5.1.2.13 Lab - Configuring OSPFv2 on a Multiaccess Network

Lab - Configuring OSPFv2 on a Multiaccess Network R1# show ip ospf interface GigabitEthernet0/1 is up, line protocol is up Internet Address 192.168.1.1/24, Area 0 Process ID 1, Router ID 192.168.31.11, Network Type BROADCAST, Cost: 1 Transmit Delay is 1 sec, State DR, Priority 255 Designated Router (ID) 192.168.31.11, Interface address 192.168.1.1 Backup Designated router (ID) 192.168.31.33, Interface address 192.168.1.3 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 oob-resync timeout 40 Hello due in 00:00:00 Supports Link-local Signaling (LLS) Index 1/1, flood queue length 0 Next 0x0(0)/0x0(0) Last flood scan length is 1, maximum is 2 Last flood scan time is 0 msec, maximum is 0 msec Neighbor Count is 2, Adjacent neighbor count is 2 Adjacent with neighbor 192.168.31.22 Adjacent with neighbor 192.168.31.33

(Backup Designated Router)

Suppress hello for 0 neighbor(s)

R3# show ip ospf interface GigabitEthernet0/1 is up, line protocol is up Internet Address 192.168.1.3/24, Area 0 Process ID 1, Router ID 192.168.31.33, Network Type BROADCAST, Cost: 1 Transmit Delay is 1 sec, State BDR, Priority 100 Designated Router (ID) 192.168.31.11, Interface address 192.168.1.1 Backup Designated router (ID) 192.168.31.33, Interface address 192.168.1.3 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 oob-resync timeout 40 Hello due in 00:00:00 Supports Link-local Signaling (LLS) Index 1/1, flood queue length 0 Next 0x0(0)/0x0(0) Last flood scan length is 0, maximum is 2 Last flood scan time is 0 msec, maximum is 0 msec Neighbor Count is 2, Adjacent neighbor count is 2 Adjacent with neighbor 192.168.31.22 Adjacent with neighbor 192.168.31.11

(Designated Router)

Suppress hello for 0 neighbor(s)

Which router is now the DR? R1 Which router is now the BDR? R3 Did the interface priority override the router ID in determining the DR/BDR?

Yes, the priority override the router id because the priority in the router is more important than the router id

© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public.

Page 5 of 6

Lab - Configuring OSPFv2 on a Multiaccess Network

Reflection 1.

List the criteria used from highest to lowest for determining the DR on an OSPF network.

By default the priority in the router is 1 because all of the 3 routers has the same priority, the start using the router id criteria and the highest router id become as DR. Priority R1 = 255 DR --> Router ID 192.168.31.11 Priority R3 = 100 BDR --> Router ID 192.168.31.33 Priority R2 = 0 BDROther --> Router ID 192.168.31.22 2.

What is the significance of a 255 interface priority?

The highest priority in a multi-access network using OSPF v2.

Router Interface Summary Table Router Interface Summary Router Model

Ethernet Interface #1

Ethernet Interface #2

Serial Interface #1

Serial Interface #2

1800

Fast Ethernet 0/0 (F0/0)

Fast Ethernet 0/1 (F0/1)

Serial 0/0/0 (S0/0/0)

Serial 0/0/1 (S0/0/1)

1900

Gigabit Ethernet 0/0 (G0/0)

Gigabit Ethernet 0/1 (G0/1)

Serial 0/0/0 (S0/0/0)

Serial 0/0/1 (S0/0/1)

2801

Fast Ethernet 0/0 (F0/0)

Fast Ethernet 0/1 (F0/1)

Serial 0/1/0 (S0/1/0)

Serial 0/1/1 (S0/1/1)

2811

Fast Ethernet 0/0 (F0/0)

Fast Ethernet 0/1 (F0/1)

Serial 0/0/0 (S0/0/0)

Serial 0/0/1 (S0/0/1)

2900

Gigabit Ethernet 0/0 (G0/0)

Gigabit Ethernet 0/1 (G0/1)

Serial 0/0/0 (S0/0/0)

Serial 0/0/1 (S0/0/1)

Note: To find out how the router is configured, look at the interfaces to identify the type of router and how many interfaces the router has. There is no way to effectively list all the combinations of configurations for each router class. This table includes identifiers for the possible combinations of Ethernet and Serial interfaces in the device. The table does not include any other type of interface, even though a specific router may contain one. An example of this might be an ISDN BRI interface. The string in parenthesis is the legal abbreviation that can be used in Cisco IOS commands to represent the interface.

© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public.

Page 6 of 6