Vlans
1 Overview of VLANs
VLAN definitions
= provide segmentation and organizational flexibility in switched network
Group of devices within VLAN communicate as if each device was attached to
same cable
VLANs based on logical connections
Each VLAN -> seperate logical network
VLAN creates logical broadcast domain that span multiple physical LAN segments
VLANs improve network performance by separating large broadcast domains in
smaller ones
If device in one VLAN sends broadcast Ethernet frame -> all devices in VLAN
receive frame but devices in other VLANs do not
Benefits of VLAN design
Each VLAN in switched network -> corresponds to IP network
Benefits of designg network with VLANs
Benefit Description
Smaller broadcast Reduces number of devices in broadcast domain
domains
Improved security - Only users in same VLAN can communicate
- Only users in same VLAN can communicate
without router
Improved IT efficiency - VLANs simplify network management
- VLANs can be named
Reduced cost VLANs reduce need for expensive network upgrades
Better performance Smaller broadcast domains reduce unnecessary traffic
on network and improve performance
Types of VLANs
Default VLAN
= VLAN1
, -> default: associated with VLAN1
All ports -> assigned to VLAN1 by default
Native and management VLAN -> VLAN1 by default
VLAN1 -> not renamed or deleted
Data VLAN
= configured to separate user-generated traffic
Reffered to as user VLANs -> separate network in groups of users or devices
Native VLAN
Tagged with VLAN ID when sent to other switch
Trunk ports -> used between switches to support tranmission of tagged traffic
Switch may have tos end untagged traffic across trunk link
Management VLAN
= data VLAN configured specifically for network management traffic including
SSH, telnet, HTTPS, HTTP and SNMP
Defualt: VLAN1
Voice VLAN
= separate VLAN needed to support Voice over IP (VoIP)
VoIP requires:
Bandwidth to ensure voice quality
Transmission priority over other types of network traffic
Ability to be routed around congested areas on network
Delay of less than 150 ms across network
2 VLANs in multi-switched environment
Definition VLAN trunks
VLANs unuseful without VLAN trunks
VLAN trunks = allow all VLAN traffic to propagate between switches (-> enables
devices connected to different switches but in same VLAN to communicate
without going through router)
1 Overview of VLANs
VLAN definitions
= provide segmentation and organizational flexibility in switched network
Group of devices within VLAN communicate as if each device was attached to
same cable
VLANs based on logical connections
Each VLAN -> seperate logical network
VLAN creates logical broadcast domain that span multiple physical LAN segments
VLANs improve network performance by separating large broadcast domains in
smaller ones
If device in one VLAN sends broadcast Ethernet frame -> all devices in VLAN
receive frame but devices in other VLANs do not
Benefits of VLAN design
Each VLAN in switched network -> corresponds to IP network
Benefits of designg network with VLANs
Benefit Description
Smaller broadcast Reduces number of devices in broadcast domain
domains
Improved security - Only users in same VLAN can communicate
- Only users in same VLAN can communicate
without router
Improved IT efficiency - VLANs simplify network management
- VLANs can be named
Reduced cost VLANs reduce need for expensive network upgrades
Better performance Smaller broadcast domains reduce unnecessary traffic
on network and improve performance
Types of VLANs
Default VLAN
= VLAN1
, -> default: associated with VLAN1
All ports -> assigned to VLAN1 by default
Native and management VLAN -> VLAN1 by default
VLAN1 -> not renamed or deleted
Data VLAN
= configured to separate user-generated traffic
Reffered to as user VLANs -> separate network in groups of users or devices
Native VLAN
Tagged with VLAN ID when sent to other switch
Trunk ports -> used between switches to support tranmission of tagged traffic
Switch may have tos end untagged traffic across trunk link
Management VLAN
= data VLAN configured specifically for network management traffic including
SSH, telnet, HTTPS, HTTP and SNMP
Defualt: VLAN1
Voice VLAN
= separate VLAN needed to support Voice over IP (VoIP)
VoIP requires:
Bandwidth to ensure voice quality
Transmission priority over other types of network traffic
Ability to be routed around congested areas on network
Delay of less than 150 ms across network
2 VLANs in multi-switched environment
Definition VLAN trunks
VLANs unuseful without VLAN trunks
VLAN trunks = allow all VLAN traffic to propagate between switches (-> enables
devices connected to different switches but in same VLAN to communicate
without going through router)
