0

I have two multi-homed servers connected to each other via a private network and also via a public network. I cannot get traffic to go across the private network. The servers only use the public network NICs to communicate with each other. These servers are Windows servers hosting SQL Server Availability group. I added entries in the host file so that Host names resolve to the IP addresses on the private network. Pinging the host names resolve to the private IP, but however copying files and things higher in the stack seem to use the public IPs.

I've pasted the routing table and ipconfigs below.

SQL1 Server 1 public 10.149.10.85 private 192.168.10.27

SQL Server 2 public 10.149.10.86 private 192.168.10.26

Routing table and ipconfig SQL Server 1

C:\windows\system32>route print

===========================================================================

Interface List

  2...80 18 44 df 77 3b ......Broadcom NetXtreme Gigabit Ethernet #2

  4...02 e3 de 27 dc 51 ......Microsoft Failover Cluster Virtual Adapter

  3...80 18 44 df 77 39 ......Microsoft Network Adapter Multiplexor Driver

  7...80 18 44 df 77 3a ......Broadcom NetXtreme Gigabit Ethernet #3

  1...........................Software Loopback Interface 1

10...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter

11...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2

  9...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3

===========================================================================



IPv4 Route Table

===========================================================================

Active Routes:

Network Destination        Netmask          Gateway       Interface  Metric

       10.149.0.0    255.255.224.0         On-link      10.149.10.85    276

     10.149.10.28  255.255.255.255         On-link      10.149.10.85    276

     10.149.10.85  255.255.255.255         On-link      10.149.10.85    276

    10.149.31.255  255.255.255.255         On-link      10.149.10.85    276

        127.0.0.0        255.0.0.0         On-link         127.0.0.1    331

        127.0.0.1  255.255.255.255         On-link         127.0.0.1    331

  127.255.255.255  255.255.255.255         On-link         127.0.0.1    331

      169.254.0.0      255.255.0.0         On-link      169.254.1.25    271

     169.254.1.25  255.255.255.255         On-link      169.254.1.25    271

  169.254.255.255  255.255.255.255         On-link      169.254.1.25    271

      192.168.0.0      255.255.0.0         On-link     192.168.10.27    281

    192.168.10.27  255.255.255.255         On-link     192.168.10.27    281

  192.168.255.255  255.255.255.255         On-link     192.168.10.27    281

        224.0.0.0        240.0.0.0         On-link         127.0.0.1    331

        224.0.0.0        240.0.0.0         On-link     192.168.10.27    281

        224.0.0.0        240.0.0.0         On-link      169.254.1.25    271

        224.0.0.0        240.0.0.0         On-link      10.149.10.85    276

  255.255.255.255  255.255.255.255         On-link         127.0.0.1    331

  255.255.255.255  255.255.255.255         On-link     192.168.10.27    281

  255.255.255.255  255.255.255.255         On-link      169.254.1.25    271

  255.255.255.255  255.255.255.255         On-link      10.149.10.85    276

===========================================================================

Persistent Routes:

  Network Address          Netmask  Gateway Address  Metric

    192.168.10.26      255.255.0.0    192.168.10.26       1

    192.168.10.26      255.255.0.0    192.168.10.27       1

    192.168.10.26    255.255.255.0    192.168.10.26       1

===========================================================================



IPv6 Route Table

===========================================================================

Active Routes:

If Metric Network Destination      Gateway

  1    331 ::1/128                  On-link

  4    271 fe80::/64                On-link

  4    271 fe80::288d:f706:a1df:6aa2/128

                                    On-link

  1    331 ff00::/8                 On-link

  4    271 ff00::/8                 On-link

===========================================================================

Persistent Routes:

  None




C:\windows\system32>ipconfig /all



Windows IP Configuration



   Host Name . . . . . . . . . . . . : SQL1

   Primary Dns Suffix  . . . . . . . : mydomain.com

   Node Type . . . . . . . . . . . . : Hybrid

   IP Routing Enabled. . . . . . . . : No

   WINS Proxy Enabled. . . . . . . . : No

   DNS Suffix Search List. . . . . . : mydomain.com

                                       mydomain.com



Ethernet adapter NIC4:



   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Broadcom NetXtreme Gigabit Ethernet #2

   Physical Address. . . . . . . . . : 80-18-44-DF-77-3B

   DHCP Enabled. . . . . . . . . . . : Yes

   Autoconfiguration Enabled . . . . : Yes



Tunnel adapter Local Area Connection* 3:



   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Microsoft Failover Cluster Virtual Adapter

   Physical Address. . . . . . . . . : 02-E3-DE-27-DC-51

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes

   Link-local IPv6 Address . . . . . : fe80::288d:f706:a1df:6aa2%4(Preferred)

   IPv4 Address. . . . . . . . . . . : 169.254.1.25(Preferred)

   Subnet Mask . . . . . . . . . . . : 255.255.0.0

   Default Gateway . . . . . . . . . :

   DHCPv6 IAID . . . . . . . . . . . : 67290756

   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-21-77-91-3B-80-18-44-DF-77-38

