Is it possible to add more than 300 rules for load balancer?

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Is it possible to add more than 300 rules for load balancer?

vsi_pranav 161

Hello,
I have Standard Public Load Balancer in place and VM Scale Set placed behind the load balancer. I am running the WebRTC application on VMSS which usually requires UDP port range (For eg Port 10000 to 110000) open for communication. I opened the ports in the VMSS Network Security Group. Now in order to get this application to work, is seems that I need to configure the load balancing rules for each and every port but the load balancer is not allowing me to have more than 300 rules per NIC. I already have 8 rules in place so starting from the port range 10000 for both front end and back end, I was able to add rules for port up to 10292. But After that I am getting following error. ErrorCode: LoadBalancerRuleCountLimitReachedForNic

As all VMs in VMSS share the same NIC, I am not able to add more than 300 rules, but I need to have more rules for it to work. I am literally stuck at this issue and have no clue how to proceed forward. Kindly please suggest some work around or solution for this.

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Answer 1

GitaraniSharma-MSFT 50,096 Microsoft Employee Moderator

Hello @vsi_pranav ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

The limit of rules per NIC (across all IPs on a NIC) for a load balancer is 300 and it is a hard coded limitation that cannot be increased.
Please refer : https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/azure-subscription-service-limits#load-balancer

The only workaround is to add another pool for a new VMSS, and create rules for the new pool.

Kindly let us know if the above helps or you need further assistance on this issue.

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vsi_pranav 161 Reputation points

2021-05-11T12:02:27.203+00:00

Thank you for the reply.
I will try this solution and will update here accordingly.

Also, I had one doubt. If I use Application Gateway instead of Standard Load balancer, will that make any difference?
Or is there any provision for mentioning port range in the rule?
GitaraniSharma-MSFT 50,096 Reputation points Microsoft Employee Moderator

2021-05-11T12:25:21.177+00:00

Hello @vsi_pranav ,

Azure Load Balancer is a high-performance, ultra low-latency Layer 4 load-balancing service (inbound and outbound) for all UDP and TCP protocols.
Application Gateway provides application delivery controller (ADC) as a service, offering various Layer 7 load-balancing capabilities and is used for HTTP/s applications. And application gateway limits 100 active listeners with 100 HTTP load balancing rules.
Refer : https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/azure-subscription-service-limits#application-gateway-limits
There is no provision to mention port range in the rule.
So I believe load balancer is the right option for you.

Thanks,
Gita
vsi_pranav 161 Reputation points

2021-05-12T03:52:42.55+00:00

Hello, I tried adding another VM scale set to the existing load balancer.
While creating the scale set we get the option to add it to load balancer under the Networking section. I checked the option and selected the existing load balancer in it. Also with this I had to select the same virtual network which load balancer is using otherwise it is not allowing me to select the existing load balancer. If I try to create the new virtual network, I am getting the error that load balancer is in another virtual network. I think due to this, new NIC is not getting created as it is using the same vnet and nic. In result I still am not able to add more rules to my load balancer.

Is there any solution for this? Kindly please help.
GitaraniSharma-MSFT 50,096 Reputation points Microsoft Employee Moderator

2021-05-13T14:04:58.097+00:00

Hello @vsi_pranav ,

Did you try to create a new NIC and select it as below:
GitaraniSharma-MSFT 50,096 Reputation points Microsoft Employee Moderator

2021-05-25T13:20:39.083+00:00

Hello @vsi_pranav , do you have any updates on this issue?
vsi_pranav 161 Reputation points

2021-05-26T15:53:54.7+00:00

Hello @GitaraniSharma-MSFT Tried the above said solution but it did not work. It is not allowing me to select the existing vnet. The only workaround I found on it was to create the another backend pool and add the new virtual machine scale set to the newly created backend pool. Then only I am able to create another set of 300 rules.
GitaraniSharma-MSFT 50,096 Reputation points Microsoft Employee Moderator

2021-06-01T14:19:16.653+00:00

Hello @vsi_pranav ,

As I already mentioned in my first answer that the only workaround is to add another pool for a new VMSS, and create rules for the new pool. So that is the only way to get around this hard coded limitation.

Kindly let us know if you need further assistance on this issue.

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Is it possible to add more than 300 rules for load balancer?

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