11-24-2022 11:08 AM - edited 11-24-2022 11:13 AM
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
11-24-2022 03:32 PM
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?
11-25-2022 03:47 AM - edited 11-25-2022 03:53 AM
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.
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