This section will cover the configuration settings found under the WAN Virtualization Advanced tab.
Advanced Tunnel Configuration
This section allows the enabling/disabling of specific tunnels. This can be used in the case of mixed private/public end point configurations where some tunnels won't work due to one end point belonging to a private network and the other on the public Internet. Furthermore, the Auto Testing define basic testing thresholds for each tunnel but can be overridden by disabling Auto Testing and assigning custom testing and timeout values. Increasing the testing and time out values is recommended if certain tunnels are "bouncing" (rapidly changing between up and down states).
LAN Traffic Identification
This section is expandable to show what local and remote LAN subnets are classified as "interesting" traffic to be put into WAN Virtualization. In current versions, it is no longer recommended to use LAN Traffic Identification, instead it is recommended to create static routes to identify the interesting traffic and route it into WAN Virtualization.
WAN Virtualization or "Channel Bonding" Static Routes
By default, all traffic put inside the WAN Virtualization tunnels will be load balanced based on tunnel weighting. The WAN Virtualization Static Routes section provides a means to prefer a particular tunnel for certain traffic. The article WAN Virtualization Cases and Configuration includes examples for when routes would be used. Making changes to WAN Virtualization or "Channel Bonding" Static Routes will not bounce the WAN Virtualization tunnel for the site that you are configuring the static route for.
Packet options setting defines the fragmentation behaviour when sent over multiple tunnels.
- Normal: This is the default option which will fragment each packet only if it is large enough to do so based on the weight ratio of the selected tunnels. This option does the best job of load balancing accurately according to the tunnel weights.
- No Fragment: Select this option to never fragment packets over multiple tunnels. This option offers higher throughput performance, but may cause latency jitter when used with WAN lines that have greatly different latency characteristics. For that reason, it may not be suitable for applications that are sensitive to jitter such as VoIP and other real-time traffic.
- Always Fragment: Select this option to always fragment each packet over selected tunnels. This option will always fragment even small packets. If traffic consists of mostly small packets this may result in less accurate load balancing according to tunnel weight ratios.
- Duplicate Optionally select this option to duplicate and send every matching packet out each selected tunnel. Note that this will reduce performance and should only be used when seamless tunnel failover is desired. Seamless failover is achieved because as long as at least one copy of the packet makes it to its destination there will be no packet loss.
Changes in version 10.5
Starting in version 10.5, the default WAN Virtualization (WV) static route uses Session Load Balancing for all traffic that is not classified by another WV static route. All enabled tunnels with weight > 0 will be used by the default WV route.
Packets that match a WV static route will get sent over the configured tunnels for that route. As long as any configured tunnels for the route are up, traffic will be sent on those tunnels. If all configured route tunnels are down, traffic will then be sent on any remaining operational tunnels.
Redefined Packet Options
- Aggregate: Send a packet down multiple tunnels by fragmenting the packet.
- Load Balance: Send whole packets over multiple tunnels in a round-robin manner.
- Duplication: Send identical packets down two or more tunnels.
- Session Load-balancing:
- Keep sessions entirely on a single tunnel.
- Multiple sessions will be distributed roughly equal over all tunnels.
- Both sites must have symmetrical session LB configurations
- Send packets on only the selected tunnels that are currently up.
- If none of the selected tunnels are up, send packets on other available tunnels (no blackhole).
- Sends packets on selected tunnels even if conditions exceed configured Max RTT/Loss thresholds.
Tunnels that have exceeded their Max RTT/Loss values, or are experiencing congestions according to the Dynamic Reweighting algorithm, will have a weight of 0 and will not be used for sending unless the ‘Fixed’ option is enabled in the WV SR. Tunnels whose computed weights are less than 0 are considered stand-by, and will only be used if no tunnels weighted >= 0 are up.