> # Optional IKE Parameter Configuration

> You can optionally configure the following parameters for the IKE feature:

> - The lifetime association within each policy—The lifetime ranges from 600 to 86,400 seconds. The default is 86,400 seconds (equals one day). The lifetime association within each policy is configured when you are creating an IKE policy. See the "Configuring an IKE Policy" topic.
> - The keepalive time for each peer if you use IKEv2—The keepalive ranges from 120 to 86,400 seconds. The default is 3,600 seconds (equals one hour).
> - The initiator version for each peer—IKE v1 or IKE v2 (default). Your choice of initiator version does not affect interoperability when the remote device initiates the negotiation. Configure this option if the peer device supports IKEv1 and you can play the initiator role for IKE with the specified device. Use the following considerations when configuring the initiator version with FCIP tunnels:
> - If the switches on both sides of an FCIP tunnel are running MDS SAN-OS Release 3.0(1) or later, or Cisco NX-OS 4.1(1) you must configure initiator version IKEv1 on both sides of an FCIP tunnel to use only IKEv1. If one side of an FCIP tunnel is using IKEv1 and the other side is using IKEv2, the FCIP tunnel uses IKEv2.
> - If the switch on one side of an FCIP tunnel is running MDS SAN-OS Release 3.0(1) or later, or Cisco NX-OS 4.1(1b) and the switch on the other side of the FCIP tunnel is running MDS SAN-OS Release 2.x, configuring IKEv1 on either side (or both) results in the FCIP tunnel using IKEv1.

> Note Only IKE v1 is supported to build IPsec between 2.x and 3.x MDS switches.

> Caution | You may need to configure the initiator version even when the switch does not behave as an IKE initiator under normal circumstances. Always using this option guarantees a faster recovery of traffic flows in case of failures.

> Tip The keepalive time only applies to IKEv2 peers and not to all peers.

> Note When IPsec implementations in the host prefer to initiate the IPsec rekey, be sure to configure the IPsec lifetime value in the Cisco MDS switch to be higher than the lifetime value in the host.

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