  | 0           | 15   | 1              | 8                 | Active  || Down | Up   |

| F5.B  | 0           | 10   | 1              | 5                 | Stand By || Down | UP   |

Test6:

| F5.A  | 0           | 15   | 1              | 0                 | Stand By || Down | Down |

| F5.B  | 0           | 10   | 1              | 5                 | Active  || Down | UP   |

 

With these parameters I do not get the issue (*1), a device to be ACTIVE with no up interface to give service!

 

Thanks Kees.

 

Best Regards,

Luis.

You're welcome Luis. And glad it is now clear.