- Switch 1 has the lowest bridge priority and becomes the root bridge. It initiates the Rapid Spanning Tree Protocol (RSTP) handshake process. - Using RSTP's proposal-agreement handshake, the switches determine the root port, designated ports, and path costs to synchronize port states and roles across the network in a proactive manner. - RSTP allows ports to rapidly transition between discarding, learning, and forwarding states, allowing the network to converge faster than STP by eliminating the listening and learning states.

1. How RSTP Works
Gary Jan

2. RSTP Port Roles
• Port Roles
• Root Port
• Offers the Least Cost path to the root bridge
• Designated Port
• Offers the Least Cost path for the attached LAN to the root bridge
• Alternate Port
• Offers the Secondary Least Cost path to the root bridge
• Backup Port
• Offers the Secondary Least Cost path for the attached LAN to the root bridge
• Edge Port
• Connects to end stations but not switches
• Do not participate in RSTP convergence
• Loose its Edge Port status if BPDUs are received

3. RSTP Port States
• 3 Port States
• Discarding
• Incoming data frames are dropped; no MAC learning
• Receiving and Sending BPDUs only
• Learning
• Incoming data frames are dropped; only MAC learning
• Receiving and Sending BPDUs
• Forwarding
• Incoming data frames are forwarded and MAC learning
• Receiving and Sending BPDUs

4. RSTP BPDU Frame Format

5. How does RSTP work?
Assumption
• Switch 1 has the lowest Root ID
• Switch 3 has the largest Root ID
• Switch 1 just boot up
Convergence
1. Switch 1 thinks it is the Root Bridge and starts the Handshake by sending Proposal BPDU
proposing it is the Root Bridge
2. Switch 2 receives the Proposal and Agrees Switch 1 is the Root Bridge. Before sending
the Agreement BPDU
• Switch 2 sync with all non-edge ports and move them to Discarding State
3. Switch 2 send the Agreement BPDU agreeing Switch 1 is the Root Bridge
4. After sending the Agreement BPDU, the port is moved into Forwarding State
immediately
5. After receiving the Agreement BPDU on Switch 1, the port is moved to Forwarding State
immediately
6. Switch 2 then starts the Handshake process to the attached nodes.
Switch 3
Switch 2
Switch 1
Source: CCNP Self-Study CCNP BCMSN Official Exam
Certification Guide Fourth Edition
1. Proposal
2. Sync!
2. DiscardingX
3. Agreement
4. Forward
5. Forward
6. Proposal
Edge Port
7. Agreement
8. Forward
8. Forward

6. RSTP Port Flowchart
Proposal
BPDU?
Superior
Proposal
BPDU?
Yes
- All None-Edge port moves to
Discarding State
- The sender is the Designated
Bridge having the Designated
Port
- Send an Agreement BPDU
back to the sender
- The port becomes the Root
Port
The Root Port
immediately move
to Forwarding
State
Agreement
BPDU?
This Port is a
Designated Port
Immediately move
to Forwarding
State
Receive
Proposal
BPDU?
Inferior BPDU
Superior BPDU
Receive
Proposal
BPDU?
Inferior BPDU
Superior BPDU
Steady State Steady State
Send Proposal
BPDU
Else
Inferior BPDU
Yes
Yes
Yes
No
All None-Edge
port moves to
Discarding State
Else
The port is not a
RP or DP
Move to
Discarding
Receive
BPDU?
No
Discarding
Learning
Forwarding

7. Why is RSTP faster?
1. Proactive convergence using Handshake
• Neighbors use Proposal/Agreement to determine port states and bridge status
2. Introduction of Edge Port, Alternate Port, and Backup Port
• Edge port do not participate in the convergence process
• Alternate Port immediately turn into forwarding state when Root Port fails
• Backup Port immediately turn into forwarding state when the Designated Port of a LAN segment fails
3. Reduction in Port State
• Discarding -> Learning -> Forwarding
• A port can jump directly from Discarding to Forwarding upon receiving Agreement BPDU (i.e. the port is a Designated Port)
• A port can jump directly from Discarding to Forwarding upon sending Agreement BPDU (i.e. the port is a Root Port)
• Eliminate the need of Forwarding Delay
• A port no longer spend 15 sec on Listening and Learning State
4. Proactive failure re-convergence using Proposal/Agreement
• Failure on a link/port triggers Handshake processes with neighbors and the process propagates throughout the network

