Data Link Layer Lesson-4

Data link layer (Spanning tree protocol with virtual local area network)

Spanning tree protocol with virtual local area network(vlan)

Data Link Layer (Spanning tree protocol with virtual local area network-vlan)
Data Link Layer (Spanning tree protocol with virtual local area network-vlan) Lesson-4

CCNA, Data link layer

Spanning tree protocol per virtual local area network

Cisco switches run one spanning tree per one virtual local area network (vlan)

Load balancing: -

Bridge id = 4 bit (id vlan) + 12 bit (priority) + 48 bit (MAC Address)

Default priority for cisco switch is 32768

Spanning tree protocol Enhancement:-

1.Port fast feature:-

When switch powered on spanning tree start sending BPDUs, the PC doesn’t understand BPDUs,

The PC will wait 50 sec for the switch to convert spanning tree unless you use port fast

Immediately transitions the port status from blocking to forwarding (skips spanning tree status)

2. BPDUs guard: - it’s used with port fast features

If someone unplugged a PC and attack the switch at their end , the port will put an error disable Mode or shut down to prevent malicious attack (guard)

Vlan trunking protocol (VTP)works in three modes:-

  1. VTP server mode :- vlan in your switch are stored in a file called vlan.dat , you can modify file.
  2. VTP client mode :- listen to these modification sent by VTP server switch, it’s not allowed to modify vlan.dat file.
  3. VTP transparent mode :- it will relay VTP advertisement in one port out the other but it will not apply modification carried in VTP advertisement to itself , it will not apply server switch demand.

It’s allowed to modify its vlan.dat file.

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