explain nat and routes

Unanswered Question
Apr 28th, 2007
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Hi ,

Heres my scenerio:

Server A is conencted to router 3 also


router3

| ||

sw1---serverA 192.168.1.1

|

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

|

Sw2

|

router2 ip nat inside source static 192.168.1.1 10.1.1.1 and specific routes

|

sw3

|

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


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royalblues Sat, 04/28/2007 - 08:33
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what is the inside and outside interafces of the routers R1 and r2


Narayan

rajbhatt Sun, 04/29/2007 - 21:18
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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 Sun, 04/29/2007 - 22:58
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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

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