Sample Configuration for Testing OSPF Planned Graceful Restart

During a planned restart, the restarting router informs the neighbors before restarting. The neighbors act as if the router is still within the network topology and continue forwarding traffic to the restarting router. A grace period is set to specify the time period till which the neighbors should consider the restarting router as part of the topology.

The prerequisite configuration mentioned in section 3.2 Configuration Guidelines (Prerequisite) should be done in the switches ISS1, ISS2, ISS3, ISS4, and ISS8 before configuring OSPF.

Figure 1. Topology for Testing OSPF Planned Graceful Restart

Configurations in ISS1:

Execute the following commands.
Type the following:
- Enter the Global Configuration Mode in ISS1.
```
iS5comm# configure terminal
```
- Enable OSPF globally in the switch and enter the Router Configuration mode.
```
iS5comm(config)# router ospf
```
- Configure the OSPF router ID.
```
iS5comm (config-router)# router-id 10.10.2.1
```
- Configure the OSPF interfaces.
```
iS5comm (config-router)# network 10.4.0.1 area 0.0.0.0
```
- Enable opaque functionality in ISS1.
```
iS5comm (config-router)# capability opaque
```
- Enable graceful restart support in ISS1. This configuration enables ISS1 to support planned restart.
```
iS5comm (config-router)# nsf ietf restart-support plannedOnly
```
- Configure the graceful restart timeout interval as 50 seconds in ISS1.
```
iS5comm (config-router)# nsf ietf restart-interval 50
```
- Configure the Grace-LSA Ack required state as enabled in ISS1.
```
iS5comm (config-router)# nsf ietf grace lsa ack required
```
- Configure the Grace LSA retransmission count as 100 in ISS1.
```
iS5comm (config-router)# nsf ietf grlsa retrans count 100
```
- Exit the Router Configuration Mode.
```
iS5comm (config-router)# end
```

View the Configuration done in ISS1.

Type the following:

iS5comm# show ip ospf

OSPF Router with ID (10.10.2.1) (Vrf  default)

Supports only single TOS(TOS0) route

ABR Type supported is Standard ABR

It is an Area Border Router

Number of Areas in this router is 2

Area is 0.0.0.6

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Area is 0.0.0.0

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Planned Non-Stop Forwarding enabled

Restart-interval limit: 50

Grace LSA Retransmission Count: 100

Helper Grace LSA ACK :Required

Restart Reason is:

Unknown

Helper is Giving Support for:

Unknown

Software Restart

Software Reload/Upgrade

Switch To Redundant

Helper Grace Time Limit: 0

Strict LSA checking State Is:Disabled

Route calculation staggering is enabled

Route calculation staggering interval is  10 seconds

Configurations in ISS2

Execute the following commands.
Type the following:
- Enter the Global Configuration Mode in ISS2.
```
iS5comm# configure terminal
```
- Enable OSPF globally in the switch and enter the Router Configuration mode.
```
iS5comm(config)# router ospf
```
- Configure the OSPF router ID.
```
iS5comm (config-router)# router-id 10.10.2.2
```
- Configure the OSPF interfaces.
```
iS5comm (config-router)# network 10.4.0.2 area 0.0.0.0
```
- Exit the Router Configuration Mode.
```
iS5comm (config-router)# end
```

View the Configuration done in ISS2. Also check, if by default ISS2 is providing helper support for all four type of restart reasons.

Type the following:

iS5comm# show ip ospf

OSPF Router with ID (10.10.2.2) (Vrf  default)

Supports only single TOS(TOS0) route

ABR Type supported is Standard ABR

It is an Area Border Router

Number of Areas in this router is 2

Area is 0.0.0.6

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Area is 0.0.0.0

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Planned Non-Stop Forwarding enabled

Restart-interval limit: 50

Grace LSA Retransmission Count: 100

Helper Grace LSA ACK :Required

Restart Reason is:

Unknown

Helper is Giving Support for:

Unknown

Software Restart

Software Reload/Upgrade

Switch To Redundant

Helper Grace Time Limit: 0

Strict LSA checking State Is:Disabled

Route calculation staggering is enabled

Route calculation staggering interval is  10 seconds

Configurations in ISS3

Execute the following commands.
Type the following:
- Enter the Global Configuration Mode in ISS3.
```
iS5comm# configure terminal
```
- Enable OSPF globally in the switch and enter the Router Configuration mode.
```
iS5comm(config)# router ospf
```
- Configure the OSPF router ID.
```
iS5comm (config-router)# router-id 10.1.1.3
```
- Configure the OSPF interfaces.
```
iS5comm (config-router)# network 10.4.0.3 area 0.0.0.0
```
- Exit the Router Configuration Mode.
```
iS5comm (config-router)# end
```

View the configuration done in ISS3. Also check, if by default ISS3 is providing helper support for all four type of restart reasons.

