Video no. 7 (300-115)

Objective of this videos Understanding, configuring and verifying VLAN & trunk.

Troubleshooting and managing VLAN database.

VLAN is layer 2 isolation of traffic (1VLAN=1 broadcast domain=1subnet) for better resource utilization, QOS, logically groups users and security.

VLAN no.: - VLAN no Usage Description 0,4095 Reserved Not show on VLAN database

1,1002-5 Default VLAN Can`t modified/delete, can use only

1006-4094 Extended range VTP modes must be transparent to use extended range of VLAN 2-1001, 1006-4094

Use for Ethernet LAN

Can be used and modified/delete if necessary for Ethernet LAN

Note no. of VLAN also depend on switch model.

Type of VLAN: - Type of VLAN Descriptions Data Use for normal data

Voice/axillary Use for IP phone/Voice over IP

Private Use for security , it divided primary and secondary VLAN Management A VLAN which for Telnet, SSH for configuration

Extended Nothing special but will usable if VTP mode is transparent on switches Native VLAN For backward compatibility, frame are untagged send over trunk link (by default VLAN1)

Note: - On topic of infra security will discuss more for Private VLAN in this series

Host/node assignment on VLAN: - By port basis, port reserve for particular VLAN, manual assignment required every time while assigning to other VLAN By MAC address basic, more efficient utilization, any port can be used for any VLAN (VMPS server required) Note: - A single port can be used for Data and Voice VLAN as well

VLAN creation ways: - 1) On global prompt 2) On VLAN database prompt 3) Directly assign interface to VLAN also create VLAN if not exists

VLAN port Roles: -

Switch port mode Description and works

Access Belong to one VLAN for data can voice as well, not deal with tagged frame until IP phone connected to that port (disable DTP)

Trunk Belong to multiple VLAN, Deal with tagged & untagged frame (DTP can be disable for ISL and .1q tagging, default is enable )

Dynamic auto Negotiation mode to for trunk and access (default role)

Dynamic Desirable Negotiation mode but activity form trunk (available on higher series ) *Single port can be belong two different VLAN one for data other for Voice

Note: - Port Operational mode changes if port is Auto/desirable

Valid mode of port to forming Trunk: - Port role side A Port role side B Result Access Access No trunk form

Access Trunk No trunk form Access Desirable No trunk form

Dynamic auto Dynamic auto No trunk form Desirable Dynamic auto Trunk form

Desirable Desirable Trunk form Desirable Trunk Trunk form

Trunk Dynamic auto Trunk form Trunk Trunk Trunk form

Administrative Mode V/S Operational Mode Configure to work as = Administrative Mode (define by Admin) Currently working as = Operational Mode (select by negotiation) Note: - If port Administrative mode is Auto/dynamic/desirable then it can be work as access or trunk by negotiation

Troubleshooting Trunk port Switch#show interfaces f0/1 switchport Switch#show interfaces trunk

Characteristics of trunk port & access port:-

Trunk port generally use for connect switches and router.

Access port use port connect end device (like Computer, IP Phone, IP camera etc.

Trunk port is member of all VLAN be default.

Access port is member of one data VLAN and voice VLAN if vice VLAN configured.

A trunk link must have same native VLAN on both side.

Trunk port can be allow or deny particular VLAN data.

Trunk encapsulation/tagging: -

.1q ISL IEEE (802.1q) CISCO proprietary

Backward compatible (Native VLAN) No compatibility

Support 4095 no. of VLAN 1000 no. of VLAN

Header size 4 bytes 26 bytes

Trailer size N/A 4 bytes FCS and recalculation required Not required

Dynamic Trunking Protocol (DTP) is a proprietary networking protocol developed

by Cisco Systems for the purpose of negotiating trunking on a link between two VLAN-aware switches, and for negotiating the type of trunking encapsulation to be used. It works on the Layer 2 of the OSI model. VLAN trunks formed using DTP may utilize

either IEEE 802.1Q or Cisco ISL trunking protocols.

Managing VLAN database and troubleshooting: - Removing VLAN

Unassigned port from VLAN /Default mode

Deleting VLAN database Problem) why port not shown while executed command SW1# show vlan

Solution: - Port may trunk or assign to deleted/removed VLAN from database Problem) why VLAN automatic created after power recycle, even after deleted from database & flash: Solution: - Port may assign to VLAN so after rebooting switch find startup configuration with VLAN that not exist will create automatically These notes takes from CISCO/Wikipedia.org website then edited for this video

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