Switching and VLANs Switching Tasks Switching operation VLANs

Switching and VLANs

Switching Tasks • Switching operation • VLANs • Trunking • Verify VLAN connectivity • Verify spanning-tree operations

Switching operation • Switches forward frames based on destination MAC address • Switches store MAC addresses in the MAC address table • Switches populate the table from the source MAC address from frames that enter the switch • If the destination MAC address is not in the table the switch forwards the frame out all ports in the same VLAN except the receiving port • By default all ports are in VLAN 1

VLAN Overview • Segmentation 3 rd floor • Flexibility 2 nd floor • Security 1 st floor SALES HR ENG A VLAN = A broadcast domain = Logical network (subnet)

VLAN Operations Switch A Red VLAN Black VLAN Green VLAN • Each logical VLAN is like a separate physical bridge

VLAN Operations Switch A Red VLAN Black VLAN Switch B Green VLAN Red VLAN Black VLAN Green VLAN • Each logical VLAN is like a separate physical bridge • VLANs can span across multiple switches

VLAN Operations Switch A Switch B Trunk Fast Ethernet Red VLAN Black VLAN Green VLAN • Each logical VLAN is like a separate physical bridge • VLANs can span across multiple switches • Trunks carries traffic for multiple VLANs

802. 1 q Tagging • Not intrusive to client stations, client does not see the 8 -2. q header VLAN Tag added by outgoing port VLAN Tag stripped by forwarding port 802. 1 q carries VLAN identifier • Effective between switches, routers and switches, switches and servers with 802. 1 q network interface cards

802. 1 Q Frame

VLAN Configuration Guidelines • Maximum number of VLANs is switch-dependent • VLAN 1 is One of the factory default VLANs • Usually there is a one-to-one association between VLANs and subnets

VLAN Configuration Steps • Create VLANs • Assign VLAN to ports • Configure trunks as necessary

Defining a Trunk Many Options… • On = Set trunk on and negotiate with other side Result - Trunk on if other side is on, desirable, or auto • Desirable = Negotiate with other side. Result - Trunk on if other side is on, desirable, or auto • Auto = Will be a trunk only if the other side is on or desirable • Non-negotiate = Set trunk on and will not negotiate

Defining a Trunk • On = Set trunk on and negotiate with other side Result =Trunk on if other side is on, desirable, or auto Switch 1(config-if)# switchport mode trunk

Defining a Trunk • Desirable = Negotiate with other side Result =Trunk on if other side is on, desirable, or auto Switch 1(config-if)# switchport mode dynamic desirable

Defining a Trunk • Auto = Default setting Result =Trunk on if other side is on or desirable Switch 1(config-if)# switchport mode dynamic auto

Verifying a Trunk wg_sw_a#show interface trunk Switch#sh int trunk Port Mode Encapsulation Status Native vlan Fa 0/1 on 802. 1 q trunking 1 Port Fa 0/1 Vlans allowed on trunk 1 -1005 Port Fa 0/1 Vlans allowed and active in management domain 1, 1002, 1003, 1004, 1005 Port Fa 0/1 Vlans in spanning tree forwarding state and not pruned 1, 1002, 1003, 1004, 1005

Adding a VLAN Switch 1(config)# vlan# Switch 1#conf terminal Enter configuration commands, one per line. End with CNTL/Z Switch 1(config)#vlan 9 Switch 1(config-vlan)# name Accounting VLAN

Verifying a VLAN wg_sw_a#show vlan [vlan#]

Assigning Switch Ports to a VLAN Switch 1(config-if)# switchport access vlan 2