H3C Technologies H3C S12500-X Series Switches - Manual (Page 153)

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IMPORTANT:
•
IPsec anti-replay is enabled by default. Failure to detect anti-replay attacks might result in denial of
services. Use caution when you disable IPsec anti-replay.
• Specify an anti-replay window size that is as small as possible to reduce the impact on system
performance.
• On a distributed device, multiple cards might process packets for the same VLAN interface or tunnel
interface. However, IPsec anti-replay requires packets sent and received on the same VLAN interface or
tunnel interface be processed by the same card. To implement IPsec anti-replay on a distributed device,
use the service command in VLAN or tunnel interface view to specify a card for forwarding the traffic on
the interface. For more information about the service command, see Layer 2—LAN Switching
Command Reference or Layer 3—IP Services Command Reference.
To configure IPsec anti-replay:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable IPsec anti-replay. ipsec anti-replay check
By default, IPsec anti-replay is
enabled.
3. Set the size of the IPsec
anti-replay window.
ipsec anti-replay window width The default size is 64.
245B
Binding a source interface to an IPsec policy
For high availability, a core device is usually connected to an ISP through two links, which operate in
backup or load sharing mode. The two interfaces negotiate with their peers to establish IPsec SAs
respectively. When one interface fails and a link failover occurs, the other interface needs to take some
time to re-negotiate SAs, resulting in service interruption.
To solve these problems, bind a source interface to an IPsec policy and apply the policy to both interfaces.
This enables the two physical interfaces to use the same source interface to negotiate IPsec SAs. As long
as the source interface is up, the negotiated IPsec SAs will not be removed and will keep working,
regardless of link failover.
Follow these guidelines when you perform this task:
• Only the IKE-based IPsec policies can be bound to a source interface.
• An IPsec policy can be bound to only one source interface.
• A source interface can be bound to multiple IPsec policies.
• If the source interface bound to an IPsec policy is removed, the IPsec policy becomes a common
IPsec policy.
• If no local address is specified for an IPsec policy that has been bound to a source interface, the
IPsec policy uses the IP address of the bound source interface to perform IKE negotiation. If a local
address is specified, the IPsec policy uses the local address to perform IKE negotiation.
To bind a source interface to an IPsec policy:
Step Command Remarks
1. Enter system view. system-view N/A