Invalid Security Parameter Index Recovery

When an invalid security parameter index error (shown as “Invalid SPI”) occurs in IP Security (IPsec) packet processing, the Invalid Security Parameter Index Recovery feature allows for an Internet Key Exchange (IKE) security association (SA) to be established. The “IKE” module sends notification of the “Invalid SPI” error to the originating IPsec peer so that Security Association Databases (SADBs) can be resynchronized and successful packet processing can be resumed.


Note

Security threats, as well as the cryptographic technologies to help protect against them, are constantly changing. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for Invalid Security Parameter Index Recovery

Before configuring the Invalid Security Parameter Index Recovery feature, you must have enabled Internet Key Exchange (IKE) and IPsec on your router.

Restrictions for Invalid Security Parameter Index Recovery

If an IKE SA is being initiated to notify an IPsec peer of an “Invalid SPI” error, there is the risk that a denial-of-service (DoS) attack can occur. The Invalid Security Parameter Index Recovery feature has a built-in mechanism to minimize such a risk, but because there is a risk, the Invalid Security Parameter Index Recovery feature is not enabled by default. You must enable the command using command-line interface (CLI).

Information About Invalid Security Parameter Index Recovery

How the Invalid Security Parameter Index Recovery Feature Works

An IPsec “black hole” occurs when one IPsec peer “dies” (for example, a peer can “die” if a reboot occurs or if an IPsec peer somehow gets reset). Because one of the peers (the receiving peer) is completely reset, it loses its IKE SA with the other peer. Generally, when an IPsec peer receives a packet for which it cannot find an SA, it tries to send an IKE “INVALID SPI NOTIFY” message to the data originator. This notification is sent using the IKE SA. If there is no IKE SA available, the receiving peer drops the packet.


Note

A single security association (SA) has only two peers. However, a SADB can have multiple SAs, whereby each SA has an association with a different peer.

When an invalid security parameter index (SPI) is encountered, the Invalid Security Parameter Index feature provides for the setting up of an IKE SA with the originator of the data, and the IKE “INVALID SPI NOTIFY” message is sent. The peer that originated the data “sees” the “INVALID SPI NOTIFY” message and deletes the IPsec SA that has the invalid SPI. If there is further traffic from the originating peer, there will not be any IPsec SAs, and new SAs will be set up. Traffic will flow again. The default behavior (that is, without configuring the Invalid Security Parameter Index Recovery feature) is that the data packet that caused the invalid SPI error is dropped. The originating peer keeps on sending the data using the IPsec SA that has the invalid SPI, and the receiving peer keeps dropping the traffic (thus creating the “black hole”).

The IPsec module uses the IKE module to send an IKE “INVALID SPI NOTIFY” message to the other peer. Once the invalid SPI recovery is in place, there should not be any significant dropping of packets although the IPsec SA setup can itself result in the dropping of a few packets.

To configure your router for the Invalid Security Parameter Index Recovery feature, use the crypto isakmp invalid-spi-recovery command. The IKE SA will not be initiated unless you have configured this command.

How to Configure Invalid Security Parameter Index Recovery

Configuring Invalid Security Parameter Index Recovery

To configure the Invalid Security Parameter Index Recovery feature, perform the following steps.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    crypto isakmp invalid-spi-recovery


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Router> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example:
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 3 crypto isakmp invalid-spi-recovery


    Example:
    Router (config)# crypto isakmp invalid-spi-recovery
     

    Initiates the IKE module process whereby the IKE module notifies the receiving peer that an “Invalid SPI” error has occurred.

     

    Verifying the Invalid Security Parameter Index Recovery Configuration

    To determine the status of the IPsec SA for traffic between two peers, you can use the show crypto ipsec sa command. If the IPsec SA is available on one peer and not on the other, there is a “black hole” situation, in which case you will see the invalid SPI errors being logged for the receiving peer. If you turn console logging on or check the syslog server, you will see that these errors are also being logged.

    The figure below shows the topology of a typical preshared configuration setup. Host 1 is the initiating peer (initiator), and Host 2 is the receiving peer (responder).

