1. OSPF technical points
Open shortest path first open shortest path first protocol
Public protocol can be used on any brand of equipment
trigger update - periodic update
Periodic update = EIGRP has no periodic update, only triggered update
OSPF updates every 30 minutes and also triggers updates
Juniper
OSPF Vs EIGRP
The concept of OSPF area wants to keep part of the information only in its own area
EIGRP or OSPF
routing table topology table
Forward data - check routing table - save the best entry
- save all lines in the topology table
EIGRP - hello packet function - establish neighbor relationship
5s/15s
OSPF - hello packet function - establish neighbor relationship
10s 40s
2. The business of ospf is based on three tables
1. Neighbor table:
Neighbor router information
show ip ospf neighbor #View ospf neighbor
2. Topology table:
Also called link state database
show ip ospf database #View ospf database
3. Routing table:
The best path to reach the target network
show ip route #View routing table
3. Start several elements of OSPF:
1. Process number (area number) - locally effective (1-65535) - the number can be different between different devices - the number of connected interfaces must be the same
2. Announce the network segment (-establish neighbors to use and directly connect the network segment with the peer device-when telling others about your own network segment)
3. Which area to declare when announcing (area 0 is the benchmark)
===== One command to get it done!
Configure oSPF-configure router-.id==OSPF process ID
Router-idIp address arbitrary configuration - can not be repeated
Automatically select router-id
-The larger the RID from the loopback port becomes the router-id=
the larger the RID from the physical interface becomes the router-id
router priority
DR-designated router used in the election of DR and BDR in OSPF -big brother
BDR-backup designated router-second brother
-DROTHERS-little brother
4. How to vote
1. OSPF interface priority election default priority = 1
Can be modified = equivalent to artificial designation (the bigger the better)
2. If compare router-id by default (the bigger the better)
Theoretical level - the above theory is the concept
Actually:
Which device starts first is the DR
The existing DR is preconceived. No matter how high the priority of the newly added device is, it cannot preempt it. It can only preempt the role of the BDR after the existing BDR is upgraded when the existing DR restarts or goes down.