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Load Balancing & Fault Tolerance
Tunnel Routing
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Tunnel Group
Consider the symmetric FortiWAN sites with multiple WAN links on each side, a
tunnel
between the two units are the
connection with one WAN link of local unit and one WAN link of remote unit. A
tunnel group
contains multiple tunnels
which might be various combinations of WAN links between the two FortiWAN units. A tunnel group is the basic unit to
be used for a Tunnel Routing transmission. Packets of a session transferred via tunnel routing between units would be
distributed (according to the balancing algorithms) to the multiple tunnels defined in the tunnel group. Therefore, a
tunnel group is logically a big tunnel that multiple WAN links are integrated to.
The figure below is an example to illustrate tunnels and tunnel groups. Tunnel Group 1 contains two tunnels which
tunnel 1 is established with FWN-A's WAN 1 and FWN-B's WAN 1, and tunnel 2 is established with FWN-A's WAN 2
and FWN-B's WAN 2. A transmission via Tunnel Group 1 will be distributed over tunnel 1 and tunnel 2. Tunnel Group 2
also contains two tunnels which tunnel 3 is established with FWN-A's WAN 3 and FWN-B's WAN 4, and tunnel 4 is
established with FWN-A's WAN 4 and FWN-B's WAN 3. Containing only one tunnel in a tunnel group, which is a
degenerate case, is allowed.
Tunnel group is the basic unit to be employed for tunnel routing transmission. Therefore, balancing algorithms,
encryption, the opposite site, tunnels in the group and even quality of the WAN links are the necessary associations for
a tunnel group transmission. To set up a tunnel group, here is the necessary information:
Which opposite FortiWAN unit the tunnel group is established with: Remote host ID
What are the tunnels included in the tunnel group: Local IP and Remote IP for a tunnel
How to distribute packets over the tunnels: Algorithm
Does the transmission keep in secret:Encryption
142
FortiWAN Handbook
Fortinet Technologies Inc.