VLANs

  • Definition: Virtual Local Area Network or Virtual LAN
  • VLANs allow a layet 2 switch to be broken into many Broadcast domains
  • control of broadcast, multicast, unicast, and unknown unicast within a Layer 2 device.
  • There are two types:
        * Static
        * Dynamic; configured by a VLAN membership Policy server
  • Normal Range is 1-1005, 
         * 802.1Q Expands this to 4095
                                 * 1 = Default Ethernet VLAN
                                 * 1002/1004 = Default Token Ring VLAN
                                 * 1003/1005 = Defaily FDDI VLAN 
                                 * 1006-4096 = Extended VLANs
  • Creates a CAM table per VLAN
  • Traffic in a VLAN is switched, outside is Layer 3 Routed
  • VLANs should typically exist based on location
  • in IOS Based Switches VLAN information is stored in a flash file called VLAN.dat
  • Native VLAN is VLAN1

End to End VLANs

* User VLANs are based on function
* Locations does not matter
* Difficult to troubleshoot

Local VLANs
* Based on geographical location
* would not extend to  core layer
* 80/20 and 20/80 Rule; 80% internal and 20% External traffic, nowadays networks are usually 20/80

Commands:
Creating VLANs

SW01(config)# vlan 10
SW01(config-vlan)#name MarketingDept

Creating Multiple VLANs

SW01(config)# vlan 10,20,30,40

Changing Native VLANs

if)# Switchport trunk native vlan 10

Assigning to ports

SW01(config)# interface fa0/1
SW01(config-if)# switchport mode access
SW01(config-if)# switchport access vlan 10

Verification Commands:

SW01#sh vlan brief
SW01#sh mac-addres-table dynamic vlan 10

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