BCMSN LAB - Port Fast

Question:
You work as a network engineer at CiscoSims. The CiscoSims's Chinese office is installing a temporary catalyst 3550 in an IDF to connect 24 additional users. To prevent network corruption, it is important to have the correct configuration prior to connecting to the production network. It will be necessary to ensure the switch does not participate in VTP but forwards VTP advertisements received on trunk ports. All interfaces should transition immediately to the forwarding state of Spanning-Tree due to errors that have been experienced on office computers. Also, configure the user ports (All FastEthernet ports) so that the ports are permanently non·trunking.



The information of the Question:

You will configure FastEthernet ports 0/12 through 0/24 for users who belong to VLAN 20. Also, all VLAN and VTP configurations are to be completed in global conflguration mode as VLAN database mode is being deprecated by Cisco. You are required to accomplish the following tasks:

1. Ensure the switch does not participate In VTP but forwards VTP advertisements received on trunk ports.
2. Ensure all non-trunking interfaces (FaQ/1 to FaQ/24) transition immediately to the forwarding state of Spanning-Tree.
3. Ensure all FastEthernet interfaces are in a permanent non-trunking mode.
4. Place FastEthernet interfaces 0/12 through 0/24 in VLAN 20


Solution:-

switch#conf t

1. To ensure that all FastEthernet interfaces are in a permanent non-trunking mode, put all interfaces in to access mode:-

switch(config)#interface range fa0/1-24
switch(config-if-range)#switchport mode access

2. To ensure that all non-trunking interfaces (FaQ/1 to FaQ/24) transition immediately to the forwarding state of Spanning-Tree, enable port-fast:-

switch(config-if-range)#spanning-tree portfast

3. Place FastEthernet interfaces 0/12 through 0/24 in VLAN 20:-

Note:- We need to use "switchport access vlan 20" command to create vlan 20 as we can not enter in vlan database mode because it is disabled by cisco.

switch(config)#interface range fa0/12 - 24
switch(config-if-range)#switchport access vlan 20
switch(config-if-range)#end

4. To ensure that the switch does not participate In VTP but forwards VTP advertisements received on trunk ports, change vtp mode to transparent:-

switch(config)#vtp mode transparent
switch(config)#exit

5. Save your configuration:-

switch#copy run start


Spanning tree PortFast is a Catalyst feature that causes a switch or trunk port to enter the spanning tree Forwarding state immediately, bypassing the Listening and Learning states. IOS-based switches only use PortFast on access ports connected to end stations. When a device is connected to a port, the port normally enters the spanning tree Listening state. When the Forward Delay timer expires, the port enters the Learning state. When the Forward Delay timer expires a second time, the port is transitioned to the Forwarding or Blocking state. When PortFast is enabled on a switch or trunk port, the port is immediately transitioned to the Forwarding state. As soon as the switch detects the link, the port is transitioned to the Forwarding state (less than 2 seconds after the cable is plugged in).
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