    Figure 1. Preshared Configuration Topology

    SUMMARY STEPS

      1.    Initiate the IKE and IPsec SAs between Host 1 and Host 2

      2.    Clear the IKE and IPsec SAs on Router B

      3.    Send traffic from Host 1 to Host 2 and ensure that new IKE and IPsec SAs are correctly established


    DETAILED STEPS
      Step 1   Initiate the IKE and IPsec SAs between Host 1 and Host 2

      Router A



      Example:
      Router# show crypto isakmp sa
  f_vrf/i_vrf   dst            src             state       conn-id slot 
       / 10.2.2.2              10.1.1.1        QM_IDLE               1       0

      Router B



      Example:
      Router# show crypto isakmp sa
  f_vrf/i_vrf   dst            src             state       conn-id slot 
       /        10.1.1.1       10.2.2.2        QM_IDLE               1       0

      Router A



      Example:
      Router# show crypto ipsec sa interface fastethernet0/0
interface: FastEthernet0/0 
    Crypto map tag: testtag1, local addr. 10.1.1.1
   protected vrf: 
   local  ident (addr/mask/prot/port): (10.0.0.1/255.255.255.255/0/0) 
   remote ident (addr/mask/prot/port): (10.0.2.2/255.255.255.255/0/0) 
   current_peer: 10.2.2.2:500 
     PERMIT, flags={origin_is_acl,} 
    #pkts encaps: 10, #pkts encrypt: 10, #pkts digest: 10 
    #pkts decaps: 10, #pkts decrypt: 10, #pkts verify: 10 
    #pkts compressed: 0, #pkts decompressed: 0 
    #pkts not compressed: 0, #pkts compr. failed: 0 
    #pkts not decompressed: 0, #pkts decompress failed: 0 
    #send errors 0, #recv errors 0 
     local crypto endpt.: 10.1.1.1, remote crypto endpt.: 10.2.2.2 
     path mtu 1500, media mtu 1500 
     current outbound spi: 7AA69CB7 
     inbound esp sas: 
      spi: 0x249C5062(614223970) 
        transform: esp-aes esp-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5123, flow_id: 1, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4537831/3595) 
        IV size: 16 bytes 
        replay detection support: Y 
     inbound ah sas: 
      spi: 0xB16D1587(2976716167) 
        transform: ah-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5121, flow_id: 1, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4537831/3595) 
        replay detection support: Y 
     inbound pcp sas: 
     outbound esp sas: 
      spi: 0x7AA69CB7(2057739447) 
        transform: esp-aes esp-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5124, flow_id: 2, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4537835/3595) 
        IV size: 16 bytes 
        replay detection support: Y 
     outbound ah sas: 
      spi: 0x1214F0D(18960141) 
        transform: ah-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5122, flow_id: 2, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4537835/3594) 
        replay detection support: Y 
     outbound pcp sas:

      Router B



      Example:
      Router# show crypto ipsec sa interface ethernet1/0
interface: Ethernet1/0 
    Crypto map tag: testtag1, local addr. 10.2.2.2 
   protected vrf: 
   local  ident (addr/mask/prot/port): (10.0.2.2/255.255.255.255/0/0) 
   remote ident (addr/mask/prot/port): (10.0.0.1/255.255.255.255/0/0) 
   current_peer: 10.1.1.1:500 
     PERMIT, flags={origin_is_acl,} 
    #pkts encaps: 10, #pkts encrypt: 10, #pkts digest: 10 
    #pkts decaps: 10, #pkts decrypt: 10, #pkts verify: 10 
    #pkts compressed: 0, #pkts decompressed: 0 
    #pkts not compressed: 0, #pkts compr. failed: 0 
    #pkts not decompressed: 0, #pkts decompress failed: 0 
    #send errors 0, #recv errors 0 
     local crypto endpt.: 10.2.2.2, remote crypto endpt.: 10.1.1.1 
     path mtu 1500, media mtu 1500 
     current outbound spi: 249C5062 
     inbound esp sas: 
      spi: 0x7AA69CB7(2057739447) 
        transform: esp-aes esp-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5123, flow_id: 1, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4421281/3593) 
        IV size: 16 bytes 
        replay detection support: Y 
     inbound ah sas: 
      spi: 0x1214F0D(18960141) 
        transform: ah-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5121, flow_id: 1, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4421281/3593) 
        replay detection support: Y 
     inbound pcp sas: 
     outbound esp sas: 
      spi: 0x249C5062(614223970) 
        transform: esp-aes esp-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5124, flow_id: 2, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4421285/3593) 
        IV size: 16 bytes 
        replay detection support: Y 
     outbound ah sas: 
      spi: 0xB16D1587(2976716167) 
        transform: ah-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5122, flow_id: 2, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4421285/3592) 
        replay detection support: Y 
     outbound pcp sas:
      Step 2   Clear the IKE and IPsec SAs on Router B

