2.1.c Implement and Troubleshoot VLAN Flash Cards

2.1.c Implement and Troubleshoot VLAN Flash Cards


Here are my flash cards for 2.1.c Implement and Troubleshoot VLAN. I am giving these flash cards in TXT and in an ANKI package.

If you don’t have or know what Anki is, it is my favorite , free flash card program:

Here is the Anki package you may import and start using the flash cards right away:

How big is the 802.1Q header/field?
4 Bytes

What 3 fields are in the 802.1q header?
1. 802.1p for class of service/l2 qos
2. DEI/Drop eligible indicator
3. ID: vlan membership

What will a switch do if it receives a frame with a 802.1q header and the switch port is an access port?
The switch will drop the frame.

What 4 port types are available with Cisco switches?

1. access
2. trunk
3. dynamic access
4. voice

How would you configure g0/1 as an access port for vlan 2? How would you verify it?



conf t
int g0/1
switchport mode access
switchport access vlan 2
show int g0/1 switchport

Why would we want to statically configure a port as “switchport mode access” ?
This prevents DTP messages from going out of the port, thus prevents DTP attacks.

What 3 things does the macro “switchport host” do?

1. Sets port mode to access
2. Sets spanning-tree portfast edge
3. Disables channel-group on the port

What file holds the vlan config for a switch?
The vlan.dat file holds the vlan config and some vtp config for a switch.

When decomming a switch and factory resetting it, what must be done to wipe the vlan info?
Manually delete them or delete the vlan.dat file via “delete vlan.dat”

What is true about extended vlans and the vlan.dat file?
Extended vlan information is not stored idn the vlan.dat file

What is the normal vlan range? 1 – 1001

What is the reserved vlan range? What is it for? 1002 – 1005.

This range is reserved for GDDI and token-ring vlans.

What is the extended vlan range? What is true about the vtp mode to use these?
1006 – 4094.

To use this range the switch must be in “vtp mode transparent” or “vtp version 3”

How does the “voice vlan” work?
When an access port is also configured for the voice vlan, CDP wil advertise a voice vlan to the Cisco phone on the other end. This allows the phone to dynamically learn the voice vlan, and also dynamically separate its voice from itself and data traffic from the PC.

What are 4 ways to configure a voice vlan, from best to worst?

1. Switchport voice vlan / using the voice vlan + cdp functionality
2. LLDP-MED (vendor neutral) (still requires trunk)
3. DHCP option for voice vlan
4. Static trunk configuration with static phone configuration

When you enable the voice vlan on an access port, what field is added to the CDP message, what 4 fields contain?
The “VoIP VLAN reply” field is added to the CDP message which contains a type value, length, data, and most importantly , voice vlan.

How can we configure int g0/1 with a data vlan of 1, and a voice vlan of 2?

conf t
int g0/1
switchport mode access
switchport access vlan 1
switchport voice vlan 2
no shut

What 4 options does “switchport voice vlan” offer us, describe each?
1. switchport voice vlan (most common and recommended)

2. switchport voice vlan dot1p
sends a voice vlan of 0 to let the phone know they may send .1p CoS to the switch port for QoS.
3. switchport voice vlan none
Don’t tell the phone about the voice vlan, don’t include the fields in the CDP message, however allow them to use it if configured via another method.
4. switchport voice vlan untagged
Tells the phone via CDP to use a voice vlan of 4095, which is a reserved vlan, thus telling the phone to send all data with no .1q no .1p

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