Categories: All - convergence - roles - cpu - states

by ABHISHEK KUMAR 12 years ago

389

ospf tech

The text discusses various spanning tree protocols used in network management, highlighting their distinct features and operational mechanisms. These protocols, including the Common Spanning Tree (

ospf tech

STP TERMS

EDGE PORT

PATH-COST

ETHERNET-100 FAST ETHERNET-19 GIGA ETHERNET-4 10 GIGA ETHERNET-2
COST TO REACH THE ROOT

ETHERNET-100

FAST ETHERNET-19

GIGA ETHERNET-4

10 GIGA ETHERNET-2

BRIDGE-ID

DEFAULT PRIORITY 32768
PRIORITY(16Bits) + MAC-ADDRESS(48Bits)
NAME OF SWITCH

NON-EDGE PORT

GENERATES TC(TOPOLOGY CHANGE) BPDUs
PARTICIPATE IN STP ALGORITHM

ROOT BRIDGE

SWITCH HAVING LOWEST BRIDGE-ID

BRIDGE PROTOCOL DATA UNIT(BPDU)

TCN(TOPOLOGY CHANGE NOTIFICATION) BPDU ONLY AFTER TOPOLOGY CHANGE
CONFIGURATION BPDUs(AFTER EVERY 2 SEC)

DECISION SEQUENCE IN STP

LOWEST BRIDGE-ID

LOWEST PATH COST
LOWEST SENDER BRIDGE-ID

LOWEST PORT-PRIORITY

LOWEST PORT-ID

STP CONVERGENCE STEPS:-

BLOCKED PORT

CAN RECIEVE & SEND BPDUs IN RSTP
ONLY RECIEVE BPDUs IN PVST & CST

ROOT PORT-ELECTION

PORT TO REACH THE ROOT

DESIGNATED PORT ELECTION

ELECTED PER SEGMENT BASIS

ROOT ELECTION

ALL PORTS ARE DESIGNATED PORTS

WHY STP???

TO MAINTAIN REDUNDANCY

TO PREVENT LAYER 2 LOOPS

SPANNING TREE (falling of tree)

RAPID SPANNING-TREE(802.1D)

PORT STATES-


DISCARDING

LEARNING

FORWARDING


PORT ROLES-


ROOT

DESIGNATED

BLOCKING

ALTERNATE

BACKUP




PORT ROLES- ROOT DESIGNATED BLOCKING ALTERNATE BACKUP
PORT STATES- DISCARDING LEARNING FORWARDING
NO LONGER THAN 15 SECONDS IS NEEDED TO GO FROM DISCARDING TO FORWARDING STATE
NO LISTENING STATE

COMMON SPANNING TREE(802.1D)

30 SECONDS DELAY FROM BLOCKING TO FORWARDING
LESS CPU LOAD
ONE INSTANCE
ONE ROOT-BRIDGE FOR ALL VLAN

MULTIPLE SPANNING-TREE(802.1S)

UPTO 8 VLANS CAN BE GROUPED UNDER 1 INSTANCE
ONE INSTANCE FOR A GROUP OF VLANS

PER VLAN SPANNING-TREE PLUS(CISCO)

PORT STATES-


DISABLED

BLOCKING

LISTENING

LEARNING

FORWARDING


PORT ROLES-


ROOT

DESIGNATED

BLOCKING

PORT ROLES- ROOT DESIGNATED BLOCKING
PORT STATES- DISABLED BLOCKING LISTENING LEARNING FORWARDING
MORE CPU OVERHEAD NEEDED
ROOT-BRIDGE FOR EACH & EVERY SINGLE VLAN