      Example:
      Router# clear crypto isakmp
Router# clear crypto sa
Router# show crypto isakmp sa
  f_vrf/i_vrf   dst            src             state       conn-id slot 
       /        10.2.2.2.       10.1.1.1      MM_NO_STATE           1       0 (deleted)
Router# show crypto ipsec sa
interface: Ethernet1/0 
    Crypto map tag: testtag1, local addr. 10.2.2.2 
   protected vrf: 
   local  ident (addr/mask/prot/port): (10.0.2.2/255.255.255.255/0/0) 
   remote ident (addr/mask/prot/port): (10.0.0.1/255.255.255.255/0/0) 
   current_peer: 10.1.1.1:500 
     PERMIT, flags={origin_is_acl,} 
    #pkts encaps: 0, #pkts encrypt: 0, #pkts digest: 0 
    #pkts decaps: 0, #pkts decrypt: 0, #pkts verify: 0 
    #pkts compressed: 0, #pkts decompressed: 0 
    #pkts not compressed: 0, #pkts compr. failed: 0 
    #pkts not decompressed: 0, #pkts decompress failed: 0 
    #send errors 0, #recv errors 0 
     local crypto endpt.: 10.2.2.2, remote crypto endpt.: 10.1.1.1 
     path mtu 1500, media mtu 1500 
     current outbound spi: 0 
     inbound esp sas: 
     inbound ah sas: 
     inbound pcp sas: 
     outbound esp sas: 
     outbound ah sas: 
     outbound pcp sas:
      Step 3   Send traffic from Host 1 to Host 2 and ensure that new IKE and IPsec SAs are correctly established

      Example:
      ping 
Protocol [ip]: ip 
Target IP address: 10.0.2.2 
Repeat count [5]: 30 
Datagram size [100]: 100 
Timeout in seconds [2]: 
Extended commands [n]: no 
Sweep range of sizes [n]: n 
Type escape sequence to abort. 
Sending 30, 100-byte ICMP Echos to 10.0.2.2, timeout is 2 seconds: 
..!!!!!!!!!!!!!!!!!!!!!!!!!!!! 
Success rate is 93 percent (28/30), round-trip min/avg/max = 1/3/8 ms 
RouterB# show crypto isakmp sa
  f_vrf/i_vrf   dst            src             state       conn-id slot 
       /        10.1.1.1       10.2.2.2     QM_IDLE               3       0 
       /        10.1.1.1       10.2.2.2      MM_NO_STATE           1       0 (deleted) 
RouterB# show crypto ipsec sa
 
