Stateful NAT (SNAT)

Posted on April 8, 2011. Filed under: cisco ios | Tags: nat, snat |

Nice feature for maintaining stateful NAT sessions between two border routers.

Communication is established between two or more routers via TCP, session information is shared.

ISP2#sh ip snat distributed
Stateful NAT Connected Peers
SNAT: Mode BACKUP    : State READY    : Local Address 10.0.0.3    : Local NAT id 2    : Peer Address 10.0.0.2    : Peer NAT id 1    : Mapping List 10

ISP2#sh ip snat peer 10.0.0.2
Show NAT Entries created by peer: 10.0.0.2
Pro Inside global      Inside local       Outside local      Outside globalicmp 10.0.0.15:2       192.168.1.254:2    10.0.0.1:2         10.0.0.1:2

!
ip nat Stateful id 1
primary 10.0.0.2
peer 10.0.0.3
mapping-id 10
ip nat pool nat-pool 10.0.0.15 10.0.0.20 netmask 255.255.255.0
ip nat inside source route-map nat-rm pool nat-pool mapping-id 10 overload