NP6, NP6XLite, and NP6Lite network processors provide fastpath acceleration by offloading communication sessions from the FortiGate CPU. When the first packet of a new session is received by an interface connected to an NP6 processor, just like any session connecting with any FortiGate interface, the session is forwarded to the FortiGate CPU where it is matched with a security policy. If the session is accepted by a security policy and if the session can be offloaded its session key is copied to the NP6 processor that received the packet. All of the rest of the packets in the session are intercepted by the NP6 processor and fast-pathed out of the FortiGate unit to their destination without ever passing through the FortiGate CPU. The result is enhanced network performance provided by the NP6 processor plus the network processing load is removed from the CPU. In addition the NP6 processor can handle some CPU intensive tasks, like IPsec VPN encryption/decryption.
NP6XLite and NP6Lite processors have the same architecture and function in the same way as NP6 processors. All of the descriptions of NP6 processors in this document can be applied to NP6XLite and NP6Lite possessors except where noted.
Session keys (and IPsec SA keys) are stored in the memory of the NP6 processor that is connected to the interface that received the packet that started the session. All sessions are fast-pathed and accelerated, even if they exit the FortiGate unit through an interface connected to another NP6. There is no dependence on getting the right pair of interfaces since the offloading is done by the receiving NP6.
The key to making this possible is an Integrated Switch Fabric (ISF) that connects the NP6s and the FortiGate unit interfaces together. Many FortiGate units with NP6 processors also have an ISF. The ISF allows any interface connectivity to any NP6 on the same ISF. There are no special ingress and egress fast path requirements as long as traffic enters and exits on interfaces connected to the same ISF.
Some FortiGate units, such as the FortiGate 1000D include multiple NP6 processors that are not connected by an ISF. Because the ISF is not present fast path acceleration is supported only between interfaces connected to the same NP6 processor. Since the ISF introduces some latency, models with no ISF provide low-latency network acceleration between network interfaces connected to the same NP6 processor.
Each NP6 has a maximum throughput of 40 Gbps using 4 x 10 Gbps XAUI or Quad Serial Gigabit Media Independent Interface (QSGMII) interfaces or 3 x 10 Gbps and 16 x 1 Gbps XAUI or QSGMII interfaces.
There are at least two limitations to keep in mind:
- The capacity of each NP6 processor. An individual NP6 processor can support between 10 and 16 million sessions. This number is limited by the amount of memory the processor has. Once an NP6 processor hits its session limit, sessions that are over the limit are sent to the CPU. You can avoid this problem by as much as possible distributing incoming sessions evenly among the NP6 processors. To be able to do this you need to be aware of which interfaces connect to which NP6 processors and distribute incoming traffic accordingly.
- The NP6 processors in some FortiGate units employ NP direct technology that removes the ISF. The result is very low latency but no inter-processor connectivity requiring you to make sure that traffic to be offloaded enters and exits the FortiGate through interfaces connected to the same NP processor.