Unit 1: Network Infrastructure
This will allow you to demonstrate your networking skills, knowledge, and abilities, with a focus on enterprise-level switching, routing, and multicast components that support cross-platform (inter)operability and integration with the most recent software-defined technologies.
Portfast is used to get around the slowdown that happens in the spanning tree when a new device is added to the network. For an interface with port fast turned on, when it finds a protocol up event, it skips the listening and learning spanning tree states and goes straight to the forwarding state.
Even though portfast is turned on, the port still sends and receives BPDUs, & also participates in STP elections. When a BPDU is received by an interface, the interface immediately transitions into a non-portfast state and begins the election process. This can result in the creation of a tiny window in which layer 2 loops can take place. Portfast is only enabled on edge ports, which are ports that connect end hosts to the network, and it is combined with a BPDU guard for the purpose of ensuring security. This is done to prevent this from happening. Although it is possible to enable this function on trunking ports as well, it is recommended that you only utilize this feature on edge ports in order to prevent the formation of layer 2 loops.
Configuration:
Portfast on Edge ports: The following command can be executed on the interface to activate portfast on edge ports:
int e0/0
switchport mode access
spanning-tree portfast edge
A warning notice will be displayed to you stating that this function is only enabled for as long as the port operating mode is access port, and that it is recommended that this feature be utilized only with end hosts throughout its operation. Both of the commands can be executed with a single command, which is as follows:
int e0/0
switchport host
Enabling Portfast on Trunk Links:
Configure the trunk link to allow portfast [membership level=”1,2,3″ show_noaccess=”true”]
int e0/0
switchport trunk encapsulation dot1q
switchport mode trunk
spanning-tree portfast network
It is expected that there would be no warning message displayed in the console this time. [/membership]