   NetBIOS over Tcpip. . . . . . . . : Enabled



Ethernet adapter Team 1:



   Connection-specific DNS Suffix  . : mydomain.com

   Description . . . . . . . . . . . : Microsoft Network Adapter Multiplexor Driver

   Physical Address. . . . . . . . . : 80-18-44-DF-77-39

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes

   IPv4 Address. . . . . . . . . . . : 10.149.10.85(Preferred)

   Subnet Mask . . . . . . . . . . . : 255.255.224.0

   IPv4 Address. . . . . . . . . . . : 10.149.10.28(Preferred)

   Subnet Mask . . . . . . . . . . . : 255.255.224.0

   Default Gateway . . . . . . . . . :

   DNS Servers . . . . . . . . . . . : 10.149.10.11

                                       10.149.10.12

   NetBIOS over Tcpip. . . . . . . . : Enabled



Ethernet adapter NIC3:



   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Broadcom NetXtreme Gigabit Ethernet #3

   Physical Address. . . . . . . . . : 80-18-44-DF-77-3A

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes

   IPv4 Address. . . . . . . . . . . : 192.168.10.27(Preferred)

   Subnet Mask . . . . . . . . . . . : 255.255.0.0

   Default Gateway . . . . . . . . . :

   NetBIOS over Tcpip. . . . . . . . : Enabled



Tunnel adapter isatap.mydomain.com:



   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . : mydomain.com

   Description . . . . . . . . . . . : Microsoft ISATAP Adapter

   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes



Tunnel adapter isatap.{D4F4B8DA-8B70-4022-8494-448BD24C80E7}:



   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2

   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes



Tunnel adapter isatap.{308FA901-D05C-4A6E-9E87-CC4434A82133}:



   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Microsoft ISATAP Adapter #3

   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes

Routing table and ipconfig SQL Server 2

C:\windows\system32>route print

===========================================================================

Interface List

  3...80 18 44 df 80 b3 ......Broadcom NetXtreme Gigabit Ethernet #4

  4...02 0e ce 5d 94 7a ......Microsoft Failover Cluster Virtual Adapter

10...80 18 44 df 80 b1 ......Microsoft Network Adapter Multiplexor Driver

  2...80 18 44 df 80 b2 ......Broadcom NetXtreme Gigabit Ethernet

  1...........................Software Loopback Interface 1

  8...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter

  6...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2

  9...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3

===========================================================================



IPv4 Route Table

===========================================================================

Active Routes:

Network Destination        Netmask          Gateway       Interface  Metric

       10.149.0.0    255.255.224.0         On-link      10.149.10.86    276

     10.149.10.29  255.255.255.255         On-link      10.149.10.86    276

     10.149.10.86  255.255.255.255         On-link      10.149.10.86    276

    10.149.31.255  255.255.255.255         On-link      10.149.10.86    276

        127.0.0.0        255.0.0.0         On-link         127.0.0.1    331

        127.0.0.1  255.255.255.255         On-link         127.0.0.1    331

  127.255.255.255  255.255.255.255         On-link         127.0.0.1    331

      169.254.0.0      255.255.0.0         On-link      169.254.2.50    271

     169.254.2.50  255.255.255.255         On-link      169.254.2.50    271

  169.254.255.255  255.255.255.255         On-link      169.254.2.50    271

      192.168.0.0      255.255.0.0         On-link     192.168.10.26    281

    192.168.10.26  255.255.255.255         On-link     192.168.10.26    281

  192.168.255.255  255.255.255.255         On-link     192.168.10.26    281

        224.0.0.0        240.0.0.0         On-link         127.0.0.1    331

        224.0.0.0        240.0.0.0         On-link     192.168.10.26    281

        224.0.0.0        240.0.0.0         On-link      169.254.2.50    271

        224.0.0.0        240.0.0.0         On-link      10.149.10.86    276

  255.255.255.255  255.255.255.255         On-link         127.0.0.1    331

  255.255.255.255  255.255.255.255         On-link     192.168.10.26    281

  255.255.255.255  255.255.255.255         On-link      169.254.2.50    271

  255.255.255.255  255.255.255.255         On-link      10.149.10.86    276

===========================================================================

Persistent Routes:

  Network Address          Netmask  Gateway Address  Metric

    192.168.10.27      255.255.0.0    192.168.10.27       1

    192.168.10.27      255.255.0.0    192.168.10.26       1

    192.168.10.27    255.255.255.0    192.168.10.27       1

===========================================================================



IPv6 Route Table

===========================================================================

Active Routes:

If Metric Network Destination      Gateway

  1    331 ::1/128                  On-link

  4    271 fe80::/64                On-link

  4    271 fe80::8076:a706:66a8:8bd2/128

                                    On-link

  1    331 ff00::/8                 On-link

  4    271 ff00::/8                 On-link

===========================================================================

Persistent Routes:

  None








C:\windows\system32>ipconfig /all



Windows IP Configuration



   Host Name . . . . . . . . . . . . : SQL2

   Primary Dns Suffix  . . . . . . . : mydomain.com

   Node Type . . . . . . . . . . . . : Hybrid

   IP Routing Enabled. . . . . . . . : No

   WINS Proxy Enabled. . . . . . . . : No

   DNS Suffix Search List. . . . . . : mydomain.com

                                       mydomain.com



Ethernet adapter NIC4:



