Chapter 4 - VLANs Flashcards
What is a VVID
Voice VLAN ID.
What kind of VLAN is assigned to a host PC that is daisy chained to a Cisco VoIP phone?
Native VLAN aka PVID (Port VLAN ID). These are unique cases in that the access layer switch port is not a trunk but the phone uses 802.1q tagging to identify which traffic is for the VoIP phone, and which is destined for the attached PC.
What is the purpose of assigning an unused VLAN number to the Native VLAN of a interface used as a trunk port?
It forces the switch to tag all frames regardless of where they are going across a trunk link. This prevents VLAN mismatches on a trunk from accidentally allowing traffic from one untagged VLAN into another untagged VLAN.
Switch(config-if)# switchport trunk native vlan 99
Why are Native VLAN mismatches dangerous?
If one end is configured for native VLAN 1 and the other for native VLAN 2, a frame that is sent in VLAN 1 on one side will be received on VLAN 2 on the other.
What does DTP stand for
Dynamic Trunking Protocol - Cisco switches will attempt to negotiate trunk links with other Cisco switches when this is enabled.
How do you disable DTP on a switch?
Use the interface configuration option:
switchport nonegotiate
What this does is it specifies that DTP negotiation packets are not sent out this port. This command is valid only when the interface switch port mode is access or trunk (configured by using the switchport mode access or the switchport mode trunk interface configuration commands).
Of the DTP modes, which is more active than the other: Dynamic Desirable or Dynamic Auto?
Dynamic Desirable will “try harder” to bring up a trunk link. Any remote side ports in either Dynamic Desirable or Dynamic Auto will form a trunk connection.
Will a switch with DTP running form a trunk on a Dynamic Auto to Dynamic Auto link?
No. Dynamic Auto is the more passive DTP mode. This connection will remain an access port.
What happens if two switches are connected with manually configured trunk on one side and access on the other?
The switch will only pass traffic for a single VLAN that the port who is an access port is a member of.
How can you check on the DTP mode of a switch?
show interface ethernet 0/3 switchport
What is an end-to-end VLAN?
The term end-to-end VLAN refers to a single VLAN that is associated with switch ports that are widely dispersed throughout an enterprise network, on multiple switches. A Layer 2 switched campus network carries traffic for this VLAN throughout the network.
What is a Local VLAN design look like (Cisco Enterprise Campus Architecture)?
All users of a set of geographically common switches are grouped into a single VLAN, regardless of the organizational function of those users. Local VLANs are generally confined to a wiring closet. If users move from one location to another in the campus, their connection is changed to the new VLAN at the new physical location. Uses multi-layer switches to route between subnets and geographical boundaries.
How do you configure a voice VLAN on a port for a Cisco VoIP phone?
Switch(config)# interface FastEthernet 0/1
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 10
Switch(config-if)# switchport voice vlan 110
How does an access layer switch uplink to an autonomous AP differ from that of a lightweight AP?
The autonomous AP needs an access port at the access layer since it handles direct communication to the WLAN clients. Lightweight AP’s use trunk links back to a Wireless LAN Controller on the network.
Can you add VLANs to a VTP client switch?
No. Switches in VTP client mode will not accept any “vlan” or “no vlan” commands. All VLAN changes must be made on the switch running in the VTP server role.
