R3721-F3210-F3171-HP High-End Firewalls VPN Configuration Guide-6PW101

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Analysis
When multiple devices create different IPsec tunnels early or late, a device may have multiple peers. If the
device is not configured with ACL rule, the peers send packets to it to set up different IPsec tunnels in
different protection granularity respectively. As the priorities of IPsec tunnels are determined by the order
they are established, a device cannot interoperate with other peers in fine granularity when its outbound
packets are first matched with an IPsec tunnel in coarse granularity.
Solution
When a device has multiple peers, configure ACLs on the device to distinguish different data flows and
try to avoid configuring overlapping ACL rules for different peers. If it is unavoidable, configure sub-rules
in fine granularity with higher preferences.