OSPF and IS-IS are two main standard link state routing protocols designed
to operate in various complex network topologies. One aspect that both prot
ocols handle is the reliable dissemination of routing information over broa
dcast networks such as Ethernet and FDDI. Both protocols suggest different
schemes for this purpose, and in this article we compare the two. The perfo
rmance criteria being checked are: the longest arrival time of routing upda
te packets at all the routers; the total required bandwidth; and the number
of memory accesses a router performs, which is evidence of the amount of i
nternal work ii performs. We find that in our model of broadcast networks t
he scheme suggested in IS-IS is more efficient than that of OSPF in terms o
f the arrival times of routing update packets. In particular, the average a
rrival time of routing update packets in OSPF is 2-10 time; longer than in
IS-IS. In terms of the bandwidth each scheme consumes, there are scenarios
where OSPF outperforms IS-IS and vice verse. In terms of the number of memo
ry accesses routers perform in each scheme, IS-IS out-performs OSPF.