H3C SOHO IE4300, Command Reference Manual

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Usage guidelines
IPsec packet de-encapsulation involves complicated calculation. De-encapsulation of replayed
packets is not necessary but consumes large amounts of resources and degrades performance,
resulting in DoS. IPsec anti-replay checking, when enabled, is performed before the
de-encapsulation process, reducing resource waste.
In some situations, service data packets are received in a different order than their original order. The
IPsec anti-replay feature drops them as replayed packets, which impacts communications. If this
happens, disable IPsec anti-replay checking or adjust the size of the anti-replay window as required.
Only IPsec SAs negotiated by IKE support anti-replay checking. Manually created IPsec SAs do not
support anti-replay checking. Enabling or disabling IPsec anti-replay checking does not affect
manually created IPsec SAs.
Examples
# Enable IPsec anti-replay checking.
<Sysname> system-view
[Sysname] ipsec anti-replay check
Related commands
ipsec anti-replay window
ipsec anti-replay window
Use ipsec anti-replay window to set the anti-replay window size.
Use
undo ipsec anti-replay window
to restore the default.
Syntax
ipsec anti-replay window width
undo ipsec anti-replay window
Default
The anti-replay window size is 64.
Views
System view
Predefined user roles
network-admin
Parameters
width : Specifies the size for the anti-replay window. It can be 64, 128, 256, 512, or 1024 packets.
Usage guidelines
Service data packets might be received in a very different order than their original order, and the
IPsec anti-replay feature might drop them as replayed packets, affecting normal communications. If
this happens, disable IPsec anti-replay checking or adjust the size of the anti-replay window as
required.
Changing the anti-replay window size affects only the IPsec SAs negotiated later.
Examples
# Set the size of the anti-replay window to 128.
<Sysname> system-view
[Sysname] ipsec anti-replay window 128