Multi-Subnet AlwaysOn: Is Routing and Remote Access always required?












1















Context



I'm setting up a 2-node AlwaysOn Availability Group (SQL Server 2017 Enterprise) with the following setup:




  • Existing DC+DNS (One NIC: 10.20.11.1/255.255.254.0)

  • New AG-Node1 (One NIC: 10.20.11.2/255.255.254.0)

  • New AG-Node2 (One NIC: 10.22.11.1/255.255.254.0)


I've read that this would be considered as an "AlwaysOn Multi-subnet" scenario (since nodes belong to different subnets).



Question:



Do I really have to treat this as an "AlwaysOn AG Multi subnet" even when all required routing is already implemented at networking device level and computers can all reach each other?



I've read that Routing and Remote Access is supposed to be deployed and configured but I do not get why this would be necessary since the routing is already implemented at networking device level.










share|improve this question

























  • Please add the subnet masks for the IPv4 addresses, otherwise it's possible those might all be on the same subnet.

    – Sean Gallardy
    20 hours ago











  • @SeanGallardy Added, thanks.

    – dsuy
    20 hours ago
















1















Context



I'm setting up a 2-node AlwaysOn Availability Group (SQL Server 2017 Enterprise) with the following setup:




  • Existing DC+DNS (One NIC: 10.20.11.1/255.255.254.0)

  • New AG-Node1 (One NIC: 10.20.11.2/255.255.254.0)

  • New AG-Node2 (One NIC: 10.22.11.1/255.255.254.0)


I've read that this would be considered as an "AlwaysOn Multi-subnet" scenario (since nodes belong to different subnets).



Question:



Do I really have to treat this as an "AlwaysOn AG Multi subnet" even when all required routing is already implemented at networking device level and computers can all reach each other?



I've read that Routing and Remote Access is supposed to be deployed and configured but I do not get why this would be necessary since the routing is already implemented at networking device level.










share|improve this question

























  • Please add the subnet masks for the IPv4 addresses, otherwise it's possible those might all be on the same subnet.

    – Sean Gallardy
    20 hours ago











  • @SeanGallardy Added, thanks.

    – dsuy
    20 hours ago














1












1








1








Context



I'm setting up a 2-node AlwaysOn Availability Group (SQL Server 2017 Enterprise) with the following setup:




  • Existing DC+DNS (One NIC: 10.20.11.1/255.255.254.0)

  • New AG-Node1 (One NIC: 10.20.11.2/255.255.254.0)

  • New AG-Node2 (One NIC: 10.22.11.1/255.255.254.0)


I've read that this would be considered as an "AlwaysOn Multi-subnet" scenario (since nodes belong to different subnets).



Question:



Do I really have to treat this as an "AlwaysOn AG Multi subnet" even when all required routing is already implemented at networking device level and computers can all reach each other?



I've read that Routing and Remote Access is supposed to be deployed and configured but I do not get why this would be necessary since the routing is already implemented at networking device level.










share|improve this question
















Context



I'm setting up a 2-node AlwaysOn Availability Group (SQL Server 2017 Enterprise) with the following setup:




  • Existing DC+DNS (One NIC: 10.20.11.1/255.255.254.0)

  • New AG-Node1 (One NIC: 10.20.11.2/255.255.254.0)

  • New AG-Node2 (One NIC: 10.22.11.1/255.255.254.0)


I've read that this would be considered as an "AlwaysOn Multi-subnet" scenario (since nodes belong to different subnets).



Question:



Do I really have to treat this as an "AlwaysOn AG Multi subnet" even when all required routing is already implemented at networking device level and computers can all reach each other?



I've read that Routing and Remote Access is supposed to be deployed and configured but I do not get why this would be necessary since the routing is already implemented at networking device level.







sql-server availability-groups network






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share|improve this question




share|improve this question








edited 15 hours ago









Tony Hinkle

2,5051422




2,5051422










asked 20 hours ago









dsuydsuy

162




162













  • Please add the subnet masks for the IPv4 addresses, otherwise it's possible those might all be on the same subnet.

    – Sean Gallardy
    20 hours ago











  • @SeanGallardy Added, thanks.

    – dsuy
    20 hours ago



















  • Please add the subnet masks for the IPv4 addresses, otherwise it's possible those might all be on the same subnet.

    – Sean Gallardy
    20 hours ago











  • @SeanGallardy Added, thanks.

    – dsuy
    20 hours ago

















Please add the subnet masks for the IPv4 addresses, otherwise it's possible those might all be on the same subnet.

– Sean Gallardy
20 hours ago





Please add the subnet masks for the IPv4 addresses, otherwise it's possible those might all be on the same subnet.

