3Com OfficeConnect 3C840 Installation and operating instructions

Static NAT and Dynamic NAT Usage for 2 WEB
Servers and Workstations for Internet Access
Using OCR840 SDSL Router.
This Application note will detail the methodology and configuration of Remote offices having Multiple
Web Servers with the Regular Internet Browser Users connecting to a central Office DSLAM site using
Static and Dynamic NAT Technology.

Remote Office OCR840 Setup: -
Power up an OCR840 SDSL Router and Connect the PC’s as shown…
1) WEB Server 1 with Static IP address of 140.179.1.2/c
2) WEB Server 2 with Static IP address of 140.179.1.3/c
3) Workstation 3 with Static IP address of 140.179.1.4/c
4) Workstation 4 with Static IP address of 140.179.1.5/c
And Configure the OCR840 SDSL Router with an IP address of 140.179.1.1/c as below…
ADD IP NET ip ADDR 140.179.1.1/C INTERFACE eth:1 FRAME ETHERNET_II
ENABLE IP FORWARDING
ENABLE IP WAN_TO_WAN_FORWARDING
ADD VC e
SET VC e BRIDGING DISABLE DEFAULT_ROUTE_OPTION ENABLE DLCI 16
SET VC e IP ENABLE IPX DISABLE
SET VC e LOCAL_IP_ADDRESS 11.1.1.2 MAC_ROUTINGENABLE NAT_OPTION NAT
SET VC e NETWORK_SERVICE RFC_1490 OUTPUT_FILTER "" REMOTE_IP_ADDRESS 11.1.1.1
ADD NAT STATIC VC e PUBLIC_ADDR 12.1.1.1 PRIVATE_ADDR 140.179.1.2
ADD NAT STATIC VC e PUBLIC_ADDR 12.1.1.2 PRIVATE_ADDR 140.179.1.3
ADD NAT DYNAMIC VC e PUBLIC_POOL_START 12.1.1.3 COUNT 5
ENABLE VC e
Note the above 12.1.1.0 is a Public IP address Subnet given to the Customer. I have Used 3 Public Address
and have mapped
1) 12.1.1.1 Public IP address Mapped in the OCR840 Static NAT Table to the IP address of 140.179.1.2/c
of WEB Server 1.
2) 12.1.1.2 Public IP address Mapped in the OCR840 Static NAT Table to the IP address of 140.179.1.3/c
of WEB Server 2.
3) 12.1.1.3 Public IP address Mapped in the OCR840 Dynamic NAT Table to the IP Subnet of the
Workstations with the Maximum Stations of 5.
Also Note the Local IP address 11.1.1.2/c and Remote DSLAM WAN Address 11.1.1.1/c are just for the
WAN Link Identification.
Central Office DSLAM / PC Setup: -
The DSLAM is configured with an IP address of 192.168.1.1/c with the PC’s in the LAN configured for the
same Subnet.
Configure the DSLAM for the OCR840 connectivity with a WAN IP address of 11.1.1.1/c and Put in an IP
Route with Destination of the Public IP address 12.1.1.0 via NEXT HOP 11.1.1.2/c.
Now the PC’s onthe DSLAM can Ping/access each webserver using the Static Defined Public IP address
and the Workstations on the OCR840 can access the Internet using the Dynamic Public IP address.