ospf

Question 1

how do you find a router ID in ospf

Answer 1

ospf router id is the ip of the loopback interface. This can be found using this command show ip protocols

Question 2

how do you advertise a loopback interface on ospf bearing in mind they have a subnet mask of /32

Answer 2

you use /24 or /16 when advertising the network of the loopback int ips. it does not matter if they are /32
eg: ip add 192.168.0.0 0.0.255.255 area 0

Question 3

what is reference bandwidth and how do you configure it in ospf

Answer 3

reference bandwidth defines a link speed that has an ospf cost of 1
auto-cost reference-bandwidth 100000 for 100gps to have a cost of 1 etc

Question 4

what is the formular for calculating ospf cost

Answer 4

ospf cost = reference bandwidth/interface bandwidth

Question 5

how do you modify the ospf cost on an interface

Answer 5

ip ospf cost x(eg 1500) used to load balance traffic.