SPANNING TREE (falling of tree)
PER VLAN SPANNING-TREE PLUS(CISCO)
ROOT-BRIDGE FOR EACH & EVERY SINGLE VLAN
MORE CPU OVERHEAD NEEDED
PORT STATES-
DISABLED
BLOCKING
LISTENING
LEARNING
FORWARDING
PORT ROLES-
ROOT
DESIGNATED
BLOCKING
MULTIPLE SPANNING-TREE(802.1S)
ONE INSTANCE FOR A GROUP OF VLANS
UPTO 8 VLANS CAN BE GROUPED UNDER 1 INSTANCE
COMMON SPANNING TREE(802.1D)
ONE ROOT-BRIDGE FOR ALL VLAN
ONE INSTANCE
LESS CPU LOAD
30 SECONDS DELAY FROM BLOCKING TO FORWARDING
PORT STATES-
DISABLED
BLOCKING
LISTENING
LEARNING
FORWARDING
PORT ROLES-
ROOT
DESIGNATED
BLOCKING
RAPID SPANNING-TREE(802.1D)
NO LISTENING STATE
NO LONGER THAN 15 SECONDS IS NEEDED TO GO FROM DISCARDING TO FORWARDING STATE
PORT STATES-
DISCARDING
LEARNING
FORWARDING
PORT ROLES-
ROOT
DESIGNATED
BLOCKING
ALTERNATE
BACKUP
WHY STP???
TO PREVENT LAYER 2 LOOPS
TO MAINTAIN REDUNDANCY
STP CONVERGENCE STEPS:-
ROOT ELECTION
ALL PORTS ARE DESIGNATED PORTS
DESIGNATED PORT ELECTION
ELECTED PER SEGMENT BASIS
ROOT PORT-ELECTION
PORT TO REACH THE ROOT
BLOCKED PORT
ONLY RECIEVE BPDUs IN PVST & CST
CAN RECIEVE & SEND BPDUs IN RSTP
DECISION SEQUENCE IN STP
LOWEST BRIDGE-ID
LOWEST PATH COST
LOWEST SENDER BRIDGE-ID
LOWEST PORT-PRIORITY
LOWEST PORT-ID
STP TERMS
BRIDGE PROTOCOL DATA UNIT(BPDU)
CONFIGURATION BPDUs(AFTER EVERY 2 SEC)
TCN(TOPOLOGY CHANGE NOTIFICATION) BPDU ONLY AFTER TOPOLOGY CHANGE
ROOT BRIDGE
SWITCH HAVING LOWEST BRIDGE-ID
NON-EDGE PORT
PARTICIPATE IN STP ALGORITHM
GENERATES TC(TOPOLOGY CHANGE) BPDUs
BRIDGE-ID
NAME OF SWITCH
PRIORITY(16Bits) + MAC-ADDRESS(48Bits)
DEFAULT PRIORITY 32768
PATH-COST
COST TO REACH THE ROOT
ETHERNET-100
FAST ETHERNET-19
GIGA ETHERNET-4
10 GIGA ETHERNET-2