explain nat and routes

rajbhatt · ‎04-28-2007

Hi ,

Heres my scenerio:

Server A is conencted to router 3 also

router3

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sw1---serverA 192.168.1.1

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router1 Here there are 2 route maps and relevant routes to router2 and also to outside

|

Sw2

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router2 ip nat inside source static 192.168.1.1 10.1.1.1 and specific routes

|

sw3

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serverB 10.2.2.2

My question is traffic should go from server B to server A.

On router1

ip nat inside source route-map x pool x-Server

ip access-list extended x

permit ip any host 192.168.1.1

ip nat pool x-Server 40.40.1.2 40.40.1.3 netmask 255.255.252.0

route-map x Map permit 10

match ip address x

route 10.0.0.0 255.255.255.0 router2

On router 2

A.route 192.168.1.0 255.255.255.0 router1

B.route 10.1.1.0 255.255.255.0 router 1

ip nat inside source static 192.168.1.1 10.1.1.1

My questions is

1.So when checking the routes to go from server b to server A should it check route A or B and what will be the nat

2.What should be the route it will check and nat translation it will check for the return packet

Thanks in advance

Raj

royalblues · ‎04-28-2007

what is the inside and outside interafces of the routers R1 and r2

Narayan

rajbhatt · ‎04-29-2007

hi,

AS u can see from the figure r1 connects to a switch on the outside and on the inside it is conencted to a firewall

R2 is conencted to a inside of firewall and is conencted to internal networks via 2 swicthes

I just wanted to find out how the ip source natting is happening and how does it use the route table

Thanks

Raj

rajbhatt · ‎04-29-2007

Hi

If server B requests info from server A :

192.168.1.1 should be converted to 10.1.1.1.

It should check the route route 10.1.1.0 255.255.255.0 router 1

or should it check the route :route 192.168.1.0 255.255.255.0 router1

Because as far as i know first it ckecks route and then proceeds to translate .

My confusion here is

what should be the translation

Once it reaches router 1 it hits the router map :it takes address of 40.40 and access server

ip nat pool x-Server 40.40.1.2 40.40.1.3 netmask 255.255.252.0

route-map x Map permit 10

match ip address x

Traffic reaches server A

While the packet will come back :

It will just check the nat in router 1 and foward the packet based on route

route 10.0.0.0 255.255.255.0 router2

Am I correct in my assumption ?Please clarify if I am wrong

I cannot understand the persence of this route ?

Thanks in advance

Raj