Amer Networks E5Web GUI User Manual
Page 287
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Use two ISPs, with one tunnel connecting through one ISP and the other tunnel connecting
through the other ISP. RLB can then be applied as normal with the two tunnels.
In order to get the second tunnel to function in this case, it is necessary to add a single host
route in the main routing table that points to the secondary ISPs interface and with the
secondary ISPs gateway.
This solution has the advantage of providing redundancy should one ISP link fail.
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Use VPN with one tunnel that is IPsec based and another tunnel that is uses a different
protocol.
If both tunnels must be, for example, IPsec connects, it is possible to wrap IPsec in a GRE
tunnel (in other words, the IPsec tunnel is carried by a GRE tunnel). GRE is a simple tunneling
protocol without encryption and therefore involves a minimum of extra overhead. See
Section 3.4.6, “GRE Tunnels” for more about this topic.
Chapter 4: Routing
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