Ipsec Implementation - HP MSR Series Configuration Manual

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AES—Encrypts plaintext data with a 128-bit, 192-bit, or 256-bit key. AES provides the highest
security strength and is slower than 3DES.
Crypto engine
The IPsec feature is resource intensive for its complex encryption/decryption and authentication
algorithms. To improve processing performance, you can use crypto engine to offload IPsec tasks.
The crypto engine processes all IPsec protected packets and hands the processed packets back to
the device for forwarding.
For more information about crypto engines, see

IPsec implementation

To implement IPsec protection for packets between two peers, complete the following tasks on each
peer:
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Configure an IPsec policy, which defines the range of packets to be protected by IPsec and the
security parameters used for the protection.
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Apply the IPsec policy to an interface or an application.
When you apply an IPsec policy to an interface, you implement IPsec based on the interface.
Packets received and sent by the interface are protected according to the IPsec policy. When you
apply an IPsec policy to an application, you implement IPsec based on the application. Packets of
the application are protected according to the IPsec policy, regardless of the receiving and sending
interface of the packets.
IPsec protects packets as follows:
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When an IPsec peer identifies the packets to be protected according to the IPsec policy, it sets
up an IPsec tunnel and sends the packet to the remote peer through the tunnel. The IPsec
tunnel can be manually configured beforehand, or it can be set up through IKE negotiation
triggered by the packet. The IPsec tunnels are actually the IPsec SAs. The inbound packets are
protected by the inbound SA, and the outbound packets are protected by the outbound SA.
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When the remote IPsec peer receives the packet, it drops, de-encapsulates, or directly
forwards the packet according to the configured IPsec policy.
Interface-based IPsec supports setting up IPsec tunnels based on ACLs.
ACL-based IPsec
To implement ACL-based IPsec, configure an ACL to define the data flows to be protected, specify
the ACL in an IPsec policy, and then apply the IPsec policy to an interface. When packets sent by the
interface match the permit rule of the ACL, the packets are protected by the outbound IPsec SA and
encapsulated with IPsec. When the interface receives an IPsec packet whose destination address is
the IP address of the local device, it searches for the inbound IPsec SA according to the SPI carried
in the IPsec packet header for de-encapsulation. If the de-encapsulated packet matches the permit
rule of the ACL, the device processes the packet. Otherwise, it drops the packet.
The device supports the following data flow protection modes:
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Standard mode—One IPsec tunnel protects one data flow. The data flow permitted by an ACL
rule is protected by one IPsec tunnel that is established solely for it.
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Aggregation mode—One IPsec tunnel protects all data flows permitted by all the rules of an
ACL. This mode is only used to communicate with old-version devices.
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Per-host mode—One IPsec tunnel protects one host-to-host data flow. One host-to-host data
flow is identified by one ACL rule and protected by one IPsec tunnel established solely for it.
This mode consumes more system resources when multiple data flows exist between two
subnets to be protected.
"Configuring crypto
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engines."