How to Configure UplinkFast on Cisco Switch in GNS3 – When we configure the standard Spanning Tree Protocol on Layer 2 Switches, a link failure result STP Convergence takes 50 seconds. We can reduce this downtime to 20 seconds with UplinkFast.
How to Configure UplinkFast on Cisco Switch in GNS3

How to Configure UplinkFast on Cisco Switch in GNS3

As you know Spanning Tree UplinkFast, BackboneFast and PortFast is Cisco specific. Configuring the Spanning Tree Protocol on Layer 2 Switches is to prevent Loops that may occur in the intended network.

Spanning Tree The UplinkFast feature must enable on a Switch with a Blocked Port. The reason we do this is to allow the Blocked Port to immediately enter the Forwarding Mode as a result of a link failure. So the UplinkFast feature will reduce the downtime time by 50 seconds to 20 seconds.

In our previous articles, we discussed how to configure PortFast on Cisco Switch in GNS3 and how to set Root Bridge on Cisco Switch in GNS3. In this our article, we will use examine the UplinkFast configuration on Layer 2 Cisco Switches.

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GNS3 UplinkFast Configuration

You need to add Layer 2 Switch to GNS3 for UplinkFast configuration. Cisco Packet Tracer program does not support features such as UplinkFast and BackboneFast.

For the GNS3 UplinkFast configuration, follow the steps below in order.

   Step 1

Open the GNS3 program and create a new project for the UplinkFast configuration.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 2

In the GNS3 program, create a topology as follows. You also configure TCP/IP for VPCS computers.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 3

Check the Spanning Tree Protocol configuration of the Cisco Switches on the topology, and note the Port States by selecting the Root Bridge Switch.

The Cisco Switch SW1 shows the Root Bridge at the output of the show spanning-tree command.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 4

At the Switch SW2 CLI command prompt, run the show spanning-tree command and note the Port States.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 5

Likewise, note the Cisco Switch SW3 Port States.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 6

Before configuring UplinkFast on Cisco Switch in GNS3, you should initiate continuous Ping from the Lenovo PC to the HP PC.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 7

Remove the cable between SW1 and SW2 while Ping the Lenovo PC from the HP PC continuously.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 8

The STP Convergence process takes 50 seconds. So we can reduce this time by 30 seconds by enabling the STP UplinkFast feature on a Switch with one Blocked Port.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 9

Since Cisco Switch SW2 has one Blocked Port, we will configure UplinkFast on this Switch. Open the Cisco Switch SW2 CLI command prompt and execute the following command to enable UplinkFast on the Switch.

SW2# conf t
SW2(config)# spanning-tree uplinkfast
SW2(config)# end
SW2#

 
How to Configure UplinkFast on Cisco Switch in GNS3

   Step 10

After enabling the UplinkFast feature on the Switch, we can verify that this feature is enabled with the show spanning-tree summary command.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 11

The process to configure UplinkFast on Cisco Switch in GNS3 is very simple. Now, to verify how UplinkFast works, start the continuous Ping process from the Lenovo PC to the HP PC again.

Then remove the cable between SW1 and SW2 again.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 12

STP Convergence has completed in almost 20 seconds. You can better understand the benefits of enabling UplinkFast on the Switch from the image below.

How to Configure UplinkFast on Cisco Switch in GNS3

   Step 13

Finally, when we reconnect the cable between SW1 and SW2, you can see that the ping process continues without interruption.

How to Configure UplinkFast on Cisco Switch in GNS3

Show Commands Related to How to Configure UplinkFast on Cisco Switch in GNS3

SW2#show spanning-tree summarySW2#show spanning-tree detailR1#show running-configR1#show running-configR1#show running-config
SW2#show spanning-tree summary
Switch is in pvst mode
Root bridge for: none
Extended system ID is enabled
Portfast Default is disabled
PortFast BPDU Guard Default is disabled
Portfast BPDU Filter Default is disabled
Loopguard Default is disabled
EtherChannel misconfig guard is enabled
Configured Pathcost method used is short
UplinkFast is enabled
BackboneFast is disabled

Name Blocking Listening Learning Forwarding STP Active
———————- ——– ——— ——– ———- ———-
VLAN0001 1 0 0 3 4
———————- ——– ——— ——– ———- ———-
1 vlan 1 0 0 3 4

Station update rate set to 150 packets/sec.

