Static NAT on one ISP with default route on different ISP

Unanswered Question
Nov 12th, 2009
User Badges:

We have one router with connections to two different ISPs. Static NATs are configured to servers using IPs from ISP A. The customer is migrating everything eventually to ISP B. At this moment, we want to make all outbound traffic flow through ISP B but keep the static NATs to the servers on ISP A.

default route - ISP B

server 1 static NAT ISP A

server 2 static NAT ISP A

server 3 static NAT ISP A

The problem is that once ISP B is the default route, the static NATs break. How do we get traffic meant for the servers that comes in ISP A to return through ISP A?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Jon Marshall Thu, 11/12/2009 - 09:14
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN


You can use PBR for this ie. traffic with a source address of one of the servers is sent to the ISP A next hop eg.

access-list 101 permit ip host any

access-list 101 permit ip host any

access-list 101 permit ip host any

note the server addresses would need to be the real address ie. not the natted ones.

route-map PBR permit 10

match ip address 101

set ip next-hop

then on the LAN interface of your router

int fa0/0

ip policy route-map PBR



This Discussion