– Sean Gallardy
20 hours ago













@SeanGallardy Added, thanks.

– dsuy
20 hours ago





@SeanGallardy Added, thanks.

– dsuy
20 hours ago










1 Answer
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Do I really have to treat this as an "AlwaysOn AG Multi subnet" even when all required routing is already implemented at networking device level and computers can all reach each other?




Yes. SQL Server isn't doing any "routing" at the network level, it's not a layer-3 device... However, if you don't treat it as a "multi-subnet cluster" then you can get yourself into some time-out causing situations. While the situations are easily rectifiable, why not save the trouble and set everything up the first time, then not have to go back and change things?




I've read that Routing and Remote Access is supposed to be deployed and configured but I do not get why this would be necessary since the routing is already implemented at networking device level.




I don't know why someone is telling you to setup RRAS... unless it's for some local repro environment, such as the one on my laptop that doesn't have any routing devices as it's all internal virtual machines. This doesn't make any sense unless you're using RRAS as the routing device (software router).



Either way, this is all network design and has nothing specifically to do with SQL Server.






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    Do I really have to treat this as an "AlwaysOn AG Multi subnet" even when all required routing is already implemented at networking device level and computers can all reach each other?




    Yes. SQL Server isn't doing any "routing" at the network level, it's not a layer-3 device... However, if you don't treat it as a "multi-subnet cluster" then you can get yourself into some time-out causing situations. While the situations are easily rectifiable, why not save the trouble and set everything up the first time, then not have to go back and change things?




    I've read that Routing and Remote Access is supposed to be deployed and configured but I do not get why this would be necessary since the routing is already implemented at networking device level.




    I don't know why someone is telling you to setup RRAS... unless it's for some local repro environment, such as the one on my laptop that doesn't have any routing devices as it's all internal virtual machines. This doesn't make any sense unless you're using RRAS as the routing device (software router).



    Either way, this is all network design and has nothing specifically to do with SQL Server.






    share|improve this answer




























      3















      Do I really have to treat this as an "AlwaysOn AG Multi subnet" even when all required routing is already implemented at networking device level and computers can all reach each other?




      Yes. SQL Server isn't doing any "routing" at the network level, it's not a layer-3 device... However, if you don't treat it as a "multi-subnet cluster" then you can get yourself into some time-out causing situations. While the situations are easily rectifiable, why not save the trouble and set everything up the first time, then not have to go back and change things?




      I've read that Routing and Remote Access is supposed to be deployed and configured but I do not get why this would be necessary since the routing is already implemented at networking device level.




      I don't know why someone is telling you to setup RRAS... unless it's for some local repro environment, such as the one on my laptop that doesn't have any routing devices as it's all internal virtual machines. This doesn't make any sense unless you're using RRAS as the routing device (software router).



      Either way, this is all network design and has nothing specifically to do with SQL Server.






      share|improve this answer


























        3












        3








        3








        Do I really have to treat this as an "AlwaysOn AG Multi subnet" even when all required routing is already implemented at networking device level and computers can all reach each other?




        Yes. SQL Server isn't doing any "routing" at the network level, it's not a layer-3 device... However, if you don't treat it as a "multi-subnet cluster" then you can get yourself into some time-out causing situations. While the situations are easily rectifiable, why not save the trouble and set everything up the first time, then not have to go back and change things?




        I've read that Routing and Remote Access is supposed to be deployed and configured but I do not get why this would be necessary since the routing is already implemented at networking device level.




        I don't know why someone is telling you to setup RRAS... unless it's for some local repro environment, such as the one on my laptop that doesn't have any routing devices as it's all internal virtual machines. This doesn't make any sense unless you're using RRAS as the routing device (software router).



        Either way, this is all network design and has nothing specifically to do with SQL Server.






        share|improve this answer














        Do I really have to treat this as an "AlwaysOn AG Multi subnet" even when all required routing is already implemented at networking device level and computers can all reach each other?




        Yes. SQL Server isn't doing any "routing" at the network level, it's not a layer-3 device... However, if you don't treat it as a "multi-subnet cluster" then you can get yourself into some time-out causing situations. While the situations are easily rectifiable, why not save the trouble and set everything up the first time, then not have to go back and change things?




        I've read that Routing and Remote Access is supposed to be deployed and configured but I do not get why this would be necessary since the routing is already implemented at networking device level.




        I don't know why someone is telling you to setup RRAS... unless it's for some local repro environment, such as the one on my laptop that doesn't have any routing devices as it's all internal virtual machines. This doesn't make any sense unless you're using RRAS as the routing device (software router).



        Either way, this is all network design and has nothing specifically to do with SQL Server.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 19 hours ago









        Sean GallardySean Gallardy

        16k22548




        16k22548






























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