UplinkFast statistics
———————–
Number of transitions via uplinkFast (all VLANs) : 0
Number of proxy multicast addresses transmitted (all VLANs) : 0
SW2#

SW2#show spanning-tree detail

VLAN0001 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 49152, sysid 1, address 002c.78f0.2f00
Configured hello time 2, max age 20, forward delay 15
Current root has priority 32769, address 002c.785d.8700
Root port is 1 (GigabitEthernet0/0), cost of root path is 3004
Topology change flag not set, detected flag not set
Number of topology changes 3 last change occurred 00:02:02 ago
from GigabitEthernet0/1
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
Uplinkfast enabled

Port 1 (GigabitEthernet0/0) of VLAN0001 is root forwarding
Port path cost 3004, Port priority 128, Port Identifier 128.1.
Designated root has priority 32769, address 002c.785d.8700
Designated bridge has priority 32769, address 002c.785d.8700
Designated port id is 128.1, 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 31, received 272

Port 2 (GigabitEthernet0/1) of VLAN0001 is alternate blocking
Port path cost 3004, Port priority 128, Port Identifier 128.2.
Designated root has priority 32769, address 002c.785d.8700
Designated bridge has priority 32769, address 002c.78f0.1500
Designated port id is 128.2, designated path cost 4
Timers: message age 2, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is shared by default
BPDU: sent 2, received 308

Port 3 (GigabitEthernet0/2) of VLAN0001 is designated forwarding
Port path cost 3004, Port priority 128, Port Identifier 128.3.
Designated root has priority 32769, address 002c.785d.8700
Designated bridge has priority 49153, address 002c.78f0.2f00
Designated port id is 128.3, designated path cost 3004
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is shared by default
BPDU: sent 301, received 0

Port 4 (GigabitEthernet0/3) of VLAN0001 is designated forwarding
Port path cost 3004, Port priority 128, Port Identifier 128.4.
Designated root has priority 32769, address 002c.785d.8700
Designated bridge has priority 49153, address 002c.78f0.2f00
Designated port id is 128.4, designated path cost 3004
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is shared by default
BPDU: sent 301, received 0

SW2#

SW2#
*Sep 12 13:31:34.053: %SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN0001 GigabitEthernet0/1 moved to Forwarding (UplinkFast).
*Sep 12 13:31:52.253: %SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN0001 GigabitEthernet0/0 moved to Forwarding (UplinkFast).
SW2#
SW2#show spanning-tree uplinkfast
UplinkFast is enabled

Station update rate set to 150 packets/sec.

UplinkFast statistics
———————–
Number of transitions via uplinkFast (all VLANs) : 2
Number of proxy multicast addresses transmitted (all VLANs) : 0

Name Interface List
——————– ————————————
VLAN0001 Gi0/0(fwd), Gi0/1
SW2#

SW2#show spanning-tree

VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 002c.785d.8700
Cost 3004
Port 1 (GigabitEthernet0/0)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 49153 (priority 49152 sys-id-ext 1)
Address 002c.78f0.2f00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Uplinkfast enabled

Interface Role Sts Cost Prio.Nbr Type
——————- —- — ——— ——– ——————————–
Gi0/0 Root FWD 3004 128.1 Shr
Gi0/1 Altn BLK 3004 128.2 Shr
Gi0/2 Desg FWD 3004 128.3 Shr
Gi0/3 Desg FWD 3004 128.4 Shr

SW2#

How to Configure UplinkFast on Cisco Switch in GNS3 ⇒ Video

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

  Final Word

How to Configure UplinkFast on Cisco Switch in GNS3 – Configuring Spanning Tree UplinkFast is a very useful operation. If your Cisco Switches do not support Rapid STP, you can enable UplinkFast to improve performance in Standard STP configuration.

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