Need Help With Routing Issue

Can someone help me decipher a routing table and figure out why the routing
is going off course?

We have a Microsoft Proxy Server with internal interface 172.16.20.1 that
points at internal router 172.16.20.5. External interface is 10.0.0.6 and
points to external router 10.0.0.1.

What is happening is that winsock proxy client requests come to the
Microsoft Proxy Server, and the outbound requests to the Internet are being
redirected to the internal network's router. The internal network router
does ICMP redirects, and after about 20 seconds, the Microsoft Proxy Server
seems to get the point and then directs the request outbound on the correct
interface.

When the machine first boots the default router in the route print command
is the external router. Once this problem starts, the route print shows
the internal router as the default router, even though the metric for the
internal route is set to 2 and the metric for the external router is 1.

What would cause the machine to start favoring the internal router for
outgoing Internet requests? Is there a problem in the route table? Do we
need some persistent routes?

--
Will

Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.0.0.1 10.0.0.6 1
0.0.0.0 0.0.0.0 172.16.20.5 172.16.20.1 2
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
172.16.0.0 255.255.255.0 10.0.0.6 10.0.0.6 1
10.0.0.6 255.255.255.255 127.0.0.1 127.0.0.1 1
172.16.255.255 255.255.255.255 10.0.0.6 10.0.0.6 1
172.16.20.0 255.255.255.0 172.16.20.1 172.16.20.1 2
172.16.20.1 255.255.255.255 127.0.0.1 127.0.0.1 2
172.16.20.255 255.255.255.255 172.16.20.1 172.16.20.1 2
224.0.0.0 224.0.0.0 10.0.0.6 10.0.0.6 1
224.0.0.0 224.0.0.0 172.16.20.1 172.16.20.1 2
255.255.255.255 255.255.255.255 10.0.0.6 10.0.0.6 1
Default Gateway: 172.16.20.5
================================================== =========================
Persistent Routes:
None

Hi Will,

In most cases Windows server should only have one default gateway (there is
only one way out (to the internet)). If I read this correctly you should
remove the gateway that leads to 172.16.20.5.

If you have specific needs for routing traffic to internal router
(172.16.20.5) you should use persistent routes and not additional default
gateway.

One example of such route would be when you have 192.168.0.0 network behind
the 172.16.20.5 router. In this case you would add

route add -p 192.168.0.0 mask 255.255.255.0 172.16.20.5

on your server.

Here are few articles that talk about these issues...

Default gateways
http://www.microsoft.com/technet/pro...d3859f5b1.mspx

Default Gateway Behavior for Windows TCP/IP
http://www.microsoft.com/technet/com...uy/cg0903.mspx

Multiple Default Gateways Can Cause Connectivity Problems
http://support.microsoft.com/kb/159168/EN-US/

--
Mike
Microsoft MVP - Windows Security

"Will" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Can someone help me decipher a routing table and figure out why the
> routing
> is going off course?
>
> We have a Microsoft Proxy Server with internal interface 172.16.20.1 that
> points at internal router 172.16.20.5. External interface is 10.0.0.6
> and
> points to external router 10.0.0.1.
>
> What is happening is that winsock proxy client requests come to the
> Microsoft Proxy Server, and the outbound requests to the Internet are
> being
> redirected to the internal network's router. The internal network router
> does ICMP redirects, and after about 20 seconds, the Microsoft Proxy
> Server
> seems to get the point and then directs the request outbound on the
> correct
> interface.
>
> When the machine first boots the default router in the route print command
> is the external router. Once this problem starts, the route print shows
> the internal router as the default router, even though the metric for the
> internal route is set to 2 and the metric for the external router is 1.
>
> What would cause the machine to start favoring the internal router for
> outgoing Internet requests? Is there a problem in the route table? Do
> we
> need some persistent routes?
>
> --
> Will
>
> Active Routes:
> Network Destination Netmask Gateway Interface
> Metric
> 0.0.0.0 0.0.0.0 10.0.0.1 10.0.0.6 1
> 0.0.0.0 0.0.0.0 172.16.20.5 172.16.20.1 2
> 127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
> 172.16.0.0 255.255.255.0 10.0.0.6 10.0.0.6 1
> 10.0.0.6 255.255.255.255 127.0.0.1 127.0.0.1 1
> 172.16.255.255 255.255.255.255 10.0.0.6 10.0.0.6 1
> 172.16.20.0 255.255.255.0 172.16.20.1 172.16.20.1 2
> 172.16.20.1 255.255.255.255 127.0.0.1 127.0.0.1 2
> 172.16.20.255 255.255.255.255 172.16.20.1 172.16.20.1 2
> 224.0.0.0 224.0.0.0 10.0.0.6 10.0.0.6 1
> 224.0.0.0 224.0.0.0 172.16.20.1 172.16.20.1 2
> 255.255.255.255 255.255.255.255 10.0.0.6 10.0.0.6 1
> Default Gateway: 172.16.20.5
> ================================================== =========================
> Persistent Routes:
> None
>
>