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324Supports this theory and explains that OSPF starts by broadcasting hello packets In turn the packets lists each routers router ID which serves as each routers unique name or identifier for OSPF Graziani and Johnson 2008 discuss that by default hello packets are sent every 10 seconds on Ethernet and point to point segments However they are sent every 30 seconds on frame relay segments this frequent updates are to maintain neighbour adjacency Shapiro and Boyce 2006 explains that the dead interval specifies the period after which neighbouring routers consider that one router is down This is decided when the neighbouring routers have not received a response to the hello packet after a period of time Edgeworth Foss and Rios 2015 claims that the default timer for the dead interval is four times more than the hello packet timer Graziani and Johnson 2008 Clarifies that Edgeworth Foss and Rios 2015 statement is true as the Ethernet segment is 40 seconds and the frame relay segment is a 120 seconds Link state and Distance Vector Osterloh 2002 claims that routing protocols are separated into categories based on the algorithm they use to route data Routers running link state protocols identify neighbours and send broadcasts to update one another This happens through the exchange of link state advertisements or LSA s Clark 2003 describes that each router restricts the organisation of routing information which it floods to all other OSPF routers to its router LSA
However Balchunas 2012 claims that the protocol is in fact a hybrid routing protocol incorporating features of both distance vector and link state routing protocols Liu 2009 continues to discuss that the protocol addresses many of the limitations of other routing protocols including its predecessor Interior Gateway Routing Protocol IGRP Cisco 2017 discusses that EIGRP is suited for many different topologies and media In a well designed network EIGRP scales well Liu 2009 supports the claim by Cisco 2017 that this protocol supports many different topologies and adapts to scalability within networks Operation of DUAL Moraes 2011 explains that Enhanced Interior Gateway Routing Protocol bases its operation on the algorithm named diffused update algorithm dual Savage n d claims that the diffusing update algorithm constructs least cost paths to all reachable destinations on a network DUAL guarantees that each constructed path is loop free at every instant including periods of topology changes and network convergence Moraes 2011 EIGRP updates provide routers with the knowledge of a vector metric containing six parameters such as bandwidth delay reliability load MTU and hop count Angelescu 2010 supports and agrees with Moraes 2011 and Savage n d as DUAL uses the metrics to determine the least cost routes based on feasible successors The feasible successors are considered to be guaranteed loop free routing neighbours that will be used to forward packets reliably to the end destination Savage n d also adds that routers that are not affected by topology changes are not involved in the feasible successor recalculation