Week 7 Flashcards
What is VLSM?
Variable Length Subnet Mask (VLSM) allows subnets to be further subdivided into smaller and smaller groupings until each subnet is about the same size as the necessary IP address space.
What is supernetting?
Supernetting is the opposite of subnetting because it is the technique of combining contiguous networks that all use the same CIDR block into one supernet.
What are the two reasons why supernetting is helpful?
- It reduces the number of routing table entries by combining several entries
- It allows a company to create a single network made up of more than one Class C license.
Why is subnetting in IPv6 simpler than IPv4?
- IPv6 addressing uses no classes
- IPv6 does not use subnet masks
- A single IPv6 subnet can supply over 18 quintillion IPv6 addresses
How are IPv6 addresses divided?
An IPv6 address is commonly written as eight blocks of four hexadecimal characters and divided in the following ways:
- The last four blocks identify the interface
- The first blocks identify the network and serve as the network prefix (aka site prefix or global routing prefix)
- The fourth hexadecimal block in the site prefix can be altered to create subnets
What do VLANs do?
A virtual local area network groups ports on a switch so that some of the local traffic on the switch is forced to go through a router. This limits the traffic to a smaller broadcast domain.
What are the reasons for using VLANs?
Reasons to use VLANs include
- Reduce the cost of networking equipment
- Configure temporary networks
- Isolate connections with heavy or unpredictable traffic patterns
- Identify groups of devices:
- whose data should be given priority handling
- that rely on legacy protocols
- who need special security or network functions
How can a switch be configured to use VLANs?
A managed switch can be configured via a CLI (command-line interface) or a web-based management GUI (VLANs can only be implemented on a managed switch)
Can VLANs exist across many switches?
Yes, VLANs can exist across many switches. If two different VLANs are connected to the same switch, traffic still must go via the router.
What is the 802.1Q Tag?
The 802.1Q tag is a 4 byte tag that is added to the ethernet header by the switch that identifies the VLAN ID and allows the determination of which VLAN the frame should go to. The tag is removed once it reaches its final switch port.
What are the two types of ports on a switch that supports VLANs?
- Access port - connects the switch to a host
- Trunk port - connects the switch to a networking device such as a router or another switch and manages traffic from multiple VLANs
What is a trunk in relation to VLANs?
A trunk is a single physical connection between switches through which VLANs can transmit and receive data
What do trunking protocols do?
Trunking protocols assign and interpret VLAN tags in Ethernet frames (Cisco’s VTP is the most popular trunking protocol)
Are VLANs assigned subnets?
Yes, each VLAN is assigned its own subnet of IP addresses
What are the types of VLAN?
Common types of VLAN include the following:
- Default VLAN - typically preconfigured on a switch and initially includes all switch ports
- Native VLAN - receives all untagged frames
- Data VLAN - carries user generated traffic
- Management VLAN - used to give administrative access to a switch
- Voice VLAN - supports VoIP traffic
