DFS Replication on secondary NIC

Hello group !

I have to Win2k3 R2 DCs replicating some folders using DFS
replication.
They both have two nics and are sitting next to each other, so I
would like them to use this secondary NIC when they talk to each
other (mostly for replication, because it takes a lot of bandwidth).

Server1 IP is 10.0.1.1
Server2 IP is 10.0.1.2

I have set the second NICs IP as 10.0.2.1 (server1) and 10.0.2.2
(server2).

Now, I know I have something to change in the metric of the
interfaces.
I have tried :
route ADD 10.0.2.2 MASK 255.255.255.255 10.0.2.1 METRIC 5 IF 2
but I have an error message "The route addition failed: Either the
interface index is wrong or the gateway does not lie on the same
network as the interface. Check the IP Address Table for the machine."
If I try without specifying the interface :
route ADD 10.0.2.2 MASK 255.255.255.255 10.0.2.1 METRIC 5
"The route addition failed: The parameter is incorrect."

What is the correct way to do this ?

Thanks a lot !

PS : follow-ups to dfs_frs please

--
Arnaud

Hi Arnaud!

What's the subnet mask for the NICs?
If you have a NIC in server1 with IP 10.0.1.1 and Server2 has IP 10.0.1.2
they can talk as long as they have the same subnet mask - the fact that you
have other NICs as well makes no difference, the OS will choose the
appropriate NIC.
Since you have another NIC with IP 10.0.2.x you need to differentiate the
networks by having a subnet mask of at least 24 bits (255.255.255.0 or more
specific).

Use route print to see all the entries you have; it shouldn't be needed to
add more manually in this scenario.


"Arnaud Lesauvage" wrote:

> Hello group !
>
> I have to Win2k3 R2 DCs replicating some folders using DFS
> replication.
> They both have two nics and are sitting next to each other, so I
> would like them to use this secondary NIC when they talk to each
> other (mostly for replication, because it takes a lot of bandwidth).
>
> Server1 IP is 10.0.1.1
> Server2 IP is 10.0.1.2
>
> I have set the second NICs IP as 10.0.2.1 (server1) and 10.0.2.2
> (server2).
>
> Now, I know I have something to change in the metric of the
> interfaces.
> I have tried :
> route ADD 10.0.2.2 MASK 255.255.255.255 10.0.2.1 METRIC 5 IF 2
> but I have an error message "The route addition failed: Either the
> interface index is wrong or the gateway does not lie on the same
> network as the interface. Check the IP Address Table for the machine."
> If I try without specifying the interface :
> route ADD 10.0.2.2 MASK 255.255.255.255 10.0.2.1 METRIC 5
> "The route addition failed: The parameter is incorrect."
>
> What is the correct way to do this ?
>
> Thanks a lot !
>
> PS : follow-ups to dfs_frs please
>
> --
> Arnaud
>

Martin Claesson (MSFT) wrote:
> Hi Arnaud!
>
> What's the subnet mask for the NICs?
> If you have a NIC in server1 with IP 10.0.1.1 and Server2 has IP 10.0.1.2
> they can talk as long as they have the same subnet mask - the fact that you
> have other NICs as well makes no difference, the OS will choose the
> appropriate NIC.
> Since you have another NIC with IP 10.0.2.x you need to differentiate the
> networks by having a subnet mask of at least 24 bits (255.255.255.0 or more
> specific).
>
> Use route print to see all the entries you have; it shouldn't be needed to
> add more manually in this scenario.



Hi Martin !
Thanks for your answer !

Indeed, both NICs are on the same network. Both have a mask of
255.0.0.0.
The NIC connected to the LAN should stay on that network because
workstations are configured that way.
Do you mean that I should change the mask of the other NIC to
255.255.255.0 ?
Is this enough ?

I wondered about another issue : both IPs would be registered in
DNS, but only 1.0.1.1 should be used by workstations to
communicate with the server. How can I prevent them from trying to
communicate with 10.0.2.1 ?

I though I could use another private range like 192.168.0.1 for
this secondary conncection. Would this make the routing easier ?

Regards
--
Arnaud

Hi!

In your case you need to change the network and the subnet mask for the
replication network. The LAN uses 10.x.x.x (all addresses that start with
10.something) because you have a subnet mask of 255.0.0.0; so you are
allowing for 16.7 million machines on the LAN subnet. Because of this you
need to choose a completely different subnet for the replication network,
e.g. 192.168.x.x (like you suggested) with a subnet mask of e.g
255.255.255.0. So the second NIC on Server1 can be 192.168.0.1 and the second
NIC on Server2 can be 192.168.0.2. Both with a subnet mask of 255.255.255.0.

If you only intend to have 2 servers on the replication network I suggest
you use a cross-over cable (provided the distance is less than 100 meters) or
else a separate switch so you don't use bandwidth from the LANs switch.
If you later need to expand it does make routing easier to have different
networks like this.

Thanks,
Martin.


"Arnaud Lesauvage" wrote:

> Martin Claesson (MSFT) wrote:
> > Hi Arnaud!
> >
> > What's the subnet mask for the NICs?
> > If you have a NIC in server1 with IP 10.0.1.1 and Server2 has IP 10.0.1.2
> > they can talk as long as they have the same subnet mask - the fact that you
> > have other NICs as well makes no difference, the OS will choose the
> > appropriate NIC.
> > Since you have another NIC with IP 10.0.2.x you need to differentiate the
> > networks by having a subnet mask of at least 24 bits (255.255.255.0 or more
> > specific).
> >
> > Use route print to see all the entries you have; it shouldn't be needed to
> > add more manually in this scenario.
>
>
>
> Hi Martin !
> Thanks for your answer !
>
> Indeed, both NICs are on the same network. Both have a mask of
> 255.0.0.0.
> The NIC connected to the LAN should stay on that network because
> workstations are configured that way.
> Do you mean that I should change the mask of the other NIC to
> 255.255.255.0 ?
> Is this enough ?
>
> I wondered about another issue : both IPs would be registered in
> DNS, but only 1.0.1.1 should be used by workstations to
> communicate with the server. How can I prevent them from trying to
> communicate with 10.0.2.1 ?
>
> I though I could use another private range like 192.168.0.1 for
> this secondary conncection. Would this make the routing easier ?
>
> Regards
> --
> Arnaud
>

Martin Claesson (MSFT) wrote:
> In your case you need to change the network and the subnet mask for the
> replication network. The LAN uses 10.x.x.x (all addresses that start with
> 10.something) because you have a subnet mask of 255.0.0.0; so you are
> allowing for 16.7 million machines on the LAN subnet. Because of this you
> need to choose a completely different subnet for the replication network,
> e.g. 192.168.x.x (like you suggested) with a subnet mask of e.g
> 255.255.255.0. So the second NIC on Server1 can be 192.168.0.1 and the second
> NIC on Server2 can be 192.168.0.2. Both with a subnet mask of 255.255.255.0.
>
> If you only intend to have 2 servers on the replication network I suggest
> you use a cross-over cable (provided the distance is less than 100 meters) or
> else a separate switch so you don't use bandwidth from the LANs switch.
> If you later need to expand it does make routing easier to have different
> networks like this.


Thanks Martin !
Indeed, I have only 2 servers and they are sitting next to each
other, so I will use a crossover cable.
I will try to set them up on a 192.168.0.x subnet as suggested.
Thanks again !

--
Arnaud