interface: Ethernet1/0 
    Crypto map tag: testtag1, local addr. 10.2.2.2 
   protected vrf: 
   local  ident (addr/mask/prot/port): (10.0.2.2/255.255.255.255/0/0) 
   remote ident (addr/mask/prot/port): (10.0.0.1/255.255.255.255/0/0) 
   current_peer: 10.1.1.1:500 
     PERMIT, flags={origin_is_acl,} 
    #pkts encaps: 28, #pkts encrypt: 28, #pkts digest: 28 
    #pkts decaps: 28, #pkts decrypt: 28, #pkts verify: 28 
    #pkts compressed: 0, #pkts decompressed: 0 
    #pkts not compressed: 0, #pkts compr. failed: 0 
    #pkts not decompressed: 0, #pkts decompress failed: 0 
    #send errors 0, #recv errors 0 
     local crypto endpt.: 10.2.2.2, remote crypto endpt.: 10.1.1.1 
     path mtu 1500, media mtu 1500 
     current outbound spi: D763771F 
     inbound esp sas: 
      spi: 0xE7AB4256(3886760534) 
        transform: esp-aes esp-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5127, flow_id: 3, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4502463/3596) 
        IV size: 16 bytes 
        replay detection support: Y 
     inbound ah sas: 
      spi: 0xF9205CED(4179647725) 
        transform: ah-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5125, flow_id: 3, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4502463/3596) 
        replay detection support: Y 
     inbound pcp sas: 
     outbound esp sas: 
      spi: 0xD763771F(3613619999) 
        transform: esp-aes esp-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5128, flow_id: 4, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4502468/3596) 
        IV size: 16 bytes 
        replay detection support: Y 
     outbound ah sas: 
      spi: 0xEB95406F(3952427119) 
        transform: ah-sha-hmac , 
        in use settings ={Tunnel, } 
        slot: 0, conn id: 5126, flow_id: 4, crypto map: testtag1 
        crypto engine type: Hardware 
        sa timing: remaining key lifetime (k/sec): (4502468/3595) 
        replay detection support: Y 
     outbound pcp sas: 
RouterA# show crypto isakmp sa
  f_vrf/i_vrf   dst            src             state       conn-id slot 
       /        10.2.2.2       10.1.1.1      MM_NO_STATE           1       0 (deleted) 
       /        10.2.2.2       10.1.1.1      QM_IDLE               2       0 
				Check for an invalid SPI message on Router B
Router# show logging
Syslog logging: enabled (10 messages dropped, 13 messages rate-limited, 0 flushes, 0 overruns, xml disabled) 
    Console logging: disabled 
    Monitor logging: level debugging, 0 messages logged, xml disabled 
    Buffer logging: level debugging, 43 messages logged, xml disabled 
    Logging Exception size (8192 bytes) 
    Count and timestamp logging messages: disabled 
    Trap logging: level informational, 72 message lines logged 
Log Buffer (8000 bytes): 
*Mar 24 20:55:45.739: %CRYPTO-4-RECVD_PKT_INV_SPI: decaps: rec'd IPSEC packet has invalid spi for 
        destaddr=10.2.2.2, prot=51, spi=0x1214F0D(18960141), srcaddr=10.1.1.1 
*Mar 24 20:55:47.743: IPSEC(validate_proposal_request): proposal part #1, 
  (key eng. msg.) INBOUND local= 10.2.2.2, remote= 10.1.1.1, 
    local_proxy= 10.0.2.2/255.255.255.255/0/0 (type=1), 
    remote_proxy= 10.0.0.1/255.255.255.255/0/0 (type=1), 
    protocol= AH, transform= ah-sha-hmac , 
    lifedur= 0s and 0kb, 
    spi= 0x0(0), conn_id= 0, keysize= 0, flags= 0x2 
*Mar 24 20:55:47.743: IPSEC(validate_proposal_request): proposal part #2, 
