W2k8 basic IP forwarding

[quikah]

OK, this is driving me batty.

I have a very simple network:

A -- B -- C

A IP 192.168.1.20
B (2 NICs) IP is 192.168.1.3 & 192.168.2.3
C IP 192.168.2.20

B is running W2k8 (all updates installed, firewall off). I can ping from A<->B and B<->C.

I set IPenableRouter=1 in registry

Set A GW to 192.168.1.3
Set C GW to 192.168.2.3

From A I can ping 192.168.1.3 & 192.168.2.3
From B I can only ping A, but not C
C cannot ping B

Any ideas?

---

ugg, wrong forum, sorry.

if mod sees this move to networking

Moved from OS to Networking
-ViRGE

 

[imagoon]

Have you installed the "routing and remote access" role?

 

[bobdole369]

What does the routing table on B look like? (i.e. is there a default gateway set?)
Repeat for A and C.

 

[drebo]

If C and B can't ping each other, you need to look at your config on C, not B.

 

[bobdole369]

If C and B can't ping each other, you need to look at your config on C, not B.

Not if b is sending replies out to its dg (might be on a's subnet)

 

[drebo]

Not if b is sending replies out to its dg (might be on a's subnet)

Er...no.

According to his diagram and explanation (which is garbage, admittedly), B and C share an interface on the same segment, and thus should have the same subnet and should be able to talk. B is the default gateway of C.

You cannot have a default gateway in a subnet other than one you are connected to.

 

[quikah]

Have you installed the "routing and remote access" role?

no, I am under the impression that that is only required if I wanted to do dynamic routing.

I am using the IPenableRouter registry flag to enable IP forwarding.

I tore my testbed down, so I don't have this setup anymore, I will try this again tomorrow.

Just to clarify for the others:

With the default config A & C can ping B as expected. B has 2 NICs, 1 on each subnet. When I enable the IPenableRouter registry flag on B it loses all connectivity to C's subnet.

I have done this on Linux before, but the last time I tried this on Windows was NT4 I think.

 

[yinan]

Enable RRAS and all of your problems will go away.

 

[bobdole369]

no, I am under the impression that that is only required if I wanted to do dynamic routing.

I am using the IPenableRouter registry flag to enable IP forwarding.

I tore my testbed down, so I don't have this setup anymore, I will try this again tomorrow.

Just to clarify for the others:

With the default config A & C can ping B as expected. B has 2 NICs, 1 on each subnet. When I enable the IPenableRouter registry flag on B it loses all connectivity to C's subnet.

I have done this on Linux before, but the last time I tried this on Windows was NT4 I think.

Er...no.

According to his diagram and explanation (which is garbage, admittedly), B and C share an interface on the same segment, and thus should have the same subnet and should be able to talk. B is the default gateway of C.

Aye of course this is correct as B and C are on the same segment (sorry I read that too fast lol)

You can always run wireshark on all the units to see what the packets are doing.

 

[imagoon]

no, I am under the impression that that is only required if I wanted to do dynamic routing.

I am using the IPenableRouter registry flag to enable IP forwarding.

I tore my testbed down, so I don't have this setup anymore, I will try this again tomorrow.

Just to clarify for the others:

With the default config A & C can ping B as expected. B has 2 NICs, 1 on each subnet. When I enable the IPenableRouter registry flag on B it loses all connectivity to C's subnet.

I have done this on Linux before, but the last time I tried this on Windows was NT4 I think.

My only experience at the 'Windows level routing' has only be through RRAS where it wasn't that bad to set up. 2008(R2) has done a lot to modularize the OS and tons of items that used to come by default are simply missing or disabled until you add the feature or role.

Also it is better to set that flag via netsh.

 

[quikah]

RRAS is way too much for what I need. I just need a very simple way to route one system from one subnet to another.

Well, I rebuilt it and now it is working. I don't know why it wasn't working before, same settings...

Oh well, at least I know it works.

 

[Nothinman]

Multihomed Windows servers are usually questionable at best, be glad you got it working at all. =)