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Cooper Bussmann 245U-E Wireless Ethernet Modem & Device Server User Manual
Rev Version 2.19
Figure 62 Gateway Address
3.18 Routing
When a 245U-E receives an IP frame that is destined for an IP address on a different network, it checks if the
network address matches the network address of one of its own interfaces (hard-wired Ethernet, or wireless
Ethernet, or WDS) and forwards the frame appropriately. However, if the IP network address does not match the
network address of any of its interfaces, the 245U-E will forward the frame to its default gateway. In this case it is
assumed that the default gateway has a valid route to the destination.
In some cases, it is not practical to have just one default gateway. For example, this is true for routed wireless
networks with more than two 245U-E routers, and in some cases when WDS router interfaces are used. If more
than one next-hop router is required, the 245U-E allows for up to 30 routing rules to be configured. A routing rule
specifies a destination network (or host) IP address and the corresponding next-hop router to which messages for
the specified destination will be forwarded. It is assumed that the next-hop router (or gateway) will then deliver the
data to the required destination (or forward it on to another router that will).
Figure 63 Routing
Figure 63 illustrates a situation where routing rules may need to be configured. In this example, the 245U-E
clients need only specify the access point as their default gateway (they require no routing rules to be configured).
However, for the access point to be able to deliver traffic to LAN B and LAN C it needs to have routing rules
configured that specify the respective 245U-E client and routers as next-hop routers (gateways) to networks
B and C. Note that devices on LAN A should specify the 245U-E access point as their default gateway. An
alternative to adding routing rules to the 245U-E in this example would be for each device on LAN A that needs to
communicate with LANs B and C to have independent routing rules specifying the 245U-E clients at B and C as
gateways to those networks.
The routing rules for the access point in the Figure 63 are shown in Figure 64. The first entry shows the route to
LAN B. The gateway for the route to LAN B is configured as the wireless IP address of the 245U-E client connected
to LAN B. The destination for the route is configured as the network address of LAN B. Because the host ID of the