Destination NAT configuration example

R1 :-

interface FastEthernet0/0

 description " Connected to R2 "

 ip address 12.12.12.1 255.255.255.0

 no shut

interface FastEthernet2/0

description " Connected to PC1 "

 ip address 10.1.1.1 255.255.255.0

no shut

router bgp 1

 no synchronization

 bgp log-neighbor-changes

 network 10.1.1.0 mask 255.255.255.0

 neighbor 12.12.12.2 remote-as 2

 no auto-summary

ip route 143.20.1.0 255.255.255.0 12.12.12.2

R2 :-

interface FastEthernet0/0

 description " Connected to R1 "

 ip address 12.12.12.2 255.255.255.0

 ip nat inside

 no shut

interface FastEthernet0/1

 description " Connected to R3 "

 ip address 23.23.23.2 255.255.255.0

 ip nat outside

 no shut

router bgp 2

 no synchronization

 bgp log-neighbor-changes

 network 143.20.1.0 mask 255.255.255.0

 neighbor 12.12.12.1 remote-as 1

 neighbor 23.23.23.3 remote-as 3

 no auto-summary

ip nat pool Pulic_pool_143.20.1.x 143.20.1.1 143.20.1.255 netmask 255.255.255.0 type match-host

ip nat outside source list R3_Subnets pool Pulic_pool_143.20.1.x

ip access-list standard R3_Subnets

 permit 20.1.1.0 0.0.0.255

ip route 143.20.1.0 255.255.255.0 23.23.23.3

R3 :-

interface FastEthernet0/1

 description " Connected to R2 "

 ip address 23.23.23.3 255.255.255.0

 no shut

interface FastEthernet2/0

 description " Connected to PC2 "

 ip address 20.1.1.1 255.255.255.0

no shut

router bgp 3

 no synchronization

 bgp log-neighbor-changes

 neighbor 23.23.23.2 remote-as 2

 no auto-summary

PC1:-

PC1> show ip

NAME        : PC1[1]

IP/MASK     : 10.1.1.10/24

GATEWAY     : 10.1.1.1

DNS         :

MAC         : 00:50:79:66:68:00

LPORT       : 10007

RHOST:PORT  : 127.0.0.1:10006

MTU:        : 1500

PC2:-

PC2> sh ip

NAME        : PC2[1]

IP/MASK     : 20.1.1.10/24

GATEWAY     : 20.1.1.1

DNS         :

MAC         : 00:50:79:66:68:01

LPORT       : 10001

RHOST:PORT  : 127.0.0.1:10000

MTU:        : 1500

Verification:-

R1:-

R1#sh ip route

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route, H - NHRP

       + - replicated route, % - next hop override

Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        10.1.1.0/24 is directly connected, FastEthernet2/0

L        10.1.1.1/32 is directly connected, FastEthernet2/0

      12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        12.12.12.0/24 is directly connected, FastEthernet0/0

L        12.12.12.1/32 is directly connected, FastEthernet0/0

      143.20.0.0/24 is subnetted, 1 subnets

S        143.20.1.0 [1/0] via 12.12.12.2

      143.30.0.0/24 is subnetted, 1 subnets

S        143.30.1.0 [1/0] via 12.12.12.2

R1#sh ip bgp summ

BGP router identifier 12.12.12.1, local AS number 1

BGP table version is 15, main routing table version 15

2 network entries using 256 bytes of memory

2 path entries using 104 bytes of memory

2/2 BGP path/bestpath attribute entries using 248 bytes of memory

1 BGP AS-PATH entries using 24 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 632 total bytes of memory

BGP activity 6/4 prefixes, 7/5 paths, scan interval 60 secs

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd

12.12.12.2      4            2     183     179       15    0    0 02:38:24        1

R2:-

R2#sh ip nat translations

Pro Inside global      Inside local       Outside local      Outside global

--- ---                ---                                     143.20.1.10        20.1.1.10   --<<< Destination NAT

icmp 10.1.1.10:57480   10.1.1.10:57480    143.20.1.10:57480  20.1.1.10:57480

icmp 10.1.1.10:57992   10.1.1.10:57992    143.20.1.10:57992  20.1.1.10:57992

icmp 10.1.1.10:58504   10.1.1.10:58504    143.20.1.10:58504  20.1.1.10:58504

icmp 10.1.1.10:58760   10.1.1.10:58760    143.20.1.10:58760  20.1.1.10:58760

icmp 10.1.1.10:59016   10.1.1.10:59016    143.20.1.10:59016  20.1.1.10:59016

icmp 10.1.1.10:59272   10.1.1.10:59272    143.20.1.10:59272  20.1.1.10:59272

R2#sh ip nat translations

Pro Inside global      Inside local       Outside local      Outside global

--- ---                ---                143.20.1.10        20.1.1.10

icmp 10.1.1.10:8074    10.1.1.10:8074     143.20.1.10:8074   20.1.1.10:8074

R2#sh ip nat translations verbose

Pro Inside global      Inside local       Outside local      Outside global

--- ---                ---                143.20.1.10        20.1.1.10

    create 00:06:23, use 00:01:03, left 23:58:56, Map-Id (Out): 1,

    flags:

outside, use_count: 0, entry-id: 558, lc_entries: 0

R3:-

R3#sh ip bgp summary

BGP router identifier 23.23.23.3, local AS number 3

BGP table version is 13, main routing table version 13

2 network entries using 256 bytes of memory

2 path entries using 104 bytes of memory

2/2 BGP path/bestpath attribute entries using 248 bytes of memory

2 BGP AS-PATH entries using 48 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 656 total bytes of memory

BGP activity 6/4 prefixes, 7/5 paths, scan interval 60 secs

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd

23.23.23.2      4            2     170     165       13    0    0 02:26:36        2

R3#sh ip route

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route, H - NHRP

       + - replicated route, % - next hop override

Gateway of last resort is not set

      10.0.0.0/24 is subnetted, 1 subnets

B        10.1.1.0 [20/0] via 23.23.23.2, 02:09:41

      20.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        20.1.1.0/24 is directly connected, FastEthernet2/0

L        20.1.1.1/32 is directly connected, FastEthernet2/0

      23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        23.23.23.0/24 is directly connected, FastEthernet0/1

L        23.23.23.3/32 is directly connected, FastEthernet0/1

      143.20.0.0/24 is subnetted, 1 subnets

B        143.20.1.0 [20/0] via 23.23.23.2, 02:07:49

R3#

PC1:-

PC1> ping 143.20.1.10

84 bytes from 143.20.1.10 icmp_seq=1 ttl=61 time=78.000 ms

84 bytes from 143.20.1.10 icmp_seq=2 ttl=61 time=78.000 ms

84 bytes from 143.20.1.10 icmp_seq=3 ttl=61 time=62.400 ms

84 bytes from 143.20.1.10 icmp_seq=4 ttl=61 time=93.600 ms

84 bytes from 143.20.1.10 icmp_seq=5 ttl=61 time=93.600 ms

PC2:-

PC2> ping 10.1.1.10 -t

84 bytes from 10.1.1.10 icmp_seq=3 ttl=61 time=46.800 ms

84 bytes from 10.1.1.10 icmp_seq=4 ttl=61 time=78.000 ms

84 bytes from 10.1.1.10 icmp_seq=5 ttl=61 time=62.400 ms

84 bytes from 10.1.1.10 icmp_seq=6 ttl=61 time=78.000 ms

84 bytes from 10.1.1.10 icmp_seq=7 ttl=61 time=93.600 ms