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.

When should you enable Portfast?

The most secure implementation of PortFast is to enable it only on ports that connect end stations to switches. Because PortFast can be enabled on nontrunking ports connecting two switches, spanning tree loops can occur because BPDUs are still being transmitted and received on those ports.

What is Bpdu guard used for?

BPDU Guard feature is used to protect the Layer 2 Spanning Tree Protocol (STP) Topology from BPDU related attacks. BPDU Guard feature must be enabled on a port that should never receive a BPDU from its connected device.

What is the use of 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.

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!

Can we enable PortFast on trunk ports?

It is recommended to enable PortFast only on access port types. However, PortFast can be enabled on the trunk ports by selecting the Trunk check box in the WebUI.

Is PortFast enabled by default?

Portfast can be enabled globally or per port. If you enable it globally it is enabled on all access ports. It is not enabled on trunks unless you configured spanning-tree portfast trunk on the interface.

What are the two protocols used in EtherChannel?

EtherChannel protocols – To form an EtherChannel, there are 2 protocols, port aggregation protocol (PAgP) and link aggregation control protocol (LACP). Port Aggregation Protocol is a Cisco proprietary protocol used to form an EtherChannel.

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.

What is Portfast edge?

Beginning with Cisco IOS Release 12.2(33)SXI, you can specifically configure a spanning tree port as either an edge port, a network port, or a normal port. … STP PortFast causes a Layer 2 LAN port configured as an access port to enter the forwarding state immediately, bypassing the listening and learning states.

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What is Cisco Loopguard?

The loop guard feature checks if a root port or an alternate root port receives BPDUs. If the port is receiving BPDUs, the loop guard feature puts the port into an inconsistent state until it starts receiving BPDUs again.

What is Spanning Tree BPDUGuard disable?

You also can use the spanning-tree bpduguard enable interface configuration command to enable BPDU guard on any STP port without also enabling the Port Fast feature. When the interface receives a BPDU, it is put in the error-disabled state.

What does enabling Portfast on a Switchport do?

Enabling the PortFast feature causes a switch or a trunk port to enter the STP forwarding-state immediately or upon a linkup event, thus bypassing the listening and learning states. The PortFast feature is enabled at a port level, and this port can either be a physical or a logical port.

When should I disable spanning tree?

The most common reason for disabling spanning tree is that the original 802.1D Spanning Tree Protocol (STP) goes through a fairly lengthy wait period from the time a port becomes electrically active to when it starts to pass traffic.

What is BPDU packet?

Acronym for bridge protocol data unit. BPDUs are data messages that are exchanged across the switches within an extended LAN that uses a spanning tree protocol topology. BPDU packets contain information on ports, addresses, priorities and costs and ensure that the data ends up where it was intended to go.

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.

How do I check if Portfast is enabled?

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. To display a detailed summary of interface information, run “show spanning-tree detail” command as shown below.

Is PortFast Cisco proprietary?

Portfast is a Cisco proprietary solution to deal with spanning-tree topology changes. … A switch will never generate a topology change notification for an interface that has portfast enabled.

Which commands can be used to enable Portfast on a switch?

BPDU guard can be enabled on all PortFast-enabled ports by using the spanning-tree portfast bpduguard default global configuration command. Alternatively, BPDU guard can be enabled on a PortFast-enabled port through the use of the spanning-tree bpduguard enable interface configuration command.

What is Spanning Tree Rootguard?

Root guard is an STP feature that is enabled on a port-by-port basis; it prevents a configured port from becoming a root port. Root guard prevents a downstream switch (often misconfigured or rogue) from becoming a root bridge in a topology. … Root guard is enabled with the interface command spanning-tree guard root.

What is Spanning Tree Portfast trunk?

spanning-tree portfast allows the ports to skip the blocking to fowarding states and go immediately to forwarding. The spanning-tree portfast trunk does the same but for trunk connections.

What is spanning tree port type edge trunk?

If you enter the spanning-tree port type edge trunk command, the port is configured as an edge port even in the access mode. spanning-tree port type normal—This command explicitly configures the port as a normal spanning tree port and the immediate transition to the forwarding state is not enabled.

How does spanning tree determine priority?

To verify the bridge priority of a switch, use the show spanning-tree command. In Example 3-4, the priority of the switch has been set to 24,576. Also notice that the switch is designated as the root bridge for the spanning-tree instance.

Does spanning tree slow down the network?

In a Spanning Tree network, half the network bandwidth is shut down or blocking. So 40% of network cost (unused ports and larger switches) is simply wasted and doing nothing. Multiple-Instance Spanning Tree (MSTP) was developed to waste less bandwidth.

Can STP and RSTP be mixed?

It is possible to mix PVST and MST (RSTP requires MST), but it needs some planning, and it can be fragile, as you have discovered. You would probably be better off using the same STP version across all your switches. You could change the STP on the Cisco switches to match the rest of the switches.

What is PAGP and Lacp?

LACP stands for Link Aggregation Control Protocol. While PAGP stands for Port Aggregation Protocol. IEEE Standard. The IEEE standard of LACP is IEEE 802.3ad. Etherchannel.

Can I delete default VLAN if deleted what are the effects?

Unfortunately, the default VLAN 1 is not allowed to be removed. Hi Truyen, … Also please be advised that once you configure the switch port with with “trunk-no-default-native” mode, you will have to re-tag all of your previous VLANs as they are removed anytime you change the switch-port mode.

What is a VLAN in networking?

A virtual LAN (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2). … VLANs allow network administrators to group hosts together even if the hosts are not directly connected to the same network switch.

What is an edge port Cisco?

From one of those what i understand is, The edge port is a portfast with BPDU guard and BPDU filtering which loses its portfast status upon receiving a BPDU.. but the normal stp portfast will remains in the portfast state as long as the portfast is disabled manually.

What does BPDU stand for?

(Bridge Protocol Data Unit) A spanning tree protocol (STP) message unit that describes the attributes of a switch port such as its MAC address, priority and cost to reach. BPDUs enable switches that participate in a spanning tree protocol to gather information about each other.

What is Ethernet channel in Cisco?

EtherChannel is a port link aggregation technology or port-channel architecture used primarily on Cisco switches. It allows grouping of several physical Ethernet links to create one logical Ethernet link for the purpose of providing fault-tolerance and high-speed links between switches, routers and servers.