Cannot Ping Internet with dual NICS on W2K Server

Posted on 2005-03-23
Medium Priority
Last Modified: 2013-11-09
I have a Win2k server used as an ATM switch with dual NICs. The premise is that my server will receive an ATM request from an ATM service provider using a frame relay through NIC 1. Then I switch that request, using proprietary software, through the second NIC to the Internet to my clients database server. Their server reply returns the same way through my second NIC and the its switched to NIC 1 back through the frame relay.

NIC 1 - Uses frame relay circuit to ATM Service Provider. Does not touch the Internet
IP address -
Subnet Mask -
Gateway -
No DNS addresses
Persistent route - mask

NIC 2 - Private IP behind my firewall and accesses the Internet
IP address -
Subnet mask -
Gateway - (Firewall)
DNS addresses configured for Internet access

This system worked great till my ATM provider changed their IP on the far side of the Frame relay circuit. All I did was change the Route Add to point to the new static IP using the same class C public IP on my NIC 1.

Persistent route - mask

Now I cannot ping or access the Internet with NIC 2. The pings get lost and never reach my firewall router. It seems that the static route I added with the Route Add command redirects the pings from NIC 2 to the frame relay circuit and then go to bit heaven. If I delete the static route through the command prompt then NIC 2 will ping and access the Internet successfully. Then I re-add the static route and all is golden till the Server needs to be rebooted and it starts all over again. I have worked around this by writing a small batch file that deletes the static route, pings an Internet address and then adds the static route back. Funny thing is I have another server setup the same way using another ATM service provider and it works great.

BTW, I have replaced the NICs and cabling and have disable IP routing on the server. I also added another static route pointing my private IP to the WAN side of my firewall in hopes of telling it where to go to access the Internet.


Question by:dennis1960
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LVL 13

Expert Comment

ID: 13618205
Does the routing table reflect the new IP Address after you enter the persistent route?
What is the table before the static route?
What is the table after the static route is entered?
LVL 41

Accepted Solution

stevenlewis earned 2000 total points
ID: 13618362
You have two default gateways setup, one for each NIC, and you can't do that
remove the default gateway on the LAN NIC, and use the route add to add the route to that network
this says 98, but applies here


When two network adapters are present in a computer (multihomed), a default gateway should only be assigned

to one of the network adapter's TCP/IP properties. If one of the network adapters is used to connect

to the Internet, the default gateway should be assigned to that network adapter. In many cases, the

default gateway, as well as the other necessary TCP/IP information is assigned automatically by the

Internet Service Provider by using Dynamic Host Configuration Protocol (DHCP). This can be confirmed

by using the IP Configuration utility (Winipcfg.exe) to view the TCP/IP properties for the network adapter

you are using to connect to the Internet.

For the network adapter that is connected only to the Local Area Network (LAN), such as a home or corporate

network, a static routing entry must be entered into the computer's routing table if the computer needs

to obtain access to network resources across a router or multiple routers. For example, if the router

interface on the same subnet has an IP address of and the router is connecting the

network to a network, the following command would need to be entered either at a command

prompt within Windows or from a batch file:


This command instructs Windows to send all traffic that is destined for the network to the interface on the router. To verify that the ROUTE ADD command was successful, use the ROUTE

PRINT command to view the current routing table. If multiple routers are being used on the LAN segment,

a separate ROUTE ADD is needed for each router.

Note that the routing entry is not persistent in Windows 98/95, even with the -p switch, and is lost

after you restart the computer. To have this entry automatically added for every Windows session, create

a batch file with the necessary ROUTE ADD command(s) and place it in the Windows StartUp folder to be

executed each time Windows starts.

If DHCP is used to assign IP addresses on the LAN, the DHCP server should be configured to not provide

a default gateway.

LVL 23

Expert Comment

ID: 13618972
Second steven -- There is no windows OS yet that is natively dual-homing capable.  It is part of the limited design of Microsoft developers who realy don't understand networking.  There is no reason why it cannot be done, but MS refuses to do it, probably because they don't know enough about networking to get it to work.

In your case, you cannot take in a data stream on one IP and send it out another.  The resolution of any client must be tied to a single IP, according to the IP rules.  You will note that bidirectional transport is capable on the internal network, but not on the internet-work.  That's because Novell designed the network transports which MS relies on for local networking.  IN contrast, the IP themology was designed to resolve to a single IP per client host.

I have tired what you're trying and it doesn't work.  TCP/IP is not directionally routable, nor natively bidirectionally homable.  Hope that makes sense, and sorry, steven if I overlapped, I just had to say this as I said it.

Author Comment

ID: 13621510
To confirm your suggestion, I need to remove the gateway address from NIC 1 but keep the static route for frame relay. If I remove the gateway how will my server know to point all packets to the router IP?
IP address -
Gateway - blank
DNS - blank
Route add -p mask (IP of ethernet port of router)

I will try this configuration today. What I don't understand is why the setup failed after changing the static route. As I said before, another server with NICs setup exactly the same way on the same subnets works without issue. The only difference is the static route and different Cisco routers.
I'll let you know if it solves my problem.


Expert Comment

ID: 13628133
Steve's got it right, you can't run two gateway's on Windows boxes. Leave your internet gateway there, and setup routes to your ATM IP's via the 100.2 gateway.
The route command would be: route add -p mask

So now when we have a packet going to an ip on the 199.199.199 segment, the server knows to push it through the 100.2 gateway.
Just add as many routes as there are segments you need to reach via the 100.2 gateway.

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