How to Enable PortFast on Cisco Switch in GNS3? – When configuring the Spanning Tree Protocol on redundancy networks, we always configure the interfaces as PortFast that connected to the Cisco Switch of the Server computers or network printers.
How to Enable PortFast on Cisco Switch in GNS3?

How to Enable PortFast on Cisco Switch in GNS3?

PortFast configuration is of great importance when Spanning Tree Protocol is configured. In a redundancy network, we must configure the interfaces as PortFast that the interfaces need not to process for STP Convergence.

For example, a Hosting Server, which must constantly serve in a corporate company, should not suffer a 1-minute loss of connectivity. If you are using the Cisco Switches in your network environment, for the interfaces that connected Switches must be set to the Forwarding mode directly, excluding the STP Convergence process.

In the above example, if PortFast is not configured, the server will time out for 50 seconds. In other words, this will not be acceptable for the customers of the company.

In the previous article, we have discussed Examining Spanning Tree Protocol in GNS3 and How to Set Root Bridge on Cisco Switches in GNS3. In this article, we will enable PortFast on the interfaces that are connected by the most important computers.

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How to Enable PortFast in GNS3?

Using the GNS3 program, we will examine the PortFast configuration on Cisco Switches in a small network. Follow the steps below in order.

   Step 1

Open the GNS3 program and create a new project.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 2

If you have not previously added a Layer 2 Switch to the GNS3 program, you can do from the article called How to Add Layer 2 Switch in GNS3. After adding a Layer 2 Switch, create a network topology as shown in the following image.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 3

The following network topology uses VPCS computers. Open the CLI command prompt for VPCS computers and configure the TCP/IP configuration.

Then, test the connection by pinging from the Lenovo PC to HP PC. Add -t at the end of the command to ping continuously.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 4

Remove the cable connected to the L2-SW-1 GigabitEthernet 0/2 interface while Pinging from Lenovo PC to HP PC. Then go back to the CLI command prompt and check the ping.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 5

Naturally, Ping operation between VPCS computers has failed. Now, connect the HP PC to SW1 again and check the status next time.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 6

When the HP PC is reconnected, the SW1 Gig0/2 interface does not go directly to Forwarding Mode as shown in the ping operation. So the downtime will be 50 seconds.

To prevent this situation, we need to configure PortFast on Cisco Switches. And this will result in the 50-second downtime to 1 second!

How to Enable PortFast on Cisco Switch in GNS3?

   Step 7

In the process to enable PortFast on Cisco Switch in GNS3, open the SW1 CLI command prompt and enable PortFast on the interface where the HP PC is connected to the Cisco Switch SW1.

[code] SW1# conf t
SW1(config)# interface gigabitethernet 0/2
SW1(config-if)# spanning-tree portfast
SW1(config-if)# end
[/code]

How to Enable PortFast on Cisco Switch in GNS3?

   Step 8

Start the Ping process again from the Lenovo PC to the HP PC.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 9

In the same way, terminate the SW1 connection with HP PC again.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 10

The ping timeout started when the cable removed.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 11

When we reconnect the HP PC and SW1, the Ping Timeout time will not be the same as it was before PortFast configured. And as a result, it will immediately enter Forwarding mode.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 12

When we check the Ping from the Lenovo PC to the HP PC, we can see that the ping process delay by 1 second.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 13

Apply the show spanning-tree command on Cisco Switch SW1 privileged mode. SW1 You can see that the GigabitEthernet 0/2 interface is Edge.

How to Enable PortFast on Cisco Switch in GNS3?

   Step 14

Likewise, when running the show running-config command on SW1, you can only see that PortFast is enabled on the GigabitEthernet 0/2 interface.

How to Enable PortFast on Cisco Switch in GNS3?

Show Commands Related to How to Enable PortFast in GNS3

SW1#show spanning-treeSW1#show spanning-tree detailSW1#show running-config
SW1#show spanning-tree

VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 005e.5706.1000
Cost 4
Port 2 (GigabitEthernet0/1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 005e.5773.a200
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
——————- —- — ——— ——– ——————————–
Gi0/0 Altn BLK 4 128.1 Shr
Gi0/1 Root FWD 4 128.2 Shr
Gi0/2 Desg FWD 4 128.3 Shr Edge
Gi0/3 Desg FWD 4 128.4 Shr

SW1#

SW1#show spanning-tree detail

VLAN0001 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, sysid 1, address 005e.5773.a200
Configured hello time 2, max age 20, forward delay 15
Current root has priority 32769, address 005e.5706.1000
Root port is 2 (GigabitEthernet0/1), cost of root path is 4
Topology change flag not set, detected flag not set
Number of topology changes 2 last change occurred 00:08:40 ago
from GigabitEthernet0/2
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0, aging 300

Port 1 (GigabitEthernet0/0) of VLAN0001 is alternate blocking
Port path cost 4, Port priority 128, Port Identifier 128.1.
Designated root has priority 32769, address 005e.5706.1000
Designated bridge has priority 32769, address 005e.570d.0b00
Designated port id is 128.1, designated path cost 4
Timers: message age 2, forward delay 0, hold 0
Number of transitions to forwarding state: 0
Link type is shared by default
BPDU: sent 1, received 277

Port 2 (GigabitEthernet0/1) of VLAN0001 is root forwarding
Port path cost 4, Port priority 128, Port Identifier 128.2.
Designated root has priority 32769, address 005e.5706.1000
Designated bridge has priority 32769, address 005e.5706.1000
Designated port id is 128.2, designated path cost 0
Timers: message age 1, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is shared by default
BPDU: sent 3, received 276

Port 3 (GigabitEthernet0/2) of VLAN0001 is designated forwarding
Port path cost 4, Port priority 128, Port Identifier 128.3.
Designated root has priority 32769, address 005e.5706.1000
Designated bridge has priority 32769, address 005e.5773.a200
Designated port id is 128.3, designated path cost 4
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
The port is in the portfast mode
Link type is shared by default
BPDU: sent 276, received 0

Port 4 (GigabitEthernet0/3) of VLAN0001 is designated forwarding
Port path cost 4, Port priority 128, Port Identifier 128.4.
Designated root has priority 32769, address 005e.5706.1000
Designated bridge has priority 32769, address 005e.5773.a200
Designated port id is 128.4, designated path cost 4
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is shared by default
BPDU: sent 276, received 0

SW1#

SW1#show running-config
Building configuration…

Current configuration : 4751 bytes
!
! Last configuration change at 03:47:28 UTC Sat Sep 9 2017
!
version 15.0
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
service compress-config
!
hostname SW1
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
ip cef
no ipv6 cef
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
!
interface GigabitEthernet0/0
media-type rj45
negotiation auto
!
interface GigabitEthernet0/1
media-type rj45
negotiation auto
!
interface GigabitEthernet0/2
media-type rj45
negotiation auto
spanning-tree portfast
!
interface GigabitEthernet0/3
media-type rj45
negotiation auto
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
!
control-plane
!
line con 0
line aux 0
line vty 0 4
!
!
end

SW1#

How to Enable PortFast on Cisco Switch in GNS3? ⇒ Video

You can watch how to enable PortFast on Cisco Switch in GNS3 and you can also subscribe to our YouTube channel…

  Final Word

How to Enable PortFast on Cisco Switch in GNS3? – PortFast is a feature specific to Cisco switches and is not use in other brands. Configuring PortFast is to ensure that the connection on the network is continuous. Spanning Tree PortFast configuration can also implement in the Cisco Packet Tracer program, but it does not support UplinkFast and BackboneFast features.

If this article is helpful, send me feedback by commenting! Thanks in advance, take care of yourself!

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