Return traffic by other ISP

[hcalderon]

Hello people  

 I have an implementation:

Problem:
One router + 2 isp --->  traffic arriving from internet I have  to nat and if  fail I have to route evething for the other isp

Solucion:

 Two default  routes with diferent metric and  Track  SLA , so in this  way all return trafico  from internet  (ISP 1) is  gonna out ( return) for the other  ISP ( ISP2)

But  what  happend if some  particular trafic coming ( internet) by isp 1 change  to isp 2 ( from outside always) how can I return that  trafic for the isp 2 ( backup link)

***Al the  trafic coming   from internet  ( source ) is not  identificated: is any.

So, the problem is  not if link by ISP 1 fail, the problem is ¿what can I do if some particular traffic o service from internet want to reach me by isp2 and how can i  return that specific  traffic by the same isp 2 

[balaji.bandi]

Are you running BGP with ISP, if asymmetric not going to work for you? Since other ISP2s are not aware of ISP 1 IP address and router via ISP2 network( if you have own IP address space and running ebgp with ISP)

when you do static route or PBR  with IP sla - you can have active/active(split load) or active standby fail over.

So traffic leaving from ISP will be NAtter with ISP 1 Public IP so the return traffic will return from same link

When ISP1 fails, the Routing and NAT change towards ISP2 so return traffic will from ISP2 only?

[MHM Cisco World]

what you need here what we called conditional NAT 

ip nat inside source static x.x.x.x route-map MHM interface 
!
route-map MHM permit 10
match interface <ISP1>

this way the NAT is depend on which interface is used for traffic.