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As
networks grow in size, routing tables (tell
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next
destinations on way to receiver) grow
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Partial
solution: use default entries
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Hierarchical
routing:
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networks
organized (recursively) into subnetworks.
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Routing
problem reduces to two smaller subproblems
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routing
between subnetworks (with relatively stable
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topology)
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routing
with subnetwork (with dynamically changing
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topology)
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requires
identifiable structure of network addresses
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(IP
addresses: class A, B, C)
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Another
problem addressed at network layer:
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mobility
(mobile-IP)
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Congestion
control: ensure efficient network
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usage,
do not overload internal routers or links:
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pre-allocate
buffers, discard packets, choke packets,
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etc....
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