CORRECT TEXT
Refer to the Exhibit.
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 configuration 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 (Fa0/1 to Fa0/24) 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
Answer: See the explanation.
Explanation:
switch#conf t
switch(config)#vtp mode transparent
switch(config)#interface range fa0/1 – 24
switch(config-if-range)#switchport mode access
switch(config-if-range)#spanning-tree portfast
switch(config)#interface range fa0/12 – 24
switch(config-if-range)#switchport access vlan 20
switch(config-if-range)#end
switch# copy run startVTP:
The role of the VLAN Trunking Protocol (VTP) is to maintain VLAN configuration consistency
across the entire network. VTP is a messaging protocol that uses Layer 2 trunk frames to manage
the addition, deletion, and renaming of VLANs on a network-wide basis from a centralized switch
that is in the VTP server mode. VTP is responsible for synchronizing VLAN information within a
VTP domain. This reduces the need to configure the same VLAN information on each switch.
VTP minimizes the possible configuration inconsistencies that arise when changes are made.
These inconsistencies can result in security violations, because VLANs can crossconnect when
duplicate names are used. They also could become internally disconnected when they are
mapped from one LAN type to another, for example, Ethernet to ATM LANE ELANs or FDDI
802.10 VLANs. VTP provides a mapping scheme that enables seamless trunking within a network
employing mixed-media technologies.
VTP provides the following benefits:
VLAN configuration consistency across the network
Mapping scheme that allows a VLAN to be trunked over mixed media
Accurate tracking and monitoring of VLANs
Dynamic reporting of added VLANs across the network
Plug-and-play configuration when adding new VLANs
There are three different VTP modes:
1. Server:
By default, a Catalyst switch is in the VTP server mode and in the “no management domain” state
until the switch receives an advertisement for a domain over a trunk link or a VLAN management
domain is configured. A switch that has been put in VTP server mode and had a domain name
specified can create, modify, and delete VLANs. VTP servers can also specify other configuration
parameters such as VTP version and VTP pruning for the entire VTP domain. VTP information is
stored in NVRAM.
VTP servers advertise their VLAN configuration to other switches in the same VTP domain, and
synchronize the VLAN configuration with other switches based on advertisements received over
trunk links. When a change is made to the VLAN configuration on a VTP server, the change is
propagated to all switches in the VTP domain. VTP advertisements are transmitted out all trunk
connections, including ISL, IEEE 802.1Q, IEEE 802.10, and ATM LANE trunks.
2. Client:
The VTP client maintains a full list of all VLANs within the VTP domain, but it does not store the
information in NVRAM. VTP clients behave the same way as VTP servers, but it is not possible to
create, change, or delete VLANs on a VTP client. Any changes made must be received from a
VTP server advertisement.
3. Transparent
VTP transparent switches do not participate in VTP. A VTP transparent switch does not advertise
its VLAN configuration, and does not synchronize its VLAN configuration based on received
advertisements. However, in VTP Version 2, transparent switches do forward VTP advertisements
that the switches receive out their trunk ports. VLANs can be configured on a switch in the VTP
transparent mode, but the information is local to the switch (VLAN information is not propagated to
other switches) and is stored in NVRAM.
To change the VTP mode:
Switch(Config)# vtp mode <Mode>
Or
Switch#vlan database
Switch#vtp <mode>
PortFast
A prime reason for enabling PortFast is in cases where a PC boots in a period less than the 30
seconds it takes a switch to put a port into forwarding mode from disconnected state. Some NICs
do not enable a link until the MAC layer software driver is actually loaded. Most operating systems
try to use the network almost immediately after loading the driver, as in the case of DHCP. This
can create a problem because the 30 seconds of STP delay from listening to Forwarding states
begins right when the IOS begins trying to access the network. In the case of DHCP, the PC will
not obtain a valid IP address from the DHCP server. This problem is common with PC Card
(PCMCIA) NICs used in laptop computers. Additionally, there is a race between operating systems
and CPU manufacturers. CPU manufacturers keep making the chips faster, while at the same
time, operating systems keep slowing down, but the chips are speeding up at a greater rate than
the operating systems are slowing down. As a result, PCs are booting faster than ever. In fact,
modern machines are often finished booting and need to use the network before the STP 30-
second delay is over.
Use the spanning-tree portfast global configuration command to globally enable the PortFast
feature on all non-trunking ports.