Hi Fernando,
You can do this enabling ACL's on the CSS and making them NAT only the specific traffic that you need:
I just pasted a config sample below, basically you'll need:
1) A source group with the specific IP you want to use for NAT, this sourcegroup will not have any services configured either as add service nor add destination service.
2) A network qualifier list (NQL) where you will add the internal hosts that require NAT
3) Finally create an ACL where you specify the NQL as the source of the request to the specific destination IP and the sourcegroup to NAT the request. Please note that at the end there's an IP any any so that all the traffic that is not matched by the first lines is routed/load balanced normally through the CSS.
* You need to create/apply an ACL per circuit on the CSS, even if that interface is just for redundancy.
group Outbound-NAT
vip address 172.16.4.100
active
nql Internal-Hosts
ip address 172.16.4.9 255.255.255.255
ip address 172.16.4.10 255.255.255.255
acl 1
clause 10 permit any nql Internal-Hosts destination 50.50.50.50 255.255.255.255 sourcegroup Outbound-NAT
clause 11 permit any nql Internal-Hosts destination 60.60.60.60 255.255.255.255 sourcegroup Outbound-NAT
clause 12 permit any nql Internal-Hosts destination 70.70.70.70 255.255.255.255 sourcegroup Outbound-NAT
clause 13 permit any nql Internal-Hosts destination 80.70.80.80 255.255.255.255 sourcegroup Outbound-NAT
clause 30 permit any any destination any
apply circuit-(VLANX)
CSS(config)# acl enable
HTH
__ __
Pablo
