Connecting multiple ISPs

Monomode:

One physical port per outside interface/link, no switch is required,
crossover cables are used to connect the routers and firewall  to the Elfiq unit.

Multimode:

In this scenario for connecting multiple ISPs, one physical port is the outside interface  and is connected to an unmanaged switch or the untagged VLAN of a switch. All the ISP links are  connected to the switch. This mode also supports more  links than the available number of physical Ethernet ports on the Elfiq unit. 

Monomode with VLANs:

One physical port is an 802.1q trunk with multiple outside interfaces. A switch supporting VLAN trunking is required  for this type of installation. Each outside interface operates in its own VLAN and is connected to a link.  VLANs are also required when monomode can not be used (more links than the number of available physical Ethernet ports) or when links are not compatible with multimode (multiple DHCP or PPPoE links can not share the same layer 2 network).

Mixed Mode:

This configuration is typically used and recommended for single unit installations with more than two links and where the LAN Failsafe feature is used. The inside and primary link outside interfaces are configured with the LAN Failsafe ports. Alternates links are configured on different outside interface(s) with an alternate physical port and a switch. This mode isolates at layer 2 the primary link devices and router from the alternate links and allows to support more links than the number of available physical Ethernet ports for outside interfaces.