Flashcards
Routing Architecture
Cards in this deck (15)
- 1Static RoutingFixes routes at boot time
Useful only for simplest cases - 2Dynamic RoutingTable initialized at boot time
Values inserted / updated by protocols that propagate route information
Necessary in large internets - 3Routing with partial informationThe routing table in a given router contains partial information about possible destinations. Routing that uses partial information allows sites autonomy in making local routing changes, but introduces the possibility of inconsistencies that may make some destinations unreachable from some sources.
- 4Original internetBackbone network plus routers each connecting a local network
- 5Worst Case If All Routers contain A Default RouteDatagram sent to nonexistent destination loops until TTL expires
- 6Original Routing ArchitectureSmall set of ‘‘core’’ routers with complete information about all destinations
Other routers know local destinations and use the core as central router - 7Disadvantage of original core routing architectureCentral bottleneck for all traffic
No shortcut routes possible
Does not scale - 8Original two backbones of the internetNSF and ARPA
- 9Expanding the topology to multiple backbonesmakes routing complex;
attempting to partition the core architecture so that all routers use default routes introduces potential routing loops. - 10Core routing architectureAssumes a centralized set of routers serves as the repository of information about all possible destinations in an internet.
Core systems work best for internets that have a single, centrally managed backbone. - 11General idea of core routing architectureHave a set of core routers know routes to all locations
Devise a mechanism that allows other routers to contact the core to learn routes (spread necessary routing information automatically)
Continually update routing information - 12Two basic algorithms used by routing update protocolsDistance-vector
Link-state - 13Distance-Vector AlgorithmInitialize routing table with one entry for each directly connected network
Periodically run a distance-vector update to exchange information with routers that are reachable over directly connected networks - 14Link-State AlgorithmAllow each router to compute shortest paths
Avoids problem where one router can damage the entire internet by passing incorrect information - 15Routing Tables can beInitialized at startup (host or router)
Updated dynamically (router)
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- Networks Flashcards on Routing Architecture, created by M KB on 06/11/2018.
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- M KB
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