Type the following:

iS5comm# show ip ospf

OSPF Router with ID (10.1.1.3) (Vrf  default)

Supports only single TOS(TOS0) route

ABR Type supported is Standard ABR

It is an Area Border Router

Number of Areas in this router is 2

Area is 0.0.0.6

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Area is 0.0.0.0

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Planned Non-Stop Forwarding enabled

Restart-interval limit: 50

Grace LSA Retransmission Count: 100

Helper Grace LSA ACK :Required

Restart Reason is:

Unknown

Helper is Giving Support for:

Unknown

Software Restart

Software Reload/Upgrade

Switch To Redundant

Helper Grace Time Limit: 0

Strict LSA checking State Is:Disabled

Route calculation staggering is enabled

Route calculation staggering interval is  10 seconds

Configurations in ISS4

Execute the following commands.
Type the following:
- Enter the Global Configuration Mode in ISS4.
```
iS5comm# configure terminal
```
- Enable OSPF globally in the switch and enter the Router Configuration mode.
```
iS5comm(config)# router ospf
```
- Configure the OSPF router ID.
```
iS5comm (config-router)# router-id 10.5.5.4
```
- Configure the OSPF interfaces.
```
iS5comm(config-router)# network 10.5.5.4 area 0.0.0.0
```
```
iS5comm(config-router)# network 10.4.0.4 area 0.0.0.0
```
- Exit the Router Configuration Mode.
```
iS5comm (config-router)# end
```

View the Configuration done in ISS3. Also check, if by default ISS3 is providing helper support for all four type of restart reasons.

Type the following:

iS5comm# show ip ospf

OSPF Router with ID (10.5.5.4)(Vrf  default)

Supports only single TOS(TOS0) route

ABR Type supported is Standard ABR

It is an Area Border Router

Number of Areas in this router is 2

Area is 0.0.0.6

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Area is 0.0.0.0

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Planned Non-Stop Forwarding enabled

Restart-interval limit: 50

Grace LSA Retransmission Count: 100

Helper Grace LSA ACK :Required

Restart Reason is:

Unknown

Helper is Giving Support for:

Unknown

Software Restart

Software Reload/Upgrade

Switch To Redundant

Helper Grace Time Limit: 0

Strict LSA checking State Is:Disabled

Route calculation staggering is enabled

Route calculation staggering interval is  10 seconds

Configurations in ISS8

Execute the following commands.
Type the following:
- Enter the Global Configuration Mode in ISS8.
```
iS5comm# configure terminal
```
- Enable OSPF globally in the switch and enter the Router Configuration mode.
```
iS5comm(config)# router ospf
```
- Configure the OSPF router ID.
```
iS5comm (config-router)# router-id 10.10.2.8
```
- Configure the OSPF interfaces.
```
iS5comm(config-router)# network 10.10.2.8 area 0.0.0.6
```
```
iS5comm(config-router)# network 10.10.1.8 area 0.0.0.6
```
- Exit the Router Configuration Mode.
```
iS5comm (config-router)# end
```

View the configuration done in ISS8. Also check, if by default ISS8 is providing helper support for all four type of restart reasons.

Type the following:

iS5comm# show ip ospf

OSPF Router with ID (10.10.2.8) (Vrf  default)

Supports only single TOS(TOS0) route

ABR Type supported is Standard ABR

It is an Area Border Router

Number of Areas in this router is 2

Area is 0.0.0.6

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Area is 0.0.0.0

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Planned Non-Stop Forwarding enabled

Restart-interval limit: 50

Grace LSA Retransmission Count: 100

Helper Grace LSA ACK :Required

Restart Reason is:

Unknown

Helper is Giving Support for:

Unknown

Software Restart

Software Reload/Upgrade

Switch To Redundant

Helper Grace Time Limit: 0

Strict LSA checking State Is:Disabled

Route calculation staggering is enabled

Route calculation staggering interval is  10 seconds

Configurations for checking GR functionality

Observe the IP routing Table in ISS4. It should have route to 10.10.2.0 network with next hop as ISS1’s vlan1 interface.

Type the following:

iS5comm# show ip route

Codes: C - connected, S - static, R - rip, B - bgp, O - ospf

Vrf Name:          default

---------

C 10.4.0.0/16 is directly connected, vlan1

C 10.5.5.0/24 is directly connected, vlan4

C 10.5.6.0/24 is directly connected, vlan3

O 10.10.1.0/24 [3] via 10.4.0.1

O 10.10.2.0/24 [2] via 10.4.0.1

Observe the IP routing Table in ISS4. It should have route to 10.10.2.0 network with next hop as ISS1’s vlan1 interface.
Type the following:
```
iS5comm(config)# shutdown ospf
```

View the packets sent on vlan1 interface of ISS1. You can see the Grace-LSA from ISS1 sent on that interface.

