What does spanning tree portfast do? (2023)

What does spanning-tree PortFast do?

PortFast causes a switch or trunk port to enter the spanning tree forwarding state immediately, bypassing the listening and learning states.

(Video) Spanning tree PORTFAST Explained | CCNA 200-301
When should spanning-tree PortFast be used?

Portfast is appropriate when you are sure that you are connecting to a single device that will not potentially bridge you to other ports.

(Video) 13. Spanning Tree PortFast
(System Engineer)
What occurs when PortFast?

When PortFast feature is enabled on a switch or a trunk port, the port immediately transitions to the STP forwarding state. Though PortFast is enabled the port still participates in STP. If the port happens to be part of topology that could form a loop, the port eventually transitions into STP blocking mode.

(Video) PortFast + BPDU Guard | STP Optional Features
What are two features of PortFast?

Portfast does two things for us: Interfaces with portfast enabled that come up will go to forwarding mode immediately, the interface will skip the listening and learning state. A switch will never generate a topology change notification for an interface that has portfast enabled.

(Video) PacketTracer - Configure Spanning Tree Protocol, Portfast, and BPDUGuard
Where should the STP PortFast feature be used?

Because the purpose of PortFast is to minimize the time that access ports must wait for STP to converge, it should only be used on access ports. If you enable PortFast on a port connected to a switch, you might create a temporary bridging loop.

(Video) Cisco CCNA Packet Tracer Ultimate labs: Spanning Tree PortFast. Answers
(David Bombal)
What does spanning-tree do?

What is STP and how does it work? Spanning Tree Protocol (STP) is a Layer 2 network protocol used to prevent looping within a network topology. STP was created to avoid the problems that arise when computers exchange data on a local area network (LAN) that contains redundant paths.

(Video) Cisco CCNA Rapid Spanning Tree - PortFast & BPDU Guard (Cisco Packet Tracer)
(Network Direction)
Does PortFast disable spanning-tree?

A common misunderstanding among Cisco students is that portfast disables spanning-tree on a certain interface. This is not correct however…if you enable portfast on an interface then it will jump to the forwarding state of spanning-tree. We still run spanning-tree on the interface!

(Video) STP PortFast | Cisco CCNA 200-301
(Keith Barker - The OG of IT)
Does PortFast port send BPDU?

The port will send out few bpdus at link up, to detect cabling error, and then will stay silent. As soon as a bpdu is received (if any is received), portfast and thus bpdufilter is disabled.

(Video) Cisco Portfast, BPDU Guard, and Root Guard
What is a PortFast port?

PortFast is a Cisco feature for PVST+ environments. When a switch port is configured with PortFast that port transitions from blocking to forwarding state immediately, bypassing the usual 802.1D STP transition states (the listening and learning states).

(Video) How to turn off spanning tree portfast on a Cisco switch port
(Tech Pub)
Which state does the switch port move to when PortFast is enabled?

The portfast feature immediately transitions the port into STP forwarding mode upon link-up.

(Video) Spanning-Tree PortFast Configuration In Packet Tracer | Networking Academy | #PortFast #SpanningTree
(Networking Academy)

What is spanning-tree PortFast and Bpduguard?

The PortFast and BPDU. A BPDU is a data message transmitted across a local area network to detect loops in network topologies. Guard features enhance network reliability, manageability, and security for Layer-2 STP. STP is a network protocol that builds a logical loop-free topology for Ethernet networks. .

(Network Engineer Stuff)
Is PortFast enabled by default?

PortFast and BPDU guard are disabled, by default, on all interfaces.

What does spanning tree portfast do? (2023)
Which is the true statement about STP PortFast mode?

Which is the true statement about STP PortFast mode? The port bypasses the normal STP startup process and enters forwarding mode immediately. Special BPDUs are generated to notify the other switches that the port is an access port and any switches connected to it should cause the port to be disabled.

Can we use spanning PortFast on trunk ports?

The spanning-tree portfast has no effect on trunk ports. If you want to make a trunk port become Forwarding imediately after coming up, you need the spanning-tree porfast trunk command.

Why should you avoid enabling PortFast on a port connected to another switch?

Of course the caveat from Cisco - Caution: Never use the PortFast feature on switch ports that connect to other switches, hubs, or routers. These connections can cause physical loops, and spanning tree must go through the full initialization procedure in these situations.

On which types of ports should you turn on PortFast feature?

PortFast enables the switch to instantaneously transition from blocking state to forwarding state immediately through bypassing the listening and learning state. However, PortFast is highly recommended only on non-trunking access ports, such as edge ports, because these ports typically do not send nor receive BPDU.

How to check PortFast in Cisco?

You can use the "show spanning-tree interface faX/X detail" command. It will show portfast is enabled or disabled.

Do I need spanning-tree PortFast?

PortFast feature should be used only to connect a single workstation to a switch port to avoid layer 2 switching loop. Spanning Tree PortFast feature causes a port to enter the forwarding state immediately, bypassing the listening and learning states.

What does PortFast do Cisco?

Portfast is a Cisco technique that puts a switch interface into forwarding mode immediately, skipping the listening and learning states. This is useful for interfaces that connect to computers or servers so that these devices don't have to wait until the interface is up and running.

Is Portfast enabled by default?

PortFast and BPDU guard are disabled, by default, on all interfaces.

How to check portfast in Cisco?

You can use the "show spanning-tree interface faX/X detail" command. It will show portfast is enabled or disabled.

Should spanning tree be enabled on all ports?

You configure the command “spanning-tree portfast” on all the ports connecting to end devices like workstations. They then automatically bypass the waiting period and DHCP works properly. It's important to only configure this command on ports that connect to end devices though.

How do I set PortFast on spanning tree?

To configure Spanning Tree Protocol (STP) PortFast on a Switch running IOS, run "spanning-tree portfast" command as shown below. To view the configured Spanning Tree PortFast enabled ports, run the "show running-config" IOS command as shown below. We can see that PortFast is enabled on access ports fa0/1 to fa0/24.

How to enable PortFast in Cisco switch?

In switch A, run the following commands as port 20 is connected to a host.
  1. Enter the configuration mode for the interface. ...
  2. Shut down the interface. ...
  3. Change the portfast setting. ...
  4. Review the portfast status. ...
  5. Reset the default spanning tree portfast value for the interface. ...
  6. Review the portfast status.

How does configuring a port with PortFast allow for faster convergence?

How does configuring a port with PortFast allow for faster convergence? PortFast allows for an access port to immediately transition into a forwarding state which decreases Layer 2 convergence time.

You might also like
Popular posts
Latest Posts
Article information

Author: Jamar Nader

Last Updated: 02/11/2023

Views: 5574

Rating: 4.4 / 5 (75 voted)

Reviews: 82% of readers found this page helpful

Author information

Name: Jamar Nader

Birthday: 1995-02-28

Address: Apt. 536 6162 Reichel Greens, Port Zackaryside, CT 22682-9804

Phone: +9958384818317

Job: IT Representative

Hobby: Scrapbooking, Hiking, Hunting, Kite flying, Blacksmithing, Video gaming, Foraging

Introduction: My name is Jamar Nader, I am a fine, shiny, colorful, bright, nice, perfect, curious person who loves writing and wants to share my knowledge and understanding with you.