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VLAN pool usage when having multiple VMM domains

suneq
Level 1
Level 1

Hi,

I would like to connect our VMware infrastructure to ACI. We have 10 DVS so we will configure 10 VMM domains for them.

My concern is: as each EPG should be "propagated" down to all 10 DVS, if I understand correctly, ACI will assign 10 different VLAN for each EPG and sooner or later, we will run out of VLAN in the VLAN pool.

I have 2 questions:

  • Was my understanding correct (ACI will assign 10 VLAN for each EPG in our scenario)?
  • If yes, do we have any solution to optimize the VLAN usage? Any kind of synchronization between VMM domains so that we can assign only 1 VLAN for each EPG for example

Thanks.

 

 

 

1 Accepted Solution

Accepted Solutions

Hi @suneq ,

From what I understand, they have 3 vCenters which manages 10 clusters; each cluster uses a seperate vDS and VLANs are propagated to all these 10 vDS.

Due to different reasons, they want to keep this architecture instead of reducing the number of vDS.


OK. You can build 10 VMMs in ACI and then add each of the 10 VMMs to each EPG to achieve what you want to do.

Normally, this would mean 10 VLAN Pools, each with its own range of VLANs.  However if you are concerned about running out of VLANs, I'd suggest the following: [Note: I have not tested the following and can't give you a 100% guarantee it will work]

  • Create one Dynamic VLAN Pool - but when adding the VLAN ranges, make each range Static
  • Use the same VLAN pools for each VMM (shudder - can't believe I just said that)
  • When mapping each EPG to each of the 10 VMMs, make sure you choose static mapping and choose the same VLAN each time

To be honest, I'd feel better advising:

  • Create 10 non-overlapping VLAN pools, one for each VMM with just enough VLANs to allow one per EPG
  • Just assign each EPG to all 10 VMMs - let ACI take care of the VLAN allocation
    • But this method will chew through your VLANs 10 times faster

 

RedNectar aka Chris Welsh.
Forum Tips: 1. Paste images inline - don't attach. 2. Always mark helpful and correct answers, it helps others find what they need.

View solution in original post

5 Replies 5

RedNectar
VIP
VIP

Hi @suneq ,

[Edit: Check another answer I just wrote too]


I would like to connect our VMware infrastructure to ACI. We have 10 DVS so we will configure 10 VMM domains for them.

That's about correct. But 10 vSwitches is quite a lot of vSwitches. But it's the next bit that worries me more

My concern is: as each EPG should be "propagated" down to all 10 DVS,

This is the bit that really confuses me - WHY would you have the SAME EPG on multiple vSwitches. To me, this just doesn't make sense.

if I understand correctly, ACI will assign 10 different VLAN for each EPG and sooner or later, we will run out of VLAN in the VLAN pool.

ACI really only needs one VLAN per EPG normally - but if you blindly go ahead and configure the same EPG on multiple VMM Domains, ACI will choose a VLAN from a VLAN Pool for that EPG - but you can control this using static mappings.

I have 2 questions:
  • Was my understanding correct (ACI will assign 10 VLAN for each EPG in our scenario)?
  • If yes, do we have any solution to optimize the VLAN usage? Any kind of synchronization between VMM domains so that we can assign only 1 VLAN for each EPG for example

The answer to both these Qs is "Not if you use static mappings."

If you want, you can map each EPG to the same VLAN that is using now - but you will have to create a Dynamic VLAN Pool, then add a static range of VLANs to this pool.

Remember every vSwitch needs an Uplink, so if you want two different vSwitches on the same ESI host, it will need two uplinks.  But this brings me back to my earlier comment. So this give me two questions:

  • If you don't need more than one vSwitch on any ESXi hosts, why do you have 10?
  • If you DO need more than one vSwitch on any ESXi hosts, why would the same EPG be on both?
RedNectar aka Chris Welsh.
Forum Tips: 1. Paste images inline - don't attach. 2. Always mark helpful and correct answers, it helps others find what they need.

Sergiu.Daniluk
VIP Alumni
VIP Alumni

I think first it's important to understand how your current vmware env is configured:

- how many vcenters you have?

- how many DVS per vcenter?

- how many DVS per host you have?

- how many datacenters you have in each vcenter?

 

If you could share a drawing with the design then we could make a better suggestion on how ACI VMM domain(s) should be configured.

Take care,

Sergiu

suneq
Level 1
Level 1

Hi,

My apologies for the late reply.

Thanks so much for your advices. I will have a meeting with the VM team soon and will ask them for more details.

From what I understand, they have 3 vCenters which manages 10 clusters; each cluster uses a seperate vDS and VLANs are

propagated to all these 10 vDS.

Due to different reasons, they want to keep this architecture instead of reducing the number of vDS.

Hi @suneq ,

From what I understand, they have 3 vCenters which manages 10 clusters; each cluster uses a seperate vDS and VLANs are propagated to all these 10 vDS.

Due to different reasons, they want to keep this architecture instead of reducing the number of vDS.


OK. You can build 10 VMMs in ACI and then add each of the 10 VMMs to each EPG to achieve what you want to do.

Normally, this would mean 10 VLAN Pools, each with its own range of VLANs.  However if you are concerned about running out of VLANs, I'd suggest the following: [Note: I have not tested the following and can't give you a 100% guarantee it will work]

  • Create one Dynamic VLAN Pool - but when adding the VLAN ranges, make each range Static
  • Use the same VLAN pools for each VMM (shudder - can't believe I just said that)
  • When mapping each EPG to each of the 10 VMMs, make sure you choose static mapping and choose the same VLAN each time

To be honest, I'd feel better advising:

  • Create 10 non-overlapping VLAN pools, one for each VMM with just enough VLANs to allow one per EPG
  • Just assign each EPG to all 10 VMMs - let ACI take care of the VLAN allocation
    • But this method will chew through your VLANs 10 times faster

 

RedNectar aka Chris Welsh.
Forum Tips: 1. Paste images inline - don't attach. 2. Always mark helpful and correct answers, it helps others find what they need.

suneq
Level 1
Level 1

Hi @RedNectar 

Thanks a lot for your answer, very clear as always.

I will try to test the solution you suggested with our lab and provide the feedback. 

Thanks again for all your help.

 

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