Hello Gregory,
 thanks for your answer, Static NAT may work but I want to simulate the NAT
inside the core network where I don't have a control.

You are right in saying GNS3 it is not like the real equipment. However the
Cisco documentation regarding DMVPN behind nat it is not clear at all.
there are a lot of "may ".

Also the scenario the put as example is just a spoke behind NAT. That
scenario works correctly in GNS3.

http://www.cisco.com/c/en/us/td/docs/ios/sec_secure_connectivity/configuration/guide/15_0/sec_secure_connectivity_15_0_book/dmvpn_dt_spokes_b_nat.html


So I've just the suspect something is wrong.

Thanks
Cristiano




2014-02-21 11:47 GMT+00:00 Gregory Volcy <[email protected]>:

> Change your nat from pat to static.  Also remember gns3 is not real
> equipment you have other issues other then cisco dmvpn config that my case
> that issue. My be your chasing a ghost.
> On Feb 21, 2014 6:31 AM, "Cristiano Guerrieri" <[email protected]> wrote:
>
>> Hi all,
>>  I'm running a bit of tests using GNS3. I built several scenarios using
>> DMVPN. There is one in particular that is driving me crazy .
>>
>>
>> Basically I have two spokes behind the same NAT router and the HUB is
>> facing the NAT router. NAT router and HUB are onto the same network.
>>
>> The problem I'm running into is I have only a spoke working (able to ping
>> the hub) at time, even though, under the "sh dmvpn" I can see both spokes
>> correctly registered. The working spoke however has intermittent
>> connection
>> toward the hub.
>>
>> Interface: Tunnel0, IPv4 NHRP Details
>> Type:Hub, Total NBMA Peers (v4/v6): 2
>>
>> # Ent  Peer NBMA Addr Peer Tunnel Add State  UpDn Tm Attrb    Target
>> Network
>> ----- --------------- --------------- ----- -------- -----
>> -----------------
>>     1        0.0.0.0         1.1.1.1  NHRP    never   IX
>> 1.1.1.1/32
>>
>>     2     172.16.1.2         1.1.1.2    UP 00:00:20   DN
>> 1.1.1.2/32
>>        Claimed Addr. 10.2.2.2
>>     0     172.16.1.2         1.1.1.3    UP 00:00:34   DN
>> 1.1.1.3/32
>>        Claimed Addr. 10.2.2.3
>>
>>
>> HUB-1#sh ip nhrp detail
>> 1.1.1.2/32 via 1.1.1.2
>>    Tunnel0 created 00:12:11, expire 01:47:48
>>    Type: dynamic, Flags: unique registered
>>     NBMA address: 172.16.1.2
>>     (Claimed NBMA address: 10.2.2.2)
>> 1.1.1.3/32 via 1.1.1.3
>>    Tunnel0 created 00:12:25, expire 01:50:47
>>    Type: dynamic, Flags: unique registered
>>    NBMA address: 172.16.1.2
>>     (Claimed NBMA address: 10.2.2.3)
>>
>>
>>
>> Below the ping form spoke 1
>>
>> Type escape sequence to abort.
>> Sending 1000, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
>> !!!!.!.!!!!!!!.!.!!!!!!!!!!!!!!!!!!!!!!.!.!!!!!!!!!!!!!!!!!!!!!!.!.!!!
>> !!!!!!!!!!!!!!!!!!!
>> *Mar  1 00:03:38.131: %CRYPTO-4-RECVD_PKT_MAC_ERR: decrypt: mac verify
>> failed for connection
>> id=1.!.!!!!!!!!!!!!!!!!!!!!!!!!!.!.!!!!!!!!!!!!!!!!!!!!
>> !!!!!.!!!!!!!!!!!!!!!.!!!!!!!!.!!!!!!!!!!!!!!!.!!!!!!!!.!!!!!!!!!!!!!!
>> !.!!!!!!!!!!!!!.!.!!!!!!!!!!!!!!!!!!!!!!.!.!!!!!!!!!!!!!!!!!!!!!!!!!!!
>> !!!!!!!.!!!!.!!!!!!!!!!!!!!!!!!!
>>
>>
>> I've noticed that %CRYPTO-4-RECVD_PKT_MAC_ERR. Looking at the Cisco
>> documentation looks like the packet is corrupted or there is a problem
>> with
>> the link.
>>
>> Pinging from both spokes at the same time when Spoke-1 works spoke-2
>> cannot
>> ping the hub and viceversa. This moves from one to the other randomly.
>>
>>
>> Below the relevant configs
>>
>> HUB-1#sh run | sec crypto
>> crypto isakmp policy 10
>>  encr aes
>>  authentication pre-share
>> crypto isakmp key test address 0.0.0.0 0.0.0.0
>> crypto ipsec transform-set trans-dmvpn esp-3des esp-sha-hmac
>>  mode transport
>> crypto ipsec profile DMVPN
>>  set transform-set trans-dmvpn
>> HUB-1#sh run inter tunnel 0
>> Building configuration...
>>
>> Current configuration : 296 bytes
>> !
>> interface Tunnel0
>>  ip address 1.1.1.1 255.255.255.0
>>  no ip redirects
>>  ip nhrp authentication test
>>  ip nhrp map multicast dynamic
