Block 2 Chapter 3

STP port state (disabled)

is a state for a switch port where it is administratively shutdown.

Bridge Protocol Data Unit (BPDU)

BPDUs are frames which are sent out by switches that contain relevant information to STP(Spanning Tree Protocol) and are sent out every two seconds by default

Order of STP port states

1.Listening 2.Learning 3.Forwarding

broadcast storm

A breaking point where it is unable to process frames entirely and quickly maxes out its CPU utilization. This has a cascading effect on a computer network as well because with the amount of traffic generated, it also maxes out the bandwidth of neighboring links and CPU for neighboring devices.

Network Loop

A loop on a computer network happens when there is more than one link between two pieces of network equipment that causes repetition of the frames being transmitted between them to literally loop between them infinitely.

designated port (DP)

All ports that are permitted to forward frames on the root bridge are referred to as Designated Ports.

Loop Avoidance

If multiple connections between switches are created for redundancy purposes, network loops can occur. Spanning Tree Protocol (STP) is used to stop network loops while still permitting redundancy.

root port

Ports that are permitted to forward on non-root bridge switches are referred to as Root Ports (because they point towards the root bridge).

Spanning Tree Protocol (STP)

STP (Spanning Tree Protocol) allows for multiple paths to exist between pieces of network equipment on a computer network without the threat of a potential broadcast storm occurring.

CPU (Central Processing Unit)

To process and forward a frame that has been received also requires a certain percentage of the switch's Central Processing Unit (CPU) to accomplish.

Order of Spanning Tree Topology

Top: Root Middle: Designated Bridge Bottom: Root Port Below bottom: Switches

Root Bridge

When the root bridge is selected, all participating switches in the STP topology will choose their best link to the switch selected as the root bridge and place it in a forwarding state. All redundant links will be placed in a blocking state for loop prevention. This election of the root bridge is accomplished via Bridge Protocol Data Units (BPDUs) that are sent out by the switches.

Broadcast frames

frames that have a destination address of FFFF.FFFF.FFFF, are sent out by individual nodes on a computer network when using a variety of different protocols

STP port state: forwarding

is a state for a switch port after the initial listening and learning states have occurred. At this point, a switch port is in normal operation and is both receiving and forwarding frames that contain data from nodes on the computer network. The switch port will also continue to process BPDUs to make determinations on the STP topology that it is connected to.

STP port state (Blocking)

is a state for a switch port where STP(Spanning tree protocol) has determined the possibility of a loop exists should the switch port be allowed to forward frames. To prevent a potential broadcast storm from occurring on a computer network, frames containing data from nodes on the network are neither sent or received by the blocking switch port.

STP Port State: Listening

is a state for a switch port where it will process received BPDUs to decide on the STP( Spanning tree Protocol) topology that it is connected to. It will not populate the MAC address table of the switch and will not forward frames that contain data from nodes on the network.

STP Port State: Learning

is a state for a switchport after the initial listening state has occurred. It will still be unable to forward frames containing data from nodes on the network, however, it will begin to populate the MAC address table with the source MAC address of any frames received on the interface it is assigned to.

Spanning-Tree Topology

the protocol will assign various roles to the active switch ports involved in forwarding traffic between the participating STP(Spanning Tree Protocol) configured switches on a computer network It will assess multiple paths that exist between a switch and another switch and prioritize one switch port involved in that communication path over the other. STP (Spanning Tree Protocol) will allow traffic to flow through the switch ports it designates to be in a Forwarding state while disallowing traffic on switch ports it designates to be in a Blocking state.