OSPF
– network commands: most specific wildcard mask first in the running config
– show ip ospf int brief: omits passive interfaces
– sh ip protocols: lists passive interfaces
– LAN: hello 10, dead 40, other: 30/120
– Authentication
ip ospf authentication/null/message-digest
ip ospf authentication-key/message-digest-key 1 md5 ROUTE
area X authentication
interface-n definialt authentication felülírja a globalt
– OSPF network types – táblázat
LSA Types
– Router (1)
Each router creates in the same area
Stub networks, transit networks
LSID: it’s own RID
ABR: one Type1 LSA per area
– Network (2)
DR creates LSA Type 2
Each router’s T1 LSA lists a connection to the pseudonode.
Pseudonode is modeled by the T2 LSA.
– Network Summary (3)
ABR creates for each subnet in one area, and advertise them into the other areas
ABR adds it’s own RID -> routers inside the area know how to reach them.
– Down – Attempt – Init – 2Way – Exchstart – Exchange – Loading – Full
– Exchstart: when sending the first DD (LSA Headers)
– Loading: LSR, LSU, LSAck
– Broadcast network: non-DR routers send to 224.0.0.6, DR sends to 224.0.0.5
– Periodic LSA reflood every 30 minutes
– Interarea routes: cost to the ABR + cost listed in T3 LSA
– ip ospf cost X
– route filtering: ABR (T3), ASBR (T5), route add to the routing table (distribute-list in)
– area X filter-list LISTNAME in/out
– area X range x.x.x.x y.y.y.y [cost X] – match the best metric by default, T3 LSA
– ASBR: summary-address. lowest metric, can not be set!
– Default routes: default-information originate
only if a default route exists in the routing table
E2 route, metric 1
always: default route is advertised even if there is not default route
– Stubby areas
stub: T5 LSA
totally stub: no T3, T5 LSA
NSSA: T5 LSA, new LSA Type: 7
totally NSSA: no T3, T5, but T7
default metric: 1
– area X default-metric Y – set on ABR. Can differ between ABRs. Default is 1.
– Virtual link: area X virtual-link REMOTE-RID
– Authentication: area X virtual-link RID authentication null/authentication-key/authentication message-digest
– Frame relay problems: no dynamic discovery, omitted broadcast keyword in frame-relay map command,
DR and BDR: full PVC connection to every other routers!
If not, manually configure every routes via a router which has a PVC to the destination
– neighbor NEXT-HOP-IP [cost]
