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.

When should I enable PortFast?

Any port that is directly connected to an end station cannot create bridging loops. Therefore, the port can rapidly transition to the forwarding state by skipping the learning and listening states. To enable immediate transition into the forwarding state, you can enable the STP portfast feature.

What is spanning-tree PortFast used for?

The PortFast feature is introduced to avoid network connectivity issues. These issues are caused by delays in STP enabled ports moving from blocking-state to forwarding-state after transitioning from the listening and learning states.

Why should PortFast be used and on which ports What does it do?

The PortFast feature is introduced to avoid network connectivity issues. ... STP enabled ports that are connected to devices such as a single switch, workstation, or a server can access the network only after passing all these STP states. Some applications need to connect to the network immediately, else they will timeout.

Where can I use PortFast?

It's generally considered a good idea to have portfast configured on anything facing end-hosts (servers, workstations, printers, standard access points, etc). Don't enable it between switches. The next point is how to deal with the possibility of user-generated loops and rogue switches.

13. Spanning Tree PortFast

18 related questions found

Should you use 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.

When would you use a spanning-tree?

The Spanning Tree Protocol (STP) is a network protocol that builds a loop-free logical topology for Ethernet networks. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them.

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!

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 wait period and DHCP works properly. It's important to only configure this command on ports that connect to end devices though.

When using Portfast which of these devices can cause temporary bridging loops?

Connecting hubs, concentrators, switches, bridges, etc... to this interface when portfast is enabled, can cause temporary bridging loops. Use with CAUTION %Portfast has been configured on FastEthernet0/21 but will only have effect when the interface is in a non-trunking mode.

What is the main outcome of the spanning-tree PortFast command?

Portfast feature causes a switch port to enter the spanning tree forwarding state immediately, bypassing the listening and learning states.

What is the primary effect of the spanning-tree port fast command?

What is the primary effect of the spanning-tree portfast command? A. It immediately enables the port in the listening state.

Is PortFast enabled by default?

PortFast is not enabled by default. With PortFast enabled on a port, you effectively take the port and tell spanning tree not to implement STP on that port.

What benefit does PortFast provide to the ordinary connected user?

You can use PortFast on switch or trunk ports that are connected to a single workstation, switch, or server to allow those devices to connect to the network immediately, instead of waiting for the port to transition from the listening and learning states to the forwarding state.

What is a benefit of PortFast configured on a Cisco switch port?

We all know the big advantage of configuring Portfast, a port configured with Portfast will immediately start transmitting data in the 'forwarding' state bypassing the other spanning-tree states.

What is spanning-tree PortFast edge?

#spanning-tree normal. portfast edge is used to configure a port on which an end device is connected, such as a PC. All ports directly connected to end devices cannot create bridging loops in the network. Therefore, the edge port directly transitions to the forwarding state, and skips the listening and learning stages.

What does Spanning Tree Protocol prevent?

The Spanning Tree Protocol (STP) is a network protocol that is used to eliminate bridge loops in Ethernet LANs. STP prevents network loops and associated network outage by blocking redundant links or paths. The redundant paths can be used to keep the network operational if the primary link fails.

Should I disable RSTP?

Disabling RSTP on a port is not recommended unless the client device connected to the port is incompatible with STP. If RSTP is disabled globally, all ports will have RSTP disabled and cannot have it enabled.

How do I know if a port is spanning tree blocking?

Use the show spanning-tree vlan command on all switches to find out which ports are in blocking or forwarding state and confirm your expected Layer 2 path.

Does PortFast port send BPDU?

Part of the myth is also that portfast enabled ports do not send BPDUs. incrementing. Portfast is definitely enabled. ... BPDUs are still sent on portfast enabled ports.

What is P2P edge?

Edge = It's a port that connects to a non-spanning tree device. P2P = It's a full duplex link that connects to another device (Switch) with spanning tree. Shared = It's an half duplex link that connects to another device (Switch) with spanning tree.

What is Spanning Tree Protocol and why is it used?

Spanning Tree Protocol (STP) is a link management protocol that provides path redundancy while preventing undesirable loops in the network. When it comes to ethernet networks, only one active path can exist between two stations in order for them to function properly. Loops occur in networks for a variety of reasons.

Is Spanning Tree Protocol still used?

Spanning Tree Protocol (STP) is dead, or at least it should be. ... STP still only has one focal point (root) and can only have one forwarding path toward that one device. Yes, we can use technologies like EtherChannel to help hide portions of the topology for STP, but STP does NOT do multipath forwarding!

What is spanning tree with example?

A minimum spanning tree is a special kind of tree that minimizes the lengths (or “weights”) of the edges of the tree. An example is a cable company wanting to lay line to multiple neighborhoods; by minimizing the amount of cable laid, the cable company will save money. A tree has one path joins any two vertices.