Solved: Natting problem

pcromwell · ‎04-29-2017

Hi I have a L3 switch stack with SVI vlans ( approx 5 vlan) the uplinks are L3 ports with Ip addresses assigned and running Ospf going to 2 routers for redundancy the routers have L3 ports only. All the vlans on the switch need to get Internet access some are static nat and some will need dynamic.

My Public ip range is say 100.100.100.0 my BGP uplinks from this router use a carrier provided transit network with a /31 mask

have attached a layout of the design. On the routers I have tried to configure static nat and also dynamic with an ACL. but when I debug nat nothing happens.

I am not sure where I need to put my ip nat inside statement as the incoming traffic from the switch to the router are L3 interface and are a different subnet range from any of the svis on the switch. I guess I might need to make the links from routers to switches as subinterfaces?

If I did would that not impact the redundancy I am looking for?

Jon Marshall · ‎04-29-2017

You just configure "ip nat inside" on the router interface(s) that connects to the switch(es). There is no requirement for the interface(s) to be in the same IP subnet(s) as the IPs you are doing NAT for.

Presumably you have routing between the switches and routers all working ?

If so can perhaps you can post the NAT configuration you are using.

Jon

View solution in original post

Jon Marshall · ‎04-29-2017

You just configure "ip nat inside" on the router interface(s) that connects to the switch(es). There is no requirement for the interface(s) to be in the same IP subnet(s) as the IPs you are doing NAT for.

Presumably you have routing between the switches and routers all working ?

If so can perhaps you can post the NAT configuration you are using.

Jon

pcromwell · ‎04-29-2017

many thanks Jon, that worked perfectly. It makes sense now.