Tag Archives: 2.1c

2.1.c Implement and troubleshoot VLAN

2.1.c [iii] Normal, extended VLAN, voice VLAN

Normal-range VLANs are VLANs with VLAN IDs 1 to 1005. If the switch is in VTP server or transparent mode, you can add, modify or remove configurations for VLANs 2 to 1001 in the VLAN database. When a switch is in VTP transparent mode (VTP disabled), you can create extended-range VLANs (in the range 1006 to 4094).

A voice VLAN port is an access port attached to a Cisco IP Phone, configured to use one VLAN for voice traffic and another VLAN for data traffic from a device such as a PC attached to the phone.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 1562-1565).  . Kindle Edition.

2.1.c Implement and troubleshoot VLAN

2.1.c [ii] VLAN database

When the switch is in VTP server or transparent mode, you can configure VLANs in the VLAN database mode. When you configure VLANs in VLAN database mode, the VLAN configuration is saved in the vlan.dat file, not the running-config or startup-config files. To display the VLAN configuration, enter the show running-config vlan CLI.

User-configurable VLANs have unique IDs from 1 to 4094. Database mode supports configuration of IDs from 1 to 1001, but not the extended addresses from 1006 to 4094. To create a VLAN, enter the vlan command with an unused ID. To verify whether a particular ID is in use, enter the show vlan id ID command. To modify a VLAN, enter the vlan command for an existing VLAN.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 1552-1559).  . Kindle Edition.

2.1.c Implement and troubleshoot VLAN

2.1.c [i] Access ports

Ethernet interfaces can be configured either as access ports or a trunk ports . An access port can have only one VLA N configured on the interface hence it can carry traffic for only one VLAN.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 1550-1551).  . Kindle Edition.

 

2.1.c Implement and troubleshoot VLAN

2.1.c [iii] Normal, extended VLAN, voice VLAN

STP

In order to facilitate a loop free topology a root switch is elected as a reference point for the entire tree. This is accomplished by establishing a BID (bridge id) for every switch in the diameter. A bridge ID is an 8 byte construct composed of 2 bytes of priority, and 6 bytes MAC address. Further, the priority is segmented into 4 bits priority and 12 bits extended system id, where the extended system id is the VLAN ID.

 

VLAN0010

Spanning tree enabled protocol rstp

Root ID Priority 32778

Address 0009.b73f.ce80

Cost 12

Port 64 (Port-channel2)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

 

Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)

 

32768 16384 8192 4096 2048 1024 512 256 128 64 32 16 8 4 2 1

 

here is the binary math with the example vlan 10

 

1000 0000 0000 1010

 

32768 + 8 + 2