Routing Question

From: PC (paulm)
Date: 07/27/04 

Date: Tue, 27 Jul 2004 11:19:43 +0100

Curiosity question this.

I had to install a DSL router/Firewall for a client. They were moving from
their old ISP who was providing domain name hosting and SMTP mail. The
client was using a Cisco 1600 to dialout over ISDN to connect to the
internet and collect mail.

I configured the ADSL router Firewall parallel to the Cisco ISDN router so
the users had access to the internet over ADSL but for a short time the mail
server was still using the ISDN line to collect mail until such time as the
domain move occured.

As part of the job I configured a remote client to use the Firewall VPN
facility to connect to the network over ADSL and this is where the puzzle
started.

The NT Exchange server was configured with a private address
192.168.xxx.xxx. As this server was still collecting mail from the old ISP
the default gateway on the server was still pointing to the Cisco ISDN
Router
One to one Nat was configured on the Cisco to map the private address to the
ISP assigned public address 193.125.xxx.xxx (This has not been changed as
yet to the new ISP)
The remote client would dial out to the internet and the VPN client software
would automatically connect to the ADSL Router/Firewall

BUT when I tried to ping the private IP of the Exchange server (There is
only on server which is running NT4 and Wins. No DNS) from the remote
client, I would get a reply from the Public IP which was configured on the
Cisco 1600 ISDN Router.

i.e.
Ping 192.168.xxx.xxx

Reply from 193.125.xxx.xxx

Why would this happen??

Any routing experts out there?

Relevant Pages

  • Re: Advice needed - running Exchange
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    (microsoft.public.windows.server.sbs)
  • RE: VPNs in SBS2003 using ISA.
    ... Please temporarily place a client directly connected to the external NIC ... Server to a simple hub and connect the client to the same hub. ... we can make sure the issue is caused by the router. ... Microsoft CSS Online Newsgroup Support ...
    (microsoft.public.windows.server.sbs)
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    (microsoft.public.windows.server.sbs)