  (key eng. msg.) INBOUND local= 10.2.2.2, remote= 10.1.1.1, 
    local_proxy= 10.0.2.2/255.255.255.255/0/0 (type=1), 
    remote_proxy= 10.0.0.1/255.255.255.255/0/0 (type=1), 
    protocol= ESP, transform= esp-aes esp-sha-hmac , 
    lifedur= 0s and 0kb, 
    spi= 0x0(0), conn_id= 0, keysize= 0, flags= 0x2 
*Mar 24 20:55:47.743: IPSEC(kei_proxy): head = testtag1, map->ivrf = , kei->ivrf = 
*Mar 24 20:55:47.743: IPSEC(key_engine): got a queue event with 2 kei messages 
*Mar 24 20:55:47.743: IPSEC(spi_response): getting spi 4179647725 for SA 
        from 10.2.2.2        to 10.1.1.1     for prot 2 
*Mar 24 20:55:47.747: IPSEC(spi_response): getting spi 3886760534 for SA 
        from 10.2.2.2     to 10.1.1.1        for prot 3 
*Mar 24 20:55:48.071: IPSec: Flow_switching Allocated flow for flow_id 939524099 
*Mar 24 20:55:48.071: IPSec: Flow_switching Allocated flow for flow_id 939524100 
*Mar 24 20:55:48.135: IPSEC(key_engine): got a queue event with 4 kei messages 
*Mar 24 20:55:48.135: IPSEC(initialize_sas): , 
  (key eng. msg.) INBOUND local= 10.2.2.2, remote= 10.1.1.1, 
    local_proxy= 10.0.2.2/0.0.0.0/0/0 (type=1), 
    remote_proxy= 10.0.0.1/0.0.0.0/0/0 (type=1), 
    protocol= AH, transform= ah-sha-hmac , 
    lifedur= 3600s and 4608000kb, 
    spi= 0xF9205CED(4179647725), conn_id= 939529221, keysize= 0, flags= 0x2 
*Mar 24 20:55:48.135: IPSEC(initialize_sas): , 
  (key eng. msg.) OUTBOUND local= 10.2.2.2, remote= 10.1.1.1, 
    local_proxy= 10.0.2.2/0.0.0.0/0/0 (type=1), 
    remote_proxy= 10.0.0.1/0.0.0.0/0/0 (type=1), 
    protocol= AH, transform= ah-sha-hmac , 
    lifedur= 3600s and 4608000kb, 
    spi= 0xEB95406F(3952427119), conn_id= 939529222, keysize= 0, flags= 0xA 
*Mar 24 20:55:48.135: IPSEC(initialize_sas): , 
  (key eng. msg.) INBOUND local= 10.2.2.2, remote= 10.1.1.1, 
    local_proxy= 10.0.2.2/0.0.0.0/0/0 (type=1), 
    remote_proxy= 10.0.0.1/0.0.0.0/0/0 (type=1), 
    protocol= ESP, transform= esp-aes esp-sha-hmac , 
    lifedur= 3600s and 4608000kb, 
    spi= 0xE7AB4256(3886760534), conn_id= 939529223, keysize= 0, flags= 0x2 
*Mar 24 20:55:48.135: IPSEC(initialize_sas): , 
  (key eng. msg.) OUTBOUND local= 10.2.2.2, remote= 10.1.1.1, 
    local_proxy= 10.0.2.2/0.0.0.0/0/0 (type=1), 
    remote_proxy= 10.0.0.1/0.0.0.0/0/0 (type=1), 
    protocol= ESP, transform= esp-aes esp-sha-hmac , 
    lifedur= 3600s and 4608000kb, 
    spi= 0xD763771F(3613619999), conn_id= 939529224, keysize= 0, flags= 0xA 
*Mar 24 20:55:48.139: IPSEC(kei_proxy): head = testtag1, map->ivrf = , kei->ivrf = 
*Mar 24 20:55:48.139: IPSEC(mtree_add_ident): src 10.2.2.2, dest 10.1.1.1, dest_port 0 
*Mar 24 20:55:48.139: IPSEC(create_sa): sa created, 
  (sa) sa_dest= 10.1.1.1, sa_prot= 51, 
    sa_spi= 0xF9205CED(4179647725), 
    sa_trans= ah-sha-hmac , sa_conn_id= 939529221 
*Mar 24 20:55:48.139: IPSEC(create_sa): sa created, 
  (sa) sa_dest= 10.2.2.2, sa_prot= 51, 
    sa_spi= 0xEB95406F(3952427119), 
    sa_trans= ah-sha-hmac , sa_conn_id= 939529222 
*Mar 24 20:55:48.139: IPSEC(create_sa): sa created, 
  (sa) sa_dest= 10.1.1.1, sa_prot= 50, 
    sa_spi= 0xE7AB4256(3886760534), 
    sa_trans= esp-aes esp-sha-hmac , sa_conn_id= 939529223 
*Mar 24 20:55:48.139: IPSEC(create_sa): sa created, 
  (sa) sa_dest= 10.2.2.2, sa_prot= 50, 
    sa_spi= 0xD763771F(3613619999), 
    sa_trans= esp-aes esp-sha-hmac , sa_conn_id= 939529224 
ipseca-72a#

