Chapter 3 - VLANS CCNA pot

VLAN overviewlogically networked devices that act as if they are on their own independent network • These VLANs allow the network administrator to implement These VLANs allow the network

Chapter 3 - VLANS

CCNA Exploration 4.0

configuration problems associated with VLANs on switches

in a network topology.

Role of VLANS

into smaller ones with VLANs.

participating in broadcasts and allow devices to be

participating in broadcasts and allow devices to be

separated into functional groupings, such as database

services for an accounting department and high-speed

data transfer for an engineering department.

to manage their specific security and bandwidth needs

to manage their specific security and bandwidth needs

VLAN overview

logically networked devices that act as if they are on their own independent network

• These VLANs allow the network administrator to implement These VLANs allow the network administrator to implement

Without VLANs – No Broadcast Control

• Without VLANs, the ARP Request would be seen by all hosts

• Again consuming unnecessary network bandwidth and host processingAgain, consuming unnecessary network bandwidth and host processing

With VLANs – Broadcast Control

Switch Port: VLAN ID

255.255.255.0 VLAN 1 1 2 3 4 5 6

1 2 1 2 2 1

Port VLAN

y Two Subnets

Benefit of VLANS

VLAN ID

VLAN Tagging

No VLAN Tagging

VLAN Tagging

more than one VLAN.

VLAN Tagging

802.10

• There are two major methods of frame tagging Cisco proprietary Inter

• There are two major methods of frame tagging, Cisco proprietary Switch Link (ISL) and IEEE 802.1Q

Inter-• ISL used to be the most common, but is now being replaced by 802.1Q frame tagging gg g

• Cisco recommends using 802.1Q

• VLAN Tagging and Trunking will be discussed in the next chapter

Types of VLAN

• Data VLAN : A data VLAN is a VLAN that is configured to carry only user-generated traffic.

Types of VLAN

• Default VLAN:

– All switch ports become a member of the default VLAN after the

initial boot up of the switch

H i ll th it h t ti i t i th d f lt VLAN k

– Having all the switch ports participate in the default VLAN makes them all part of the same broadcast domain This allows any device connected to any switch port to communicate with other devices on other switch ports

Types of VLAN

• Management VLAN:

– A management VLAN is any VLAN you configure to access the

management capabilities of a switch

management capabilities of a switch

– VLAN 1 would serve as the management VLAN if you did not

proactively define a unique VLAN to serve as the management

VLAN

VLAN

– You assign the management VLAN an IP address and subnet

mask A switch can be managed via HTTP, Telnet, SSH, or SNMP

Types of VLAN

• Native VLAN :

VLANs (tagged traffic) as well as traffic that does not

Types of VLAN

• Voice VLAN:

– It is easy to appreciate why a separate VLAN is needed to support Voice over IP (VoIP)( )

– VoIP traffic requires:

• Assured bandwidth to ensure voice quality

• Transmission priority over other types of network traffic

• Ability to be routed around congested areas on the network

• Delay of less than 150 milliseconds (ms) across the network

Voice VLAN

Types of traffic

Types of traffic

Types of traffic

Types of traffic

Switch port membership

VLAN Trunk

• Tag control information field

• Tag control information field

– 3 bits of user priority - Used by the 802.1p standard , which specifies how to provide expedited transmission of Layer 2 frames A description of the IEEE 802.1p is beyond the scope of this course; however, you learned a little about it earlier in the discussion

Native Vlan and 802.1q

Trunking mode

• The trunking modes

available in Fast Ethernet

and Gigabit Ethernet

switchport mode trunk

switchport mode access

switchport mode dynamic desirable

switchport mode dynamic auto

Nonegotiate

switchport nonegotiate

Trunking mode

Configure VLAN and Trunking

Assign VLAN to port

Configuring Ranges of VLANs

vlan 3

SydneySwitch(config)#interface range

fastethernet 0/8 - 12 fastethernet 0/8 12 SydneySwitch(config-if)#switchport access vlan 3

SydneySwitch(config-if)#exit

Verify VLAN

Delete Vlan

Configure Trunk link

Common Problem

Naitve VLAN mismatch

Trunk mode mismatch

Incorrect VLAN list

Mistake of VLAN and IP subnets

Summary