Router R8
Configuration (also for R9, R10, R11)
R8(config)#int s0/0
R8(config-if)#ip address <ip addr> <subnet mask>
R8(config-if)#ip ospf priority <0 – 255> (Highest priority becomes DR. Default = 1. If it is 0, then won’t become DR)
R8(config)#int f0/0
R8(config-if)#ip address <ip addr> <subnet mask> (Ethernet interfaces for routers)
R8(config)#int loopback 0 (Overrides other interfaces to be Router ID)
R8(config-if)#ip address <ip addr> 255.255.255.255
R8(config-if)#ip ospf cost <1-65,535> (To set cost, otherwise based on bandwidth by default)
R8(config-if)#bandwidth <bandwidth > (in K, eg 64 to change from default. Eg serial - 1544K, Eth – 10M, Fa – 100M)
R8(config)ip route 0.0.0.0 0.0.0.0 <ip addr> (IP of outside world, eg R12)
R8(config)#Router OSPF <processID>
R8(config-router)#network <ip addr> <wildcard mask> area 0 (IP of our OSPF network. Area 0-4294967295. 0 is the Backbone area)
R8(config-router)#default-information originate (If neighbor router required to relay default route)
Router show and
debug commands
show run
show controllers
show controllers s0/0
show interfaces s0/0
show ip protocols
show ip route
show ip ospf [ database | neighbor detail | interface ]
debug ip ospf
OSPF uses Dijkstra Algorithm to select the best Shortest Path from the Topological Database and store them in the Forwarding Database (Routing Table).
OSPF Start Up. Highest Priority, and Router ID
Down
v
Init (Sending Type 1 Hellos)
v
Two-Way
Exstart (Sending Type 2 Hellos)
v
Exchange
v
Loading (Sending Type 3, 4, 5 Hellos)
v
Full
OSPF has 3 x Tables
Adjacency Database Recorded list of all information about Neighbors
Topological Database (
Forwarding Database Routing Table, generated by algorithm run on the Link State Database
OSPF Link Costs are based on Bandwidth by default. The following are the defaults by technology.
|
Technology Link Type |
Default Cost |
|
56K |
1785 |
|
64K |
1562 |
|
T1 (1.544 Mbps) |
64 |
|
E1 (2.048 Mbps) |
48 |
|
10 Mbps |
10 |
|
16 Mbps Token Ring |
6 |
|
100 Mbs Fast Ethernet, FDDI |
1 |