H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 366)

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Step Command Remarks
4. Specify the security
algorithms.
• Specify the encryption
algorithm for ESP:
esp encryption-algorithm
{ 3des | aes [ key-length ] |
des }
• Specify the authentication
algorithm for ESP:
esp authentication-algorithm
{ md5 | sha1 }
• Specify the authentication
algorithm for AH:
ah authentication-algorithm
{ md5 | sha1 }
Optional.
By default, the authentication and
encryption algorithms for ESP are
DES and MD5, and the
authentication algorithm for AH is
MD5.
5. Specify the IP packet
encapsulation mode for the
IPsec proposal.
encapsulation-mode { transport |
tunnel }
Optional.
Tunnel mode by default.
The AC does not support the
transport mode.
NOTE:
Changes to an IPsec proposal affect only SAs negotiated after the changes. To apply the changes to
existing SAs, execute the reset ipsec sa command to clear the SAs so that they can be set up using the
updated parameters.
Configuring an IPsec policy
IPsec policies define which IPsec proposals should be used to protect which data flows. An IPsec policy
is uniquely identified by its name and sequence number.
IPsec policies fall into two categories:
• Manual IPsec policy—The parameters are configured manually, such as the keys, the SPIs, and the
IP addresses of the two ends in tunnel mode.
• IPsec policy that uses IKE—The parameters are automatically negotiated through IKE.
Configuring a manual IPsec policy
To guarantee successful SA negotiations, follow these guidelines when configuring manual IPsec policies
at the two ends of an IPsec tunnel:
• The IPsec policies at the two ends must have IPsec proposals that use the same security protocols,
security algorithms, and encapsulation mode.
• The remote IP address configured on the local end must be the same as the IP address of the remote
end.
• At each end, configure parameters for both the inbound SA and the outbound SA and make sure
that different SAs use different SPIs.
• The local inbound SA must use the same SPI and keys as the remote outbound SA. The same is true
of the local outbound SA and remote inbound SA.