Week 4: VLAN's, VTP, & Port Configurations Flashcards
A VLAN is a single ________ domain
Broadcast
At what OSI layer do switches provide VLAN connectivity?
Layer 2
What is needed to pass data between two PCs that are connected to different VLANs?
A router or a Layer 3 switch
Which Catalyst IOS switch command is used to assign a port to a VLAN?
“switchport access vlan “
What is the Cisco proprietary method for trunk encapsulation?
ISL (Inter-Switch Link)
What protocol dynamically negotiates trunking parameters?
Dynamic Trunk Protocol - DTP
can facilitate the automatic creation of trunks between two switches.
How many different VLANs can an 802.1q trunk support?
4096
Are the native VLAN frames tagged or untagged using ISL?
Tagged (Unlike 802.1Q tagging, there is no concept of a native VLAN in ISL because traffic from all VLANs is encapsulated with a full ISL header)
If two switches each support all types of trunk encapsulation on a link between them, which one would be negotiated?
ISL (When two connected Cisco switches automatically negotiate a trunk with DTP they will choose ISL over 802.1Q unless one switch does not support it or specifically configured not to use ISL)
Which VLANs are allowed on a trunk by default?
All active VLANs
Which command configures a switch port to form a trunk without using negotiation?
“switchport mode trunk”
Two hosts are connected to the same switch, but they can’t communicate with one another. You issue the “show vlan” command and notice that one of the two switch ports is not listed. What might be causing the connectivity issue?
- Both switches are configured in the dynamic auto mode
Define VLAN?
Virtual Local Area Network: used to segment a switch into more than one physical network or broadcast domain.
•They separate L2 Broadcast Domains.
Define Broadcast Domain
A Broadcast Domain consists of all the devices that will receive any broadcast packet originating from any device within the network segment.
Define ISL (Inter-Switch Link)
A Cisco proprietary VLAN tagging protocol. The ISL header is 26 bytes and it appends an additional CRC which is 4 bytes, for a total of 30 additional bytes to every ISL encapsulated frame.
Define 802.1q
Is the network standard that supports VLANs on an Ethernet network. It is a system of tagging for Ethernet frames. • 802.1Q also adds a 4 byte tag into the Ethernet frame for VLAN tagging and is designed exclusively for point-to-point links.
Define DTP
A Cisco proprietary, point-to-point, protocol that negotiates a common trunking mode between two switches.
Define End-to-End VLAN
VLANs spread throughout the network on multiple switches. Follow the 80/20 rule where 80% traffic stays within the same VLAN while 20% is destined for a remote resource out of the workgroup VLAN.
Define Local VLAN
VLANs are kept into the switch block and don’t go beyond the distribution layer. Follow the 20/80 rule where 20% traffic is local, and 80% of the traffic is destined to a remote resource across the core layer.
Define a VLAN trunk
- Allow a switch to send traffic from many VLANs out through a single port
- is a physical path or link in a communications system that is designed to handle many transmissions simultaneously and that interconnects major switching centers or nodes.
- Trunks are used to interconnect switches to form networks, and to interconnect local area networks (LANs) to form wide area networks (WANs) or virtual LANs (VLANs).
Common Terms
VLAN- Virtual Local Area Network, logical identifier for isolating a network
Trunk - A port enabled for VLAN tagging
Access - A port that does not tag and only accepts a single VLAN
Encapsulation - The process of modifying frames of data to include additional information
802.1Q - The most common encapsulation method for VLAN tagging. This is the method used by Meraki devices.
Native VLAN - The VLAN associated with all untagged traffic on a trunk
