| Probably the most important benefit of
routing is its proven history of facilitating networks, particularly
large networks. Although the Internet serves as the obvious example
here, this point is true for any type of network, such as a large
campus backbone. Because routers prevent broadcast propagation and
use more intelligent forwarding algorithms than bridges and
switches, routers provide much more efficient use of bandwidth. This
simultaneously results in flexible and optimal path selection. For
example, it is very easy to implement load balancing across multiple
paths in most networks when using routing. On the other hand, Layer
2 load balancing can be very difficult to design, implement, and
maintain. The data-forwarding benefits of routers are especially
important when multicast traffic is in use. As multicast traffic
becomes increasingly common in campus networks, routers will
continue to play an important role.
Routers provide additional benefits
that reach beyond the area of data forwarding. If Layer 3
addresses are hierarchical, routers can be used to implement designs
that utilize route summarization. Reducing routing protocol
overhead, increasing table lookup performance, and improving network
stability can further facilitate networks of almost unlimited size.
Most routers provide extensive access-list capabilities that can be
used to provide important policy controls. Finally, routers can also
provide important features such as Dynamic Host Configuration
Protocol (DHCP) relay, proxy Address Resolution Protocol (ARP), and
Get Nearest Server (GNS) functions in Internetwork Packet Exchange (IPX)
networks.
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