HOMEWORK ASSIGNMENT

Week 5

45 Points Maximum

Name _Jalisa Bowman______________________

NETW204

Homework #5

Due Date April 1, 2018____________________________

Professor _Lynn Risley___________________________ 

OSPF

1. Given the diagram below and OSPF properly configured on routers 1 and 2. The network engineer typed two Cisco IOS commands in the Command Line Interface (CLI) back to back and observed the output below.

Explain how the cost to the 192.168.1.0/24 route was calculated in OSPF. (15 points)

R2#show ip route

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default,

O 192.168.1.0/24 [110/65] via 192.168.23.1, 00:03:44, Serial0/3/0

O 192.168.2.0/24 [110/65] via 192.168.23.1, 00:03:44, Serial0/3/0

192.168.3.0/24 is variably subnetted, 2 subnets, 2 masks

C 192.168.3.0/24 is directly connected, GigabitEthernet0/0

192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks

C 192.168.23.0/24 is directly connected, Serial0/3/0

!

! Removal of unnecessary lines.

R2#show interface s0/3/0

Serial0/3/0 is up, line protocol is up (connected)

Hardware is HD64570

Internet address is 192.168.23.2/24

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation HDLC, loopback not set, keepalive set (10 sec)

!

! Removal of unnecessary lines.

R2#

In general, cost = reference / bandwidth and it appears the reference is 20000 usec with the BW of 1544. 20000/1544 = 12.953 rounded up to 13. But the command ip ospf cost cost_value in the interface can change the ospf cost.

2. Explain the steps that two routers take to become fully adjacent neighbors in OSPF. (15 Points)

Router1>enable

#Configure terminal

#Router ospf 1

#Network 192.168.0.0 0.0.0.255 area 0

#network 172.14.0.0 0.0.0.255 area 0 exit

Router1#show ip protocols

#show ip route exit

Router2#configure terminal

#router ospf 1

#router-id 172.14.0.2

#network 192.168.16.0 0.0.0.255 area 1

#network 172.14.0.0 0.0.0.255 area 0

Exit

Router2#show ip protocols

#show is ospf neighbor

SW1#configure terminal

#router ospf 1

#network 172.16.0.0 0.0.0.255 area 0

#network 172.14.0.0 0.0.0.255 area 0

3. Explain the difference between DR, BDR, and DROTHER. How would you go about changing the BDR to DR assuming all the routers are up and operational (nothing went down)? What would be the impact of such a change on a live or production network? (15 points) DR is the Designated Router and another BDR is designed to be a Backup Designated Router. One is the primary and one is the back up protocol when DR and BDR serve as the central point for exchanging OSPF routing information. Every router in a network establish a full neighbor relationship with the DR and the BDR. Which ever router with the highest priority will become the DR and the second highest priority or router ID will become the BDR.

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