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CS4461: Difference between revisions
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-Options: allow for the IP header to be extended
-Data: the payload of the packet contains the transport-layer segment to be delivered
Link State Routing Algorithm:
The network topology and all link costs are known and available as input to the LS algorithm. Dijkstra's algorithm is popular.
Problem - oscillations in updates. A solution would be to mandate that no 2 routers can run the LS algorithm at the same time.
Popular LS Algorithm in use: OSPF
Distance Vector Routing Algorithm:
The DV algorithm is iterative and ''distributed'' meaning that each node receives information from one or more of its directly connected neighbors. It is iterative in that it continues until no more information is exchanged between neighbors.
Link-Cost change and Link Failure:
-At time t0, y detects the link-cost change
-updates its distance vector
-informs its neighbors of the change
-At time t1, z receives the update from y and updates its table
-it compares a new least cost to x
-sends its new distance vector to its neighbors
-At time t2, y receives z's update and updates its table
-y's least costs do not change
-y sends no messages to z
-Algorithm stabilizes
Popular DV Algorithm In Use: RIP
Border Gateway Protocol:
BGP is an inter-AS routing protocol. BGP provides each AS a means to
-Obtain subnet reachability information from neighboring ASs
-Propagate the reachability information to all routers internal to the AS
-Determine "good" routes to subnets based on the reachability information and on AS policy
Essentially BGP allow for a subnet to shout out "OMG I'M OVER HERE!!!!111!one"
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