Attempting to create a UDR route using "-AddressPrefix VirtualNetwork" results in error

Question

Attempting to create a UDR route using "-AddressPrefix VirtualNetwork" results in error

GavinS 6

Hi Azure team,

There appears to be a bug / missing feature in "Virtual network service tags" for User-Defined Routes

According to the table on page https://learn.microsoft.com/en-us/azure/virtual-network/service-tags-overview#available-service-tags , "VirtualNetwork" is a valid service tag that should be usable in UDR static routes, however I receive the following error every time I try to use it.

Set-AzRouteTable: C:\Scripts\Powershell\Azure\DC\Azure_Build_xxx_v10.ps1:1314:19
Line |
1314 | $RouteTable | Set-AzRouteTable
| ~~~~~~~~~~~~~~~~
| Address prefix VirtualNetwork of resource
| /subscriptions/a9xxxxxxx/resourceGroups/RG_DC_002_westeurope/providers/Microsoft.Network/routeTables/UDR_NET_FW-HA-02/routes/VirtualNetwork is not formatted
| correctly. It should follow CIDR notation, for example 10.0.0.0/24. StatusCode: 400 ReasonPhrase: Bad Request ErrorCode: InvalidAddressPrefixFormat ErrorMessage: Address prefix
| VirtualNetwork of resource
| /subscriptions/a9xxxxxxx/resourceGroups/RG_DC_002_westeurope/providers/Microsoft.Network/routeTables/UDR_NET_FW-HA-02/routes/VirtualNetwork is not formatted
| correctly. It should follow CIDR notation, for example 10.0.0.0/24. OperationID : c0d8805f-94c1-4684-88f8-89be133b2ad9

The command causing the error is the following:
Add-AzRouteConfig -Name "VirtualNetwork" -AddressPrefix "VirtualNetwork" -NextHopType "None" -RouteTable $RouteTable

By comparison, if I use a different service tag, it works correctly, e.g.
Add-AzRouteConfig -Name "StorageRoute" -AddressPrefix "Storage" -NextHopType "None" -RouteTable $RouteTable

According to the URL at the top of the post:
"Note: As of March 2022, using service tags in place of explicit address prefixes in user defined routes is out of preview and generally available."

With that in mind, can you please advise:
A. why using the service tag "VirtualNetwork" (i.e. -AddressPrefix "VirtualNetwork") is not working?
B. when it will be implemented (in my case, specifically in westeurope and northeurope)

[ Note: using -AddressPrefix "VirtualNetwork" is exactly what I want to do in a number of UDRs, so it is an important issue to correct ]

Many thanks!

mohamed elnaggar 1 Reputation point

2022-04-25T12:36:15.25+00:00

Learn about how Azure routes traffic between Azure, on-premises, and Internet resources. Azure automatically creates a route table for each subnet within an Azure virtual network and adds system default routes to the table. To learn more about virtual networks and subnets, see Virtual network overview. You can override some of Azure's system routes with custom routes, and add additional custom routes to route tables. Azure routes outbound traffic from a subnet based on the routes in a subnet's route table.
GavinS 6 Reputation points

2022-04-25T13:21:42.72+00:00

Thanks for the reply, mohamedelnaggar-5194 - I am familiar with everything you say, but that's not what my problem description talks about.

The issue is that the URL says that there should be a specific service-tag named "VirtualNetwork" that can be used in "network security groups, Azure Firewall, and user-defined routes".
I'm trying to use that service-tag in a UDR, but it is not actually available in UDRs yet for some reason, despite what the URL says
ChaitanyaNaykodi-MSFT 27,476 Reputation points Microsoft Employee Moderator

2022-04-27T00:28:11.413+00:00

Hello @GavinS , Welcome to the Microsoft Q&A forum. Adding “VirtualNetwork” tag as address prefix is not supported. You have to add address prefix in CIDR format currently. I have reached out to the team internally regarding this issue and will let you know if this is something which can be implemented in the future. Thank you!
GavinS 6 Reputation points

2022-04-27T10:42:43.167+00:00

Hi ChaitanyaNaykodiMSFT-9638,

If you look at the table showing the available service tags at the URL, https://learn.microsoft.com/en-us/azure/virtual-network/service-tags-overview#available-service-tags, you can see that it says the "VirtualNetwork" is supported (see below screen snip), so the fact is not working must be a bug.