>>  ip nhrp network-id 1
>>  ip ospf network point-to-multipoint
>>  tunnel source FastEthernet0/0
>>  tunnel mode gre multipoint
>>  tunnel protection ipsec profile DMVPN
>>  !
>>  end
>>
>> Current configuration : 98 bytes
>> !
>> interface FastEthernet0/0
>>  ip address 172.16.1.1 255.255.255.0
>>  duplex auto
>>  speed auto
>>  !
>> end
>> HUB-1#sh run inter fas 0/1
>> Building configuration...
>>
>> Current configuration : 101 bytes
>> !
>> interface FastEthernet0/1
>>  ip address 192.168.200.1 255.255.255.0
>>  duplex auto
>>  speed auto
>>  !
>> ----------------------------------------
>>
>> Spoke-1#sh run | s crypto
>> crypto isakmp policy 10
>>  encr aes
>>  authentication pre-share
>> crypto isakmp key test address 0.0.0.0 0.0.0.0
>> crypto ipsec transform-set trans esp-3des esp-sha-hmac
>>  mode transport
>> crypto ipsec profile DMVPN
>>  set transform-set trans
>>
>> Building configuration...
>>
>> Current configuration : 380 bytes
>> !
>> interface Tunnel0
>>  ip address 1.1.1.2 255.255.255.0
>>  no ip redirects
>>  ip nhrp authentication test
>>  ip nhrp map multicast dynamic
>>  ip nhrp map 1.1.1.1 172.16.1.1
>>  ip nhrp map multicast 172.16.1.1
>>  ip nhrp network-id 1
>>  ip nhrp nhs 1.1.1.1
>>  ip ospf network point-to-multipoint
>>  tunnel source FastEthernet0/0
>>  tunnel mode gre multipoint
>>  tunnel protection ipsec profile DMVPN
>> end
>>
>>
>> Spoke-1#sh run int fas 0/0
>> Building configuration...
>>
>> Current configuration : 92 bytes
>> !
>> interface FastEthernet0/0
>>  ip address 10.2.2.2 255.255.255.0
>>  speed 100
>>  full-duplex
>> end
>>
>> Spoke-1#sh run int fas 0/1
>> Building configuration...
>>
>> Current configuration : 92 bytes
>> !
>> interface FastEthernet0/1
>>  ip address 10.1.1.1 255.255.255.0
>>  speed 100
>>  full-duplex
>>
>>
>>
>> ---------------------------------------
>>
>> Spoke-2#sh run | s crypto
>> crypto isakmp policy 10
>>  encr aes
>>  authentication pre-share
>> crypto isakmp key test address 0.0.0.0 0.0.0.0
>> crypto ipsec transform-set trans esp-3des esp-sha-hmac
>>  mode transport
>> crypto ipsec profile DMVPN
>>  set transform-set trans
>> Spoke-2#
>>
>> Spoke-2#sh run int tun 0
>> Building configuration...
>>
>> Current configuration : 380 bytes
>> !
>> interface Tunnel0
>>  ip address 1.1.1.3 255.255.255.0
>>  no ip redirects
>>  ip nhrp authentication test
>>  ip nhrp map multicast dynamic
>>  ip nhrp map 1.1.1.1 172.16.1.1
>>  ip nhrp map multicast 172.16.1.1
>>  ip nhrp network-id 1
>>  ip nhrp nhs 1.1.1.1
>>  ip ospf network point-to-multipoint
>>  tunnel source FastEthernet0/0
>>  tunnel mode gre multipoint
>>  tunnel protection ipsec profile DMVPN
>> end
>>
>>
>> Spoke-2#sh run in fas 0/0
>> Building configuration...
>>
>> Current configuration : 92 bytes
>> !
>> interface FastEthernet0/0
>>  ip address 10.2.2.3 255.255.255.0
>>  speed 100
>>  full-duplex
>> end
>>
>> Spoke-2#sh run in fas 0/1
>> Building configuration...
>>
>> Current configuration : 94 bytes
>> !
>> interface FastEthernet0/1
>>  ip address 172.31.1.1 255.255.255.0
>>  speed 100
>>  full-duplex
>> end
>>
>> ---------------------------------
>>
>> NAT-1#sh run int fas 0/0
>> Building configuration...
>>
>> Current configuration : 133 bytes
>> !
>> interface FastEthernet0/0
>>  ip address 172.16.1.2 255.255.255.0
>>  ip nat outside
>>  ip virtual-reassembly
>>  speed 100
>>  full-duplex
>> end
>>
>> NAT-1#sh run int fas 0/1
>> Building configuration...
>>
>> Current configuration : 130 bytes
>> !
>> interface FastEthernet0/1
>>  ip address 10.2.2.1 255.255.255.0
>>  ip nat inside
>>  ip virtual-reassembly
>>  speed 100
>>  full-duplex
>> end
>>
>> NAT-1#sh run | i nat
>>  ip nat outside
>>  ip nat inside
>> ip nat inside source list 1 interface FastEthernet0/0 overload
>> NAT-1#
>>
>>
>>
>>
>>
>> Any Ideas or suggestions?
>>
>> Thanks,
>> Cristiano
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>
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