Spanning Tree ProtocolSTP
STP
How does STP work?
STP
STP
Unicast PC0 to PC2 – table Unpopulated
PC0
PC2
PC1
ü
û
PC0
Switches operate as multi-port bridges
Needs a switching table to be populated before filtering is fully functional
Before table is fully populated, how does it work
How does it treat broadcast
© 2007 SSA CATC. All rights reserved
STP
Unicast PC0 to PC2 – table Populated
PC0
PC2
PC1
ü
Switches operate as multi-port bridges
Needs a switching table to be populated before filtering is fully functional
Before table is fully populated, how does it work
How does it treat broadcast
© 2007 SSA CATC. All rights reserved
STP
Broadcast from PC0
Switches operate as multi-port bridges
Needs a switching table to be populated before filtering is fully functional
Before table is fully populated, how does it work
How does it treat broadcast
© 2007 SSA CATC. All rights reserved
STP
© 2007 SSA CATC. All rights reserved
STP
One of the goals of LAN Design = FUNCTIONALITY
(CCNA 3 module 5 page 5.1.1: Functionality - The network must work. The network must allow users to meet their job requirements. The network must provide user-to-user and user-to-application connectivity with reasonable speed and reliability.
RELIABILITY implies REDUNDANCY
The other LAN design goals are: Scalability, Adaptability and Manageability.
© 2007 SSA CATC. All rights reserved
STP
PC0
PC1
PC1
PC1
PC1
PC1
ü
û
û
û
STP
STP
Clearly this design failed on FUNCTIONALITY
Let’s then add some redundancy (4.1STP02)
Clearly this design did not fail on FUNCTIONALITY
© 2007 SSA CATC. All rights reserved
STP
© 2007 SSA CATC. All rights reserved
STP
1. Select Root
Root
X
STP
1. Select Root
STP
1. Select Root
STP
1. Select Root
Cost = 100
Cost = 100
Cost = 100
STP
ROOT
Cost = 100
Cost = 100
Cost = 100
0
0
0
100
STP
ROOT
Cost = 100
Cost = 100
Cost = 100
(RP & DP)
X
DP – every segment, port closets to ROOT
© 2007 SSA CATC. All rights reserved
STP
STP
The STP process (4.1STP04)
STP
STP
Thank you
OUR MISSION