Configure Trunking Between Switches, WAPs, & Servers
VLAN Trunking Protocol (VTP)
Cisco proprietary protocol to automate the updating of multiple VLAN switches.
vtp mode transparent
Effectively disables VTP
Dynamic Desirable
Initiates negotiation messages and responds to negotiation messages to dynamically choose whether to start using trunking
show vtp status
Lists VTP configuration and status information
Three switches have different VTP modes configured. Switch A VTP mode is Server, switch B VTP mode is Transparent, and switch C VTP mode is Client. What will Switch B and C do with a new revision update from switch A?
Switch B will ignore the revision and pass the update to switch C
When you create a SSID, each one is connected to its own what?
VLAN
private vlan
A special purpose VLAN, designated as either primary or secondary, which can restrict or isolate traffic flow with other private VLANs. Exists within another VLAN
CAPWAP (Control and Provisioning of Wireless Access Points)
A standards-based tunneling protocol that defines communication between a lightweight AP and a wireless LAN controller. A "tunnel" from WAP to WLC
Dynamic Trunking Protocol (DTP)
Allows switches to dynamically negotiate trunk links. Rather aggressive protocol that causes Cisco Switches to have its interfaces constantly ask to be a trunk port.
Auto to Auto modes
Does not Work
Auto to Desirable
Does work
Desirable to Desirable
Does work, but weird
What is the default trunking mode for Cisco switches?
Dynamic Desirable
switchport allowed vlan remove [vlan id]
Interface command that removes a vlan from the list of allowed vlans on the trunk port
switchport voice vlan [vlan-id]
Interface subcommand that defines the voice VLAN on a port, meaning that the switch uses 802.1Q tagging for frames in this VLAN
show interfaces trunk
Lists information about the currently operational trunks (or just for the trunk listed in the command) and the VLANs supported on those trunks.
Is VTP a trunking protocol?
NO!
VTP Client Mode
One of three VTP operational modes for a switch with which switches learn about VLAN numbers and names from other switches, but which does not allow the switch to be directly configured with VLAN information.
VTP transparent mode
One of three VTP operational modes. Switches in transparent mode can configure VLANs, but they do not tell other switches about the changes, and they do not learn about VLAN changes from other switches. Essentially disables VTP
VTP Server Mode
One of three sets of operating characteristics (modes) in VTP. Switches in server mode can configure VLANs, tell other switches about the changes, and learn about VLAN changes from other switches.
dynamic auto
Passively waits to receive trunk negotiation messages, at which point the switch will respond and negotiate whether to use trunking.
Cisco Discovery Protocol (CDP)
Protocol that allows Cisco devices to discover other, directly attached Cisco devices. Switches also use CDP to send voice VLAN information to attached IP phones.
Switched Virtual Interface
Provides basic Layer 3 functions for a switch, which does not have a dedicated physical interface for IP addressing. (SVI)
When you manually configure a port to be a trunk port, what will it still do?
Send DTP packets
What is a fatal flaw of VTP?
Switches will replicate VLAN configurations of neighboring switches without second thought.
What should always match between switches if you want trunking to work?
The Native VLAN
vtp pruning
The VTP feature by which switches dynamically choose interfaces on which to prevent the flooding of frames in certain VLANs, when those frames do not need to go to every switch in the network.
show interfaces [int-ID] switchport
This command will show you in-depth configuration details of the specified switchport. Trunking Mode, Trunking Native Mode, Trunking encapsulation mode, etc.,
What is trunking?
Trunking is a type of link that contains multiple VLAN traffic. The segregation is done by tagging the frames with the VLAN.
Native VLAN
Untagged traffic that arrives on an 802.1Q trunk port is placed on a VLAN designated as the native VLAN.
What is the default native VLAN for all switches?
VLAN 1
Desirable to Manually Trunked
Works
vtp domain name
a name that identifies the VTP domain on a switch. This must match between switches participating in VTP.
vtp mode client
set the switch to vtp client mode from (config)# prompt.
vtp mode server
set the switch to vtp server mode from (config)# prompt.
Which Cisco IOS command is used to display the current trunks and the VLANs supported on them?
show interfaces trunk
What interface command would you use to stop an interface from constantly sending DTP packets to establish a dynamic trunking connection?
switchport nonegotiate
What's the difference between using the vlan 10 and interface vlan 10?
vlan 10 will create a vlan with the id of 10. int vlan 10 will create a switched virtual interface on a router which will route traffic for that vlan. Can be used the same way
