Ospf

Part – 1
Configured Single area OSPF
Part – 2
Database Table Size

Router-LSA Size Calculation –
R1’s Router LSA = 24 bytes + (10 x 12 bytes) = 144 bytes
R5’s Router LSA = 24 bytes + (07 x 12 bytes) = 108 bytes
R1’s Network LSA = 24 bytes + (2 x 4 bytes) = 32 bytes
LSA Type | Originating Router | Number of Links | Size |
Router-LSA | 1.1.1.1 | 10 | 144 |
Router-LSA | 2.2.2.2 | 10 | 144 |
Router-LSA | 3.3.3.3 | 10 | 144 |
Router-LSA | 4.4.4.4 | 10 | 144 |
Router-LSA | 5.5.5.5 | 7 | 108 |
Router-LSA | 6.6.6.6 | 7 | 108 |
Network-LSA | 13.13.13.2 | 2 | 32 |
Network-LSA | 24.24.24.1 | 2 | 32 |
Network-LSA | 34.34.34.2 | 2 | 32 |
Network-LSA | 56.56.56.2 | 2 | 32 |
Total database Size | 920 bytes |

Routing Table Size

Part – 3
3a) OSPF Database Size
ABR DB Size
  * Router LSA = 360 bytes
  * Network LSA = 64 bytes
  * Summary LSA = 1652 bytes
  * Total = 2076 bytes
NBR DB Size
  * Router LSA = 432 bytes
  * Network LSA = 64 bytes
  * Summary LSA = 728 bytes
  * Total = 1224 bytes

3a) Routing Table Size

Figure 1 – ABR

Figure 2 – NBR

Single Area OSPF | Multiple Areas OSPF |
| Area Border Router | Non-Area Border Router |
Database Size | Routing table Size | Database Size | Routing table Size | Database Size | Routing table Size |
920 bytes | 14144 bytes | 2076 bytes | 13780 bytes | 1224 bytes | 13068 bytes |

The routing table size of Single Area OSPF is more than Multi Area OSPF because in Single Area OSPF R1 and R2 has two extra loopback interfaces

ABR vs NBR
R3 will have t-1 & t-2of both area 0 & area 3, but R5 only have t1 & t2 of area 3.
So, R3 database size is higher than R5.
Also, R3 has area 1 & 2 t3’s.
ABR vs NBR
Routing table

3b) sections into areas will:
  * Reduce the LSA database because there will be less router & network LSAs
  * Small size of Router-LSA
  * Small routing table when summarizing routes at ABR
  * SPF calculation on...