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6.1 | Introduction to Static Routing | ||
| 6.1.4 | Configuring default route forwarding |
Default routes are used to route packets
with destinations that do not match any of the other routes in the
routing table. Routers are typically configured with a default route
for Internet-bound traffic, since it is often impractical and
unnecessary to maintain routes to all networks in the Internet. A
default route is actually a special static route that uses this
format:
The 0.0.0.0 mask, when logically ANDed to the destination IP address of the packet to be routed, will always yield the network 0.0.0.0. If the packet does not match a more specific route in the routing table, it will be routed to the 0.0.0.0 network. Use the following steps to configure default routes:
In the section Configuring Static Routes, static routes were configured on Hoboken to make networks 172.16.1.0 on Sterling and 172.16.5.0 on Waycross accessible. It should now be possible to route packets to both of these networks from Hoboken. However, neither Sterling nor Waycross will know how to return packets to any non-directly connected network. A static route could be configured on Sterling and Waycross for each of the non-directly connected destination networks. This would not be a scalable solution on a larger network. Sterling connects to all non-directly
connected networks via interface Serial 0. Waycross has only one connection
to all non-directly connected networks. This is through interface Serial 1. A
default route on both
Sterling and Waycross will provide routing for all packets that are
destined for non-directly connected networks.
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