   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Broadcom NetXtreme Gigabit Ethernet #4

   Physical Address. . . . . . . . . : 80-18-44-DF-80-B3

   DHCP Enabled. . . . . . . . . . . : Yes

   Autoconfiguration Enabled . . . . : Yes



Tunnel adapter Local Area Connection* 3:



   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Microsoft Failover Cluster Virtual Adapter

   Physical Address. . . . . . . . . : 02-0E-CE-5D-94-7A

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes

   Link-local IPv6 Address . . . . . : fe80::8076:a706:66a8:8bd2%4(Preferred)

   IPv4 Address. . . . . . . . . . . : 169.254.2.50(Preferred)

   Subnet Mask . . . . . . . . . . . : 255.255.0.0

   Default Gateway . . . . . . . . . :

   DHCPv6 IAID . . . . . . . . . . . : 67292029

   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-21-76-80-77-80-18-44-DF-80-B2

   NetBIOS over Tcpip. . . . . . . . : Enabled



Ethernet adapter Team 1:



   Connection-specific DNS Suffix  . : mydomain.com

   Description . . . . . . . . . . . : Microsoft Network Adapter Multiplexor Driver

   Physical Address. . . . . . . . . : 80-18-44-DF-80-B1

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes

   IPv4 Address. . . . . . . . . . . : 10.149.10.86(Preferred)

   Subnet Mask . . . . . . . . . . . : 255.255.224.0

   IPv4 Address. . . . . . . . . . . : 10.149.10.29(Preferred)

   Subnet Mask . . . . . . . . . . . : 255.255.224.0

   Default Gateway . . . . . . . . . :

   DNS Servers . . . . . . . . . . . : 10.149.10.11

                                       10.149.10.12

   NetBIOS over Tcpip. . . . . . . . : Enabled



Ethernet adapter NIC3:



   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Broadcom NetXtreme Gigabit Ethernet

   Physical Address. . . . . . . . . : 80-18-44-DF-80-B2

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes

   IPv4 Address. . . . . . . . . . . : 192.168.10.26(Preferred)

   Subnet Mask . . . . . . . . . . . : 255.255.0.0

   Default Gateway . . . . . . . . . :

   NetBIOS over Tcpip. . . . . . . . : Enabled



Tunnel adapter isatap.mydomain.com:



   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . : mydomain.com

   Description . . . . . . . . . . . : Microsoft ISATAP Adapter

   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes



Tunnel adapter isatap.{4F5724BA-E676-4C22-A804-E28360E94AFC}:



   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2

   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes



Tunnel adapter isatap.{093FD353-FE5F-4FDC-A6E3-04DD46A18C82}:



   Media State . . . . . . . . . . . : Media disconnected

   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Microsoft ISATAP Adapter #3

   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0

   DHCP Enabled. . . . . . . . . . . : No

   Autoconfiguration Enabled . . . . : Yes
  • You have no 192.16. routes and you're asking why traffic isn't routed between 2 machines with 192.168. addresses? – symcbean Dec 28 '17 at 14:49
  • A 192.168.10.0/24 gateway isn't necessary for computers on-link to communicate with each other (and the 192.168.0.0/16 route does show as on-link). So that is good (and why you can ping). With windows your problem is going to be that it is preferring IPv6. Try the "prefer IPv4 over IPv6" fix-it from MS at support.microsoft.com/en-us/help/929852 and see if that helps. If it does, you can either work with that (preferring 4 over 6) or do some work to get your IPv6 subnets setup to handle your scenario the same way the v4 does – Ruscal Dec 28 '17 at 14:58
  • Also get rid of those persistent routes you added. They are conflicting and not needed. But the IPv6 comment by @Ruscal is a good catch I think. Not sure what symcbean is talking about, all the routes are there. – Appleoddity Dec 28 '17 at 15:02
1

I recreated your issue in a lab environ today. The problem I saw (which matched your description) was indeed caused by IPv6. The machines tried to talk to each other over IPv6 first, and they connected over the non-private link since that route had a lower cost (same net).

I ran the Microsoft FixIt-20166 to prefer IPv4 over IPv6 and that fixed the problem. Then, for giggles, I reverted the changes (there is a undo package on that same page) and manually adjusted the IPv6 addresses on the private link so they were on common net with no extra hops. After registering the IPv6 addresses in my DNS (I was using named references in SQL) then the traffic started using the private link via IPv6.

Unless you test and get different results, this is what I expect you are encountering as well. The IPv6 addresses are being used for the SQL-SQL communications, because windows prefers v6; and the IPv6 link over the public interface is being seen as lower cost than the private interface. That is causing the traffic to travel over the lower cost (public) interface. The way to change that would be to not prefer IPv6 (so the v4 family is used and your cost decreases on the private interface) or setup your IPv6 network on the private link so that the cost is decreased (both PCs on-net with one another).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.