      Configuration Examples for Invalid Security Parameter Index Recovery

      Invalid Security Parameter Index Recovery Example

      The following example shows that invalid security parameter index recovery has been configured on Router A and Router B. Invalid Security Parameter Index Recovery Example shows the topology used for this example.

      Router A 

      Router# show running-config
Building configuration... 
Current configuration : 2048 bytes 
! 
version 12.3 
no service pad 
service timestamps debug datetime msec localtime 
service timestamps log datetime msec localtime 
no service password-encryption 
service tcp-small-servers 
! 
hostname ipseca-71a 
! 
logging queue-limit 100 
no logging console 
enable secret 5 $1$4GZB$L2YOmnenOCNAu0jgFxebT/ 
enable password lab 
! 
clock timezone PST -8 
clock summer-time PDT recurring 
ip subnet-zero 
! 
! 
no ip domain lookup 
! 
ip cef 
ip audit notify log 
ip audit po max-events 100 
mpls ldp logging neighbor-changes 
no ftp-server write-enable 
! 
! 
no voice hpi capture buffer 
no voice hpi capture destination 
! 
! 
crypto isakmp policy 1
  encryption aes
  authentication pre-share
  group 14 
  lifetime 180 
crypto isakmp key 0 1234 address 10.2.2.2
crypto isakmp invalid-spi-recovery 
! 
! 
crypto ipsec transform-set auth2 ah-sha-hmac esp-aes esp-sha-hmac 
! 
crypto map testtag1 10 ipsec-isakmp 
 set peer 10.2.2.2 
 set transform-set auth2 
 match address 150 
! 
! 
controller ISA 5/1 
! 
! 
interface FastEthernet0/0 
 ip address 10.1.1.1 255.0.0.0 
 no ip route-cache cef 
 duplex full 
 speed 100 
 crypto map testtag1 
! 
interface FastEthernet0/1 
 ip address 10.0.0.1 255.0.0.0 
 no ip route-cache cef 
 duplex auto 
 speed auto 
! 
interface Serial1/0 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 serial restart_delay 0 
 clockrate 128000 
! 
interface Serial1/1 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 serial restart_delay 0 
 clockrate 128000 
! 
interface Serial1/2 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 serial restart_delay 0 
! 
interface Serial1/3 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 no keepalive 
 serial restart_delay 0 
 clockrate 128000 
! 
ip classless 
ip route 10.3.3.3 255.0.0.0 10.2.0.1 
no ip http server 
no ip http secure-server 
! 
! 
access-list 150 permit ip host 10.0.0.1 host 10.0.2.2 
dialer-list 1 protocol ip permit 
dialer-list 1 protocol ipx permit 
! 
! 
call rsvp-sync 
! 
! 
mgcp profile default 
! 
! 
line con 0 
 exec-timeout 0 0 
line aux 0 
line vty 0 4 
 password lab 
 login 
! 
! 
end 
ipseca-71a#