Type the following:

Frame 2 (106 bytes on wire, 106 bytes captured)

Arrival Time: Feb 17, 2011 10:05:57.329311000

[Time delta from previous packet: 1.781175000 seconds]

[Time since reference or first frame: 1.781175000 seconds]

Open Shortest Path First

OSPF Header

OSPF Version: 2

Message Type: LS Update (4)

Packet Length: 72Source OSPF Router: 10.10.2.1 (10.10.2.1)

Area ID: 0.0.0.0 (Backbone)

Packet Checksum: 0xaaed [correct]

Auth Type: Null

Auth Data (none)

LS Update Packet

Number of LSAs: 1

LS Type: Opaque LSA, Link-local scope

LS Age: 1 seconds

Options: 0x00 ()

0... .... = DN: DN-bit is NOT set

.0.. .... = O: O-bit is NOT set

..0. .... = DC: Demand circuits are NOT supported

...0 .... = L: The packet does NOT contain LLS data block

.... 0... = NP: Nssa is NOT supported

.... .0.. = MC: NOT multicast capable

.... ..0. = E: NO ExternalRoutingCapability

Link-State Advertisement Type: Opaque LSA, Link-local scope (9)

Link State ID Opaque Type: grace-LSA (3)

Link State ID Opaque ID: 0

Advertising Router: 10.10.2.1 (10.10.2.1)

LS Sequence Number: 0x80000001

LS Checksum: ac31

Length: 44

Unknown LSA Type 3

Observe the IP routing Table in ISS4. It should have route to 10.10.2.0 network with next hop as ISS1’s vlan1 interface.

Type the following:

Open Shortest Path First

OSPF Header

OSPF Version: 2

Message Type: LS Acknowledge (5)

Packet Length: 44

Source OSPF Router: 10.1.1.3 (10.1.1.3)

Area ID: 0.0.0.0 (Backbone)

Packet Checksum: 0xb756 [correct]

Auth Type: Null

Auth Data (none)

LSA Header

LS Age: 1 seconds

Options: 0x00 ()

0... .... = DN: DN-bit is NOT set

.0.. .... = O: O-bit is NOT set

..0. .... = DC: Demand circuits are NOT supported

...0 .... = L: The packet does NOT contain LLS data block

.... 0... = NP: Nssa is NOT supported

.... .0.. = MC: NOT multicast capable

.... ..0. = E: NO ExternalRoutingCapability

Link-State Advertisement Type: Opaque LSA, Link-local scope (9)Link State ID Opaque Type: grace-LSA (3)

Link State ID Opaque ID: 0

Advertising Router: 10.10.2.1 (10.10.2.1)

View the output in ISS1. You can see the value of remaining restart-interval and Restart Reason being changed as Software Restart.

Type the following:

iS5comm# show ip ospf

OSPF Router with ID (10.10.2.8) (Vrf  default)

Supports only single TOS(TOS0) route

ABR Type supported is Standard ABR

It is an Area Border Router

Number of Areas in this router is 1

Area is 0.0.0.6

Number of interfaces in this area is 1

SPF algorithm executed 32 times

Area is 0.0.0.0

Number of interfaces in this area is 1

SPF algorithm executed 9 times

Planned Non-Stop Forwarding enabled

Restart-interval limit: 50

Grace LSA Retransmission Count: 100

Helper Grace LSA ACK :Required

Restart Reason is:

Software Restart

Helper is Giving Support for:

Unknown

Software Restart

Software Reload/Upgrade

Switch To Redundant

Helper Grace Time Limit: 0

Strict LSA checking State Is:Disabled

Route calculation staggering is enabled

Route calculation staggering interval is  10 seconds

Ping ISS8’s VLAN 1 Interface (10.10.2.8) from ISS4. It should be successful.

Type the following:

iS5comm# ping 10.10.2.8

Reply Received From :10.10.2.8, TimeTaken : 60 msecs

Reply Received From :10.10.2.8, TimeTaken : 60 msecs

Reply Received From :10.10.2.8, TimeTaken : 60 msecs

--- 10.10.2.8 Ping Statistics ---

3 Packets Transmitted, 3 Packets Received, 0% Packets Loss

Note:

This shows that ISS1 is still in forwarding path although ISS1’s OSPF module’s state is set to shut down.