Example 3: Changing The Source Ip Address Of Wan Traffic - Nortel BCM 3.7 Manual

Example 3: Changing the source IP address of WAN traffic

A Business Communications Manager has a WAN and two LANs. The WAN1 interface connects
to the outside and has an IP address of 192.168.12.90. The Business Communications Manager
also has an ISDN WAN backup interface that gets it IP address dynamically. The LAN1 interface
connects to the LAN and has an IP address of 10.0.84.50. The LAN2 interface has no connections
and has an IP address of 10.255.5.86.
The customer has a management PC on the WAN. This management PC has a firewall filter that
allows traffic only from the LAN2 interface IP address. The customer wants the Business
Communications Manager to send SNMP traps and Call Detail Recording data (FTP transfer) over
the WAN interface to the management PC. To get past the firewall, the data packets must have the
LAN2 interface IP address. The following six NAT rules will change the IP address of SNMP,
SNMP Trap and Call Detail Recording data packets to the IP address of the LAN2 interface.
The three rules required on the WAN interface are:
Rule name R1
Direction Out
Protocol TCP/UDP
Private IP Type Fixed
Private IP 192.168.12.90
Private Range Mask 255.255.255.255
Private Port Range SNMP
Public IP Type Fixed
Public IP 10.255.5.86
Public Range Mask 255.255.255.255
Public Port Range SNMP
Rule name R2
Direction Out
Protocol TCP/UDP
Private IP Type Fixed
Private IP 192.168.12.90
Private Range Mask 255.255.255.255
Private Port Range SNMPTRAP
Public IP Type Fixed
Public IP 10.255.5.86
Public Rang Mask 255.255.255.255
Public Port Range SNMPTRAP
Configuring an Interface with NAT
Programming Operations Guide
745