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Two Routers on the Same Subnet

Two Routers on the Same Subnet

Two Routers on the Same Subnet

(OP)
We have just installed a new Cisco 2811 on a different private IP from our primary gateway and configured it with another public IP so that we now have two gateways to the internet. This works well.
The problem is VPN connections. At first when I setup the VPN on the Cisco Router and established a connection, I could not see the servers. I could see other workstations with shares.
 After some trial and error I found out that the reason that I was not seeing the other computers was that their Default Gateway was automatically removing the new static gateway assignment. An IPCONFIG /RENEW fixed this but as soon as a computer connected from the other gate way it would cause the new gateway assignment to disappear.
So now I am trying to use two NICs with different IPs and Gateways and now the second NIC is losing the Cisco routers gateway. It just goes blank in the IPCONFIG...

Windows IP Configuration
Ethernet adapter Local Area Connection 2:
   Connection-specific DNS Suffix  . :
   IP Address. . . . . . . . . . . . : 10.100.100.8
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 10.100.100.1
                                       10.100.100.2
Ethernet adapter Local Area Connection:
   Connection-specific DNS Suffix  . :
   IP Address. . . . . . . . . . . . : 10.100.100.48
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . :

I checked my routing tables and both gateways are in there for both NICs...

===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0     10.100.100.1    10.100.100.48     10
          0.0.0.0          0.0.0.0     10.100.100.1     10.100.100.8     10
          0.0.0.0          0.0.0.0     10.100.100.2     10.100.100.8     10
          0.0.0.0          0.0.0.0     10.100.100.2    10.100.100.48     10
     10.100.100.0    255.255.255.0     10.100.100.8     10.100.100.8     10
     10.100.100.0    255.255.255.0    10.100.100.48    10.100.100.48     10
     10.100.100.8  255.255.255.255        127.0.0.1        127.0.0.1     10
    10.100.100.48  255.255.255.255        127.0.0.1        127.0.0.1     10
   10.255.255.255  255.255.255.255     10.100.100.8     10.100.100.8     10
   10.255.255.255  255.255.255.255    10.100.100.48    10.100.100.48     10
        127.0.0.0        255.0.0.0        127.0.0.1        127.0.0.1      1
        224.0.0.0        240.0.0.0     10.100.100.8     10.100.100.8     10
        224.0.0.0        240.0.0.0    10.100.100.48    10.100.100.48     10
  255.255.255.255  255.255.255.255     10.100.100.8     10.100.100.8      1
  255.255.255.255  255.255.255.255    10.100.100.48    10.100.100.48      1
Default Gateway:   10.100.100.1
===========================================================================
Persistent Routes:  None

The routing table seems to have a default gateway which is off on its own but I do not see a way of adding to this or changing it.
I suck at this networking stuff so if any one can help me out it would be appreciated.
 

RE: Two Routers on the Same Subnet

I am not a windows network expert, but I think you cannot have both gateways 'active' at the same time on a host. What most people do is stick a router to negotiate between the WANS.  The problem is without twiddling the routing metrics (on the hosts) 2 equal routes will probably round-robin.

RE: Two Routers on the Same Subnet

you can just have one default gateway, and the default gateway priority is according to the advanced setting in network connection. so you just leave one default gateway in one NIC while empty at other NICs.

if you need to have different routing on the same subnet, you have to do routing on the primary gateway, or

configure the permanent routes at the windows

 


Porkchop

CISSP
MCITP : Enterprise Administrator  
 

RE: Two Routers on the Same Subnet

(OP)
I figured out what My Problem was. I am using Windows 2003 Server as my DHCP server and I had Resorvations setup for these NICs. It appears that Windows can only specify one Router in their  resorvations with a set list of Gateways. This had set the default order of the Gateways to 10.100.100.1, 10.100.100.2 for all of the resorvations and it over road the local settings on the NICs when the TTL was up. I just simply took out the resorvations and this fixed my problem.

Thanks for the Input.

RE: Two Routers on the Same Subnet

By the way, both those who wonder you can have as many gateways on a windows machine as you'd like.

The way to do it is to specify the first gateway in the tcp/ip propreties (the standard way) and the rest of the gateways as persistant routes.

example:
route ADD 157.0.0.0 MASK 255.0.0.0  157.55.80.1 -p

RE: Two Routers on the Same Subnet

Can't you also just add them in the GUI in the Advanced TCP/IP properties?

Dave Shackelford
ThirdTier.net

RE: Two Routers on the Same Subnet

I have always just specified multiple gateways as persistent routes without ever having a problem.  

Network+ Inet+ MCP

RE: Two Routers on the Same Subnet

(OP)
Just an Update on this. I setup static routes in the "Routing and Remote Access" because the persistent routes did not solve the problem.

I think it is do to one Windows Networking needs to be fixed and two when our PTP VPN with our Tucson office connected it redo the IP Tables with the rout to the the 10.100.100.1 Gateway.

The "Routing and Remote Access" fixed this problem for Client VPN connections on the 10.100.100.2 gateway but now the PTP VPN connection on the Gateway 10.100.100.1 is not working.

It seems that you can only have one route at a time. I would like to be able to have one NIC with a route to the 10.100.100.1 gateway and another NIC to the 10.100.100.2 gateway to separate the the traffic.

Any suggestions?

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