Amer Networks E5Web GUI - Manual (Page 291)

Route # Interface Network Gateway
2 If2 192.168.0.0/24
Getting traffic from each network to and from the Internet is straightforward. Assuming only
outbound traffic, it requires only two Routing Rule objects. Assuming that each organization has
a public IPv4 address which maps to servers on the respective networks then outbound as well
as inbound traffic can be handled with the following four routing rules:
Route # Name Source If Source Net Dest Net Fwd Table Ret Table
1 org1-in wan all-nets pubip-org1 pbr1 pbr1
2 org1-out If1 all-nets all-nets pbr1 pbr1
3 org2-in wan all-nets pubip-org2 pbr2 pbr2
4 org2-out If2 all-nets all-nets pbr2 pbr2
This works if the two organizations do not need to communicate with each other. If they do, the
following two additional routing rules are also needed and are placed before the four above.
Route # Name Source if Source Net Dest Net Fwd Table Ret Table
1 org1-org2 If11 all-nets pubip-org2 pbr1 pbr2
2 org2-org1 If2 all-nets pubip-org1 pbr2 pbr1
With two organizations, two routing rules are enough to allow them to communicate. However,
with three organizations, six are needed; with four, twelve are needed; with five, twenty are
needed as so on. The numbers continue with an all-to-all mapping of 30, 42, 56 rules and the
administration task soon becomes unmanageable.
The Advantage of Virtual Routing
Virtual routing can eliminate the all-to-all mapping required with routing rules by using interface
routing table membership instead of routing rules. This reduces the complexity by creating 3
virtual systems which are represented by the router symbols in the diagram below.
Figure 4.10. The Advantage of Virtual Routing
Chapter 4: Routing
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