| Because scalable
internetworks experience change frequently, they must be able to
adapt to changes, such as the following:
Mixing routable and nonroutable protocols --- A network
delivering both routable and nonroutable traffic has some unique
problems. Routable protocols can be forwarded from one network to
another based on a network-layer address (such as an IP address).
Nonroutable protocols do not contain any network-layer address and
cannot be forwarded by routers. Most nonroutable protocols also lack
a mechanism to provide flow control and are sensitive to delays in
delivery. Any delays in delivery or packets arriving out of order
can result in session loss.
Integrating "islands" of networks --- Many companies
are integrating islands of networks that are typically using
different protocols in their hierarchical design. In this case, you
can add any protocols used by the network islands to the core layer,
or create a tunnel in the backbone that will connect the network
islands but not add new protocol traffic to the core backbone.
Meet the varying requirements for each protocol in the
internetwork ---
When multiple protocol traffic is present, the network must be
balanced between the special needs of each protocol.
Cisco IOS features that focus on network adaptability include:
EIGRP --- This routing protocol supports IP, IPX, and
AppleTalk traffic.
Redistribution --- You can exchange routing information
between networks that are using different routing protocols. Route
redistribution is a key feature in Cisco routers. Mastering the
usage of route redistribution is important to enable different
protocols to communicate with each other successfully.
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