Cisco

Cisco CCNP - OSPF Lab 1

This article will describe the first CCNP MPLS lab.

Initial Configuration

Getting Command Line Access

Answer no to the initial configuration dialogue.

% Please answer 'yes' or 'no'.
Would you like to enter the initial configuration dialog? [yes/no]: n

Change from user mode to privileged mode

Router>enable
Router#

Change to configure mode

Router#configure 
Configuring from terminal, memory, or network [terminal]? terminal   
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#

Adding Base Configuration

configure terminal
hostname R1  
ip domain-name infoitech.co.uk

Securing Access

configure terminal
line console 0
password cisco
login

Require a password when logging in to the console.

configure terminal
line aux 0
password cisco
login

Require a password when logging in to the Aux Port.

Saving the Configuration

R1#copy running-config startup-config
Destination filename [startup-config]? startup-config
Building configuration...
[OK]

Configuring Interfaces

Let's configure the interfaces according to the diagram below.

configure terminal
int lo0
ip address 10.0.0.1 255.255.255.255

Configuring the Loopback interface.

configure terminal
interface GigabitEthernet 0/0
ip address 10.1.2.1 255.255.255.0
description "R1 to R2"
no shutdown

Interface facing R2

configure terminal
interface GigabitEthernet 0/1
ip address 10.1.3.1 255.255.255.0
description "R1 to R3"
no shutdown

Interface facing R3

show interfaces description

Interface                      Status         Protocol Description
Gi0/0                          up             up       "R1 to R2"
Gi0/1                          up             up       "R1 to R3"
Gi0/2                          admin down     down     
Gi0/3                          admin down     down     
Lo0                            up             up

Repeat the steps above for R2 and R3 changing the commands accordingly.

Configuring OSPF

Enabling OSPF

Let's enable debug mode on OSPF hello messages.

debug ospf hello

Let's enable the OSPF process.

configure terminal
router ospf 1

The number 1 is the process number and is local to the router. The purpose of the process is to allow for multiple OSPF instances on the router.

OSPF Network Configuration

OSPF can be configured on an interface in two ways. In the example below, OSPF is configured using subnets, and the interfaces configured with the specified subnets will be OSPF enabled.

This LAB uses a single OSPF area 0 on the CORE routers.

The network command enables OSPF in any interface that matches the subnet and wildcard mask. A wildcard 0.0.0.0 will match only a single IP address.

configure terminal
router ospf 1
network 10.1.2.1 0.0.0.0 area 0
network 10.1.3.1 0.0.0.0 area 0

As seen in the output from the command below. The interface GigabitEthernet0/1 OSPF configuration was attached via a network statement.

show ip ospf interface

GigabitEthernet0/1 is up, line protocol is up 
  Internet Address 10.1.3.1/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 10.0.0.1, Network Type BROADCAST, Cost: 1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 10.0.0.1, Interface address 10.1.3.1
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:06
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/2/2, flood queue length 0
  Next 0x0(0)/0x0(0)/0x0(0)
  Last flood scan length is 0, maximum is 0
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 0, Adjacent neighbor count is 0 
  Suppress hello for 0 neighbor(s)

OSPF Interface Configuration

OSPF can also be configured on the interface. Let's configure an interface in R2 using the per-interface commands.

configure terminal
interface gigabitEthernet0/0
ip ospf 1 area 0
exit

Using the command below, we can see that the interface gigabitEthernet0/0 is reporting that OSPF was attached via Interface Enable.

show ip ospf interface

GigabitEthernet0/0 is up, line protocol is up 
  Internet Address 10.1.2.2/24, Area 0, Attached via Interface Enable
  Process ID 1, Router ID 10.0.0.2, Network Type BROADCAST, Cost: 1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Enabled by interface config, including secondary ip addresses
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 10.0.0.2, Interface address 10.1.2.2
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:05
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/1/1, flood queue length 0
  Next 0x0(0)/0x0(0)/0x0(0)
  Last flood scan length is 0, maximum is 0
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 0, Adjacent neighbor count is 0 
  Suppress hello for 0 neighbor(s)

OSPF Network Type

By default, the OSPF network type is set as BROADCAST and it needs to be changed to point-to-point which is considered practice.

The command below shows the OSPF details on an interface.

show ip ospf interface

GigabitEthernet0/1 is up, line protocol is up 
  Internet Address 10.1.3.1/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 10.0.0.1, Network Type BROADCAST, Cost: 1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 10.0.0.1, Interface address 10.1.3.1
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:06
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/2/2, flood queue length 0
  Next 0x0(0)/0x0(0)/0x0(0)
  Last flood scan length is 0, maximum is 0
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 0, Adjacent neighbor count is 0 
  Suppress hello for 0 neighbor(s)

To change the type we use the commands below.

configure terminal
interface GigabitEthernet0/0
ip ospf network point-to-point
exit
interface GigabitEthernet0/1
ip ospf network point-to-point

GigabitEthernet0/1 is up, line protocol is up 
  Internet Address 10.1.3.1/24, Area 0, Attached via Network Statement
  Process ID 1, Router ID 10.0.0.1, Network Type POINT_TO_POINT, Cost: 1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Transmit Delay is 1 sec, State POINT_TO_POINT
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:05
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/2/2, flood queue length 0
  Next 0x0(0)/0x0(0)/0x0(0)
  Last flood scan length is 0, maximum is 0
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 0, Adjacent neighbor count is 0 
  Suppress hello for 0 neighbor(s)

Since we enabled debug mode the router will notify us about hello messages sent to neighbours.

*Nov 20 15:37:57.904: OSPF-1 HELLO Gi0/0: Send hello to 224.0.0.5 area 0 from 10.1.2.1
*Nov 20 15:38:02.425: OSPF-1 HELLO Gi0/1: Send hello to 224.0.0.5 area 0 from 10.1.3.1

A full analysis of the Hello Packet can be found on this link.

OSPF Adjacency

*Nov 21 14:00:22.138: %OSPF-5-ADJCHG: Process 1, Nbr 10.0.0.2 on GigabitEthernet0/0 from LOADING to FULL, Loading Done