I note that you have reached out to the internal team. Can you let me know when they anticipate this bug will be fixed please?

Many thanks
ChaitanyaNaykodi-MSFT 27,476 Reputation points Microsoft Employee Moderator

2022-05-03T00:47:59.703+00:00

Hello @GavinS ,
Thank you for providing additional details and apologies for the delayed response here.

I got a response back from the team, adding support for “VirtualNetwork” tag as address prefix is currently in the roadmap but no ETA has been finalized on when this feature will be deployed.

I understand the documentation you shared above does not reflect this limitation. You can follow this documentation update request for this scenario.

Hope this helps! Please let me know if you have any additional questions. Thank you!
Jakob F. Norregaard 1 Reputation point

2022-06-23T07:29:09.05+00:00

Hi @GavinS , I received the same error yesterday (failing because expecting CIDR format) when trying to deploy an ARM template containing a route table using service tags (these were AzureMonitor and ApiManagement). I could fix it by updating the route table resource in the json to use the latest API version, see below (I was using 2017 version initially). Not sure if it helps but at least the issue is related.

Your answer

mohamed elnaggar 1 Reputation point

2022-04-25T12:36:15.25+00:00

Learn about how Azure routes traffic between Azure, on-premises, and Internet resources. Azure automatically creates a route table for each subnet within an Azure virtual network and adds system default routes to the table. To learn more about virtual networks and subnets, see Virtual network overview. You can override some of Azure's system routes with custom routes, and add additional custom routes to route tables. Azure routes outbound traffic from a subnet based on the routes in a subnet's route table.
GavinS 6 Reputation points

2022-04-25T13:21:42.72+00:00

Thanks for the reply, mohamedelnaggar-5194 - I am familiar with everything you say, but that's not what my problem description talks about.

The issue is that the URL says that there should be a specific service-tag named "VirtualNetwork" that can be used in "network security groups, Azure Firewall, and user-defined routes".
I'm trying to use that service-tag in a UDR, but it is not actually available in UDRs yet for some reason, despite what the URL says
ChaitanyaNaykodi-MSFT 27,476 Reputation points Microsoft Employee Moderator

2022-04-27T00:28:11.413+00:00

Hello @GavinS , Welcome to the Microsoft Q&A forum. Adding “VirtualNetwork” tag as address prefix is not supported. You have to add address prefix in CIDR format currently. I have reached out to the team internally regarding this issue and will let you know if this is something which can be implemented in the future. Thank you!
GavinS 6 Reputation points

2022-04-27T10:42:43.167+00:00

Hi ChaitanyaNaykodiMSFT-9638,

If you look at the table showing the available service tags at the URL, https://learn.microsoft.com/en-us/azure/virtual-network/service-tags-overview#available-service-tags, you can see that it says the "VirtualNetwork" is supported (see below screen snip), so the fact is not working must be a bug.

I note that you have reached out to the internal team. Can you let me know when they anticipate this bug will be fixed please?

Many thanks
ChaitanyaNaykodi-MSFT 27,476 Reputation points Microsoft Employee Moderator

2022-05-03T00:47:59.703+00:00

Hello @GavinS ,
Thank you for providing additional details and apologies for the delayed response here.

I got a response back from the team, adding support for “VirtualNetwork” tag as address prefix is currently in the roadmap but no ETA has been finalized on when this feature will be deployed.

I understand the documentation you shared above does not reflect this limitation. You can follow this documentation update request for this scenario.

Hope this helps! Please let me know if you have any additional questions. Thank you!
Jakob F. Norregaard 1 Reputation point

2022-06-23T07:29:09.05+00:00

Hi @GavinS , I received the same error yesterday (failing because expecting CIDR format) when trying to deploy an ARM template containing a route table using service tags (these were AzureMonitor and ApiManagement). I could fix it by updating the route table resource in the json to use the latest API version, see below (I was using 2017 version initially). Not sure if it helps but at least the issue is related.

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Attempting to create a UDR route using "-AddressPrefix VirtualNetwork" results in error

Your answer