OSPF Features
OSPF Hierarchy
configuring and Verifying OSPF
OSPF Details
Link State Protocol
100% loop free topology
Fast convergence
Classless routing - understands variable length subnet mask (VLSM)
Use Cost (Bandwidth) as Metric
Sends Partial updates only LSA - only when network change
Administrative Distance is 110
router(config)# router ospf <process-id> - internal number on router
router(config-router)# network <network> <wildcard-mask> area <area-id> - start helo packets
Example
routerA(config)# router ospf 5
routerA(config-router)# network 192.168.1.0 0.0.0.0.5 area 0
routerA(config-router)# network 12.12.12.0 0.0.0.0.5 area 0
routerA(config-router)# network 13.13.13.0 0.0.0.0.5 area 0
OSPF configuration
routerA Fe0/1 192.168.1.1/24, S0/0/0 12.12.12.1/24, S0/0/1 12.12.12.1/24
routerB Fe0/1 192.168.2.1/24, S0/0/0 12.12.12.2/24, S0/0/1 13.13.13.1/24
routerc Fe0/1 192.168.3.1/24, S0/0/0 12.12.12.2/24, S0/0/1 13.13.13.1/24
OSPF Configuration Verification
routerA# show ip protocols (displays info about all routing protocols running on the router)
routerA# show ip route (displays the routing table of the router)
routerA# show ip ospf neighbor (displays the OSPF neighbor Table)
routerA# show running-config (Displays the Routers running configurations)
Redistribute a static or directly connect routes into OSPF
MUST follow this order
1. create prefix list
2. create router map
3. create ospf redistribution
see example in router
Step 1
ip prefix-list connected_into_ospf seq 5 permit 10.85.246.2/32 (prefix listed for the router map)
!
ip prefix-list static_into_ospf seq 5 permit 10.85.246.128/25
Step 2
!
route-map connected_into_opsf permit 10
match ip address prefix-list connected_into_opsf
set tag 1002
!
Step 3
router ospf 3768
log-adjacency-changes
area 853 authentication message-digest
redistribute connected metric-type 1 subnets route-map connected_into_opsf
redistribute static metric 1 subnets route-map static_into_ospf
passive-interface Loopback0
network 10.85.246.12 0.0.0.3 area 853