8. RSTP Convergence 1/10
Root ID = 4096.A
Msg Type = Proposal
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
A2
Cost= 1
B1
Cost= 1
B2
Cost= 1
C1
Cost= 1
C2
Cost= 1
D1
Cost=1
D2
Cost =1
E1
Cost= 5
E2
Cost= 1
Port Role = Unknown
Root ID = 8192.B
Cost of Path = 0
Bridge ID = 8192.B
Root ID = 8192.C
Cost of Path = 0
Bridge ID = 8192.C
Root ID = 8192.E
Cost of Path = 0
Bridge ID = 8192.E
Root ID = 8192.D
Cost of Path = 0
Bridge ID = 8192.D
Round 1- Synchronization
Cost of Path = 0
Bridge ID = 4096.A
Msg Type = Proposal
Port Role = Unknown
Msg Type = Proposal
Port Role = Unknown
Msg Type = Proposal
Port Role = Unknown
Msg Type = Proposal
Port Role = Unknown

9. RSTP Convergence 2/10
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
A2
Cost= 1
B1
Cost= 1
B2
Cost= 1
C1
Cost= 1
C2
Cost= 1
D1
Cost=1
D2
Cost =1
E1
Cost= 5
E2
Cost= 1
Round 1- Decision
• 4096.A from B1 has Superior BPDU than
me (Smaller Root ID)
• 8192.C from B2 has inferior BPDU than me
(Bigger Root ID)
• I will Agree 4096.A is the Root Bridge and
B1 is the Root Port
• I will Propose on B2 4096.A is the Root
Bridge
• The cost to go to 4096.A via me is $1
• 8192.B from A1 has Inferior BPDU
than me (Bigger Root ID)
• 8192.E from A2 has inferior BPDU
than me (Bigger Root ID)
• I am the Root Bridge
• A1 and A2 are the Designated Port
for their attached LAN
• 4096.A from B1 has Superior BPDU than me
(Smaller Root ID)
• 8192.D from E2 has inferior BPDU than me
(Bigger Root ID)
• I will Agree 4096.A is the Root Bridge and E1 is
the Root Port
• I will Propose on E2 4096.A is the Root Bridge
• The cost to go to 4096.A via me is $5

10. RSTP Convergence 3/10
Root ID = 4096.A
Msg Type = Proposal
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP
B2
Cost= 1
C1
Cost= 1
C2
Cost= 1
D1
Cost=1
D2
Cost =1
E1
Cost= 5
RP
E2
Cost= 1
Port Role = Unknown
Root ID = 4096.A
Cost of Path = 1
Bridge ID = 8192.B
Root ID = 4096.A
Cost of Path = 5
Bridge ID = 8192.E
Round 2- Synchronization
Cost of Path = 0
Bridge ID = 4096.A
Msg Type = Agreement
Port Role = RP
Msg Type = Agreement
Port Role = RP
Root ID = 4096.A
Cost of Path = 1
Bridge ID = 8192.B
Msg Type = Proposal
Port Role = Unknown
Root ID = 4096.A
Cost of Path = 5
Bridge ID = 8192.E
Msg Type = Agreement
Port Role = Unknown
B1 & E1 moves immediately from Discarding to Forwarding state after sending Agreement
A1 & A2 moves immediately from Discarding to Forwarding State after receiving Agreement

11. RSTP Convergence 4/10
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP
B2
Cost= 1
C1
Cost= 1
C2
Cost= 1
D1
Cost=1
D2
Cost =1
E1
Cost= 5
RP
E2
Cost= 1
Round 2- Decision
• 8192.B from C1 has Superior BPDU than
me (Smaller Root ID in BPDU)
• 8192.D from C2 has inferior BPDU than
me (Bigger Root ID in BPDU)
• I will Agree 4096.A is the Root Bridge
and C1 is the Root Port
• I will Propose on C2 4096.A is the Root
Bridge
• The cost to go to 4096.A via me is $2
• 8192.E from D1 has Superior BPDU
than me (Smaller Root ID in BPDU)
• 8192.C from D2 has inferior BPDU
than me (Bigger Root ID in BPDU)
• I will Agree 4096.A is the Root Bridge
and D1 is the Root Port
• I will Propose on D2 4096.A is the
Root Bridge
• The cost to go to 4096.A via me is $6

