<Jeremy's IT Lab> Day 27: OSPF (part 2)

OSPF (part 2)

 

OSPF metric(cost):

-> cal base BW(speed) of int

* refer BW value / int BW *

ex) 100mbps / 10mbps = cost 10

-> can change refer BW, int BW

(1) refer BW

auto-cost reference-bandwidth 10000[megabits-per-sec] (greater than fastest )

(2) manual

ip spf cost 10[cost] bandwidth 10000[megabits-per-sec]

(3) int BW(not recommended)

loopback int cost = 1

 

 

Steps to be OSPF Neighbors:

1. Down : send hello (don't know neigbors RID)

2. Init : receive hello 

3. 2-way : reply hello (include its RID) -> send back hello (include full RID) -> DR/BDR election

4. Exstart : DBD packets, Master/Slave determinded

5. Exchange : DBD Packets, describe content of LSDB (LSAs)

6. Loading : LSR, LSU, LSAck (Share LSAs to sync LSDB)

7. Full : full adjacency (every 10 sec send, 'dead' timer 40 sec, if pass out remove neighbor)

 

**terms

DR: designated Router

BDR: backup designated router

DBD: Database description

LSR: Link state request

LSU: Link state update

 

Config OSPF:

1) activate directly

ip ospf [process-id] area [area]

2) config to passive int

passive-interface default

3) remove it

no passive-interface [interface-id]