      Router B

      Router# show running-config
Building configuration... 
Current configuration : 2849 bytes 
! 
version 12.3 
no service pad 
service timestamps debug datetime msec localtime 
service timestamps log datetime msec localtime 
no service password-encryption 
service udp-small-servers 
service tcp-small-servers 
! 
hostname ipseca-72a 
! 
logging queue-limit 100 
no logging console 
enable secret 5 $1$kKqL$5Th5Qhw1ubDkkK90KWFxi1 
enable password lab 
! 
clock timezone PST -8 
clock summer-time PDT recurring 
ip subnet-zero 
! 
! 
no ip domain lookup 
! 
ip cef 
ip audit notify log 
ip audit po max-events 100 
mpls ldp logging neighbor-changes 
no ftp-server write-enable 
! 
! 
no voice hpi capture buffer 
no voice hpi capture destination 
! 
! 
mta receive maximum-recipients 0 
! 
! 
crypto isakmp policy 1
  encryption aes
  authentication pre-share
  group 14 
  lifetime 180 
crypto isakmp key 0 1234 address 10.1.1.1 
crypto isakmp invalid-spi-recovery 
! 
! 
crypto ipsec transform-set auth2 ah-sha-hmac esp-aes esp-sha-hmac 
! 
crypto map testtag1 10 ipsec-isakmp 
 set peer 10.1.1.1 
 set transform-set auth2 
 match address 150 
! 
! 
controller ISA 5/1 
! 
! 
interface FastEthernet0/0 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 duplex half 
! 
interface Ethernet1/0 
 ip address 10.2.2.2 255.0.0.0 
 no ip route-cache cef 
 duplex half 
 crypto map testtag1 
! 
interface Ethernet1/1 
 ip address 10.0.2.2 255.0.0.0 
 no ip route-cache cef 
 duplex half 
! 
interface Ethernet1/2 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 duplex half 
! 
interface Ethernet1/3 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 duplex half 
! 
interface Ethernet1/4 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 duplex half 
! 
interface Ethernet1/5 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 duplex half 
! 
interface Ethernet1/6 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 duplex half 
! 
interface Ethernet1/7 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 duplex half 
! 
interface Serial3/0 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 serial restart_delay 0 
! 
interface Serial3/1 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 serial restart_delay 0 
 clockrate 128000 
! 
interface Serial3/2 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 serial restart_delay 0 
! 
interface Serial3/3 
 no ip address 
 no ip route-cache 
 no ip mroute-cache 
 shutdown 
 no keepalive 
 serial restart_delay 0 
 clockrate 128000 
! 
ip classless 
ip route 10.0.0.0 255.0.0.0 10.2.0.1 
no ip http server 
no ip http secure-server 
!
!
access-list 150 permit ip host 10.0.2.2 host 10.0.0.1 
dialer-list 1 protocol ip permit 
dialer-list 1 protocol ipx permit 
!
!
call rsvp-sync 
!
!
mgcp profile default 
! 
dial-peer cor custom 
!
!
gatekeeper 
 shutdown 
!
!
line con 0 
 exec-timeout 0 0 
 stopbits 1 
line aux 0 
 stopbits 1 
line vty 0 4 
 password lab 
 login 
!
!
end

      Additional References

      Related Documents

      Related Topic

      Document Title

      Configuring IKE

      Configuring Internet Key Exchange for IPsec VPNs

      Interface commands

      Cisco IOS Master Command List

      Recommended cryptographic algorithms

      Next Generation Encryption

      MIBs

      MIBs

      MIBs Link

      None.

      To locate and download MIBs for selected platforms, Cisco IOS software releases, and feature sets, use Cisco MIB Locator found at the following URL:

      http:/​/​www.cisco.com/​go/​mibs

      Technical Assistance

      Description

      Link

      The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

      http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

      Feature Information for Invalid Security Parameter Index Recovery

      The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

      Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.
      Table 1 Feature Information for Invalid Security Parameter Index Recovery

      Feature Name

      Releases

      Feature Information

      Invalid Security Parameter Index Recovery

      12.3(2)T 12.2(18)SXE

      When an invalid security parameter index error (shown as “Invalid SPI”) occurs in IP Security (IPsec) packet processing, the Invalid Security Parameter Index Recovery feature allows for an Internet Key Exchange (IKE) security association (SA) to be established. The “IKE” module sends notification of the “Invalid SPI” error to the originating IPsec peer so that Security Association Databases (SADBs) can be resynchronized and successful packet processing can be resumed.

      This feature was introduced in Cisco IOS Release 12.3(2)T.

      This feature was integrated into Cisco IOS Release 12.2(18)SXE.

      The following command was introduced or modified: crypto isakmp invalid-spi-recovery