Tag Archives: fortinet wan optimization

WAN optimization, web caching and memory usage

WAN optimization, web caching and memory usage

To accelerate and optimize disk access and to provide better throughput and less latency FortiOS WAN optimization uses provisioned memory to reduce disk I/O and increase disk I/O efficiency. In addition, WAN optimization requires a small amount of additional memory per session for comprehensive flow control logic and efficient traffic forwarding.

When WAN optimization is enabled you will see a reduction in available memory. The reduction increases when more WAN optimization sessions are being processed. If you are thinking of enabling WAN optimization on an operating FortiGate unit, make sure its memory usage is not maxed out during high traffic periods.

In addition to using the system dashboard to see the current memory usage you can use the get test wad 2 command to see how much memory is currently being used by WAN optimization. See “get test {wad | wccpd} <test_level>” for more information.

Configuring WAN optimization

Configuring WAN optimization

This chapter describes FortiGate WAN optimization client server architecture and other concepts you need to understand to be able to configure FortiGate WAN optimization.

Client/server architecture

Traffic across a WAN typically consists of clients on a client network communicating across a WAN with a remote server network. The clients do this by starting communication sessions from the client network to the server network. These communication sessions can be open text over the WAN or they can be encrypted by SSL VPN or IPsec VPN.

To optimize these sessions, you can add WAN optimization security policies to the client-side FortiGate unit to accept sessions from the client network that are destined for the server network. The client-side FortiGate unit is located between the client network and the WAN. WAN optimization security policies include WAN optimization profiles that control how the traffic is optimized.

The client-side FortiGate unit must also include the IP address of the server-side FortiGate unit in its WAN optimization peer configuration. The server-side FortiGate unit is located between the server network and the WAN, The peer configuration allows the client-side FortiGate unit to find the server-side FortiGate unit and attempt to establish a WAN optimization tunnel with it.

For the server-side FortiGate unit you must add a security policy with wanopt as the Incoming Interface. This security policy allows the FortiGate unit to accept WAN optimization sessions from the client-side FortiGate unit. For the server-side FortiGate unit to accept a WAN optimization connection it must have the client-side FortiGate unit in its WAN optimization peer configuration.

WAN optimization profiles are only added to the client-side WAN optimization security policy. The server-side FortiGate unit employs the WAN optimization settings set in the WAN optimization profile on the client-side FortiGate unit.

Client/server architecture

When both peers are identified the FortiGate units attempt to establish a WAN optimization tunnel between them. WAN optimization tunnels use port 7810. All optimized data flowing across the WAN between the client- side and server-side FortiGate units use this tunnel. WAN optimization tunnels can be encrypted use SSL encryption to keep the data in the tunnel secure.

Any traffic can be sent through a WAN optimization tunnel. This includes SSL and IPsec VPN traffic. However, instead of configuring SSL or IPsec VPN for this communication you can add SSL encryption using the WAN optimization tunnel.

In addition to basic identification by peer host ID and IP address you can configure WAN optimization authentication using certificates and pre-shared keys to improve security. You can also configure FortiGate units involved in WAN optimization to accept connections from any identified peer or restrict connections to specific peers.

The FortiClient application can act in the same manner as a client-side FortiGate unit to optimize traffic between a computer running FortiClient and a FortiGate unit.

WAN Optimization

WAN Optimization

WAN Optimization features require significant memory resources and generate a high amount of I/O on disk. Before enabling WAN Optimization, ensure that the memory usage is not too high. If possible, avoid other disk- intensive features such as heavy traffic logging on the same disk as the one configured for WAN Optimization needs.

In general, it is preferable to enable the Transparent Mode checkbox and ensure that routing between the two endpoints is acceptable. Some protocols may not work well without enabling Transparent Mode.

Other best practices for utilizing the WAN Optimization feature follow.

Sharing the WAN Opt. tunnel for traffic of the same nature

WAN optimization tunnel sharing is recommended for similar types of WAN optimization traffic (such as CIFS traffic from different servers). However, tunnel sharing for different types of traffic is not recommended. For example, aggressive and non-aggressive protocols should not share the same tunnel.

Ordering WAN Opt. rules appropriately

Precise, port specific WAN Optimization rules should be at the top of the list.
Generic rules, such as overall TCP, should be at the bottom of the list.

Avoiding mixing protocols in a WAN Opt. tunnel

Different protocols may be more or less talkative or interactive . Mixing protocols in a tunnel may result in a delay for some of them. It is recommended to define protocol specific wan-optimization rules and restrict the ports to the necessary ones only for performance reasons.

Setting correct configuration options for CIFS WAN Opt.

Ensure that the WAN Optimization rules cover TCP ports 139 and 445 (on the same or two different rules). Also ensure that Transparent Mode is selected.

Setting correct configuration options for MAPI WAN Opt.

For MAPI WAN Optimization, only specify a rule with TCP port 135 (unless the MAPI control port is configured differently). Derived data sessions using other random ports will be handled by the CIFS wan-optimization daemon even with only the control port configured.

Testing WAN Opt. in a lab

Ensure that WAN emulators are used to simulate the WAN. If no WAN emulator is used, it is expected to have better results without WAN Optimization than with WAN Optimization.
To test the difference between cold transfers (first-time transfers) and warm transfers, it is recommended to generate a random file of the cold transfer to ensure that the test is the first time that the file has been seen.

Regarding byte compression and type of file

Enabling byte compression on file transfers already compressed (.jpeg files, compressed archive, etc.) won’t provide any performance increase and could be seen as a misuse of CPU resources.

Regarding network address translation (NAT)

Selecting the NAT feature in a security policy does not have any influence on WAN Optimization traffic.

High Availability

There is no benefit to using active-active mode, so for pure WAN Optimization needs, use active-passive mode. Refer to the FGCP High Availability section for other best practices related to HA.

Authentication with specific peers

Configure WAN optimization authentication with specific peers. Accepting any peer is not recommended as this can be less secure.