12. RSTP Convergence 5/10
Root ID = 4096.A
Msg Type = Regular
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP
B2
Cost= 1
DP
C1
Cost= 1
RP
C2
Cost= 1
D1
Cost=1
RP
D2
Cost =1
E1
Cost= 5
RP
E2
Cost= 1
DP
Port Role = DP
Root ID = 4096.A
Cost of Path = 2
Bridge ID = 8192.C
Root ID = 4096.A
Cost of Path = 6
Bridge ID = 8192.D
Round 3- Synchronization
Cost of Path = 0
Bridge ID = 4096.A
Msg Type = Agreement
Port Role = RP
Msg Type = Agreement
Port Role = RP
Root ID = 4096.A
Cost of Path = 2
Bridge ID = 8192.C
Msg Type = Proposal
Port Role = Unknown
Root ID = 4096.A
Cost of Path = 6
Bridge ID = 8192.D
Msg Type = Proposal
Port Role = Unknown
C1 & D1 moves immediately from Discarding to Forwarding state after sending Agreement
B2 & E2 moves immediately from Discarding to Forwarding State after receiving Agreement

13. RSTP Convergence 6/10
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP
B2
Cost= 1
DP
C1
Cost= 1
RP
C2
Cost= 1
D1
Cost=1
RP
D2
Cost =1
E1
Cost= 5
RP
E2
Cost= 1
DP
Round 3- Decision
D1 moves immediately from Forwarding to Discarding state after receiving Proposal on D2
• 8192.D from C2 has Inferior PDU than me
(Same Root ID in BPDU but more Expensive
to the Root)
• I will Propose on C2 4096.A is the Root
Bridge
• The cost to go to 4096.A via me is $2
• 8192.C from D2 has Superior BPDU than
me (Same Root ID in BPDU but less
Expensive to the Root)
• I will Agree on D2 4096.A is the Root
Bridge
• I will Propose on D1 4096.A is the Root
Bridge
• The cost to go to 4096.A via me is $3

14. RSTP Convergence 7/10
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP
B2
Cost= 1
DP
C1
Cost= 1
RP
C2
Cost= 1
DP
D1
Cost=1
D2
Cost =1
RP
E1
Cost= 5
RP
E2
Cost= 1
DP
Root ID = 4096.A
Cost of Path = 3
Bridge ID = 8192D
Round 4- Synchronization
Msg Type = Proposal
Port Role = Unknown
Root ID = 4096.A
Cost of Path = 3
Bridge ID = 8192.D
Msg Type = Agreement
Port Role = RP
C2 & D2 moves immediately from Discarding to Forwarding state after sending Agreement

15. RSTP Convergence 8/10
Root ID = 4096.A
Msg Type = Proposal
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP
B2
Cost= 1
DP
C1
Cost= 1
RP
C2
Cost= 1
DP
D1
Cost=1
D2
Cost =1
RP
E1
Cost= 5
RP
E2
Cost= 1
DP
Port Role = DP
Round 4- Decision
Cost of Path = 0
Bridge ID = 4096.A
E1 moves immediately from Forwarding to Discarding state after receiving Proposal on D2
• 8192.D from E2 has Superior PDU than me
(Same Root ID in BPDU but Less Expensive
to the Root)
• I will Agree on E2 4096.A is the Root Bridge
• E1 is the Alternate Port to the Root Bridge
• The cost to go to 4096.A via me is $4

16. RSTP Convergence 9/10
Root ID = 4096.A
Msg Type = Regular
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP
B2
Cost= 1
DP
C1
Cost= 1
RP
C2
Cost= 1
DP
D1
Cost=1
DP
D2
Cost =1
RP/BP
E1
Cost= 5
E2
Cost= 1
RP
Port Role = DP
Root ID = 4096.A
Cost of Path = 4
Bridge ID = 8192.E
Round 5
Cost of Path = 0
Bridge ID = 4096.A
Msg Type = Regular
Port Role = AP
Root ID = 4096.A
Cost of Path = 4
Bridge ID = 8192.E
Msg Type = Agreement
Port Role = RP

17. RSTP Convergence 10/10
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 40
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP
B2
Cost= 1
DP
C1
Cost= 1
RP
C2
Cost= 1
DP
D1
Cost=1
DP
D2
Cost =1
RP/BP
E1
Cost= 5
AP
E2
Cost= 1
RP
Steady State
X
TRAFFIC DIRECTION

18. RSTP Topology Change 1/9
RSTP Topology Change
• Only Non-Edge ports moving from Blocking to Forwarding state cause topology change
• An Alternate or Backup Port moves to Forwarding state immediately if 2 consecutive Hello Messages are not received on the port
• When a topology change is Detected on a switch
• The switch flushes the MAC table on all Non-Edge Designated and Root ports
• The switch sets up a TC While Timer for all its Non-Edge Designated and Root ports
• The TC While Timer = 2 Hello Interval
• While the TC While Timer is active
• All BPDUs send out on a port will have TC bit set
• If necessary, the switch starts new Proposal/Agreement synchronization with its neighbors
• When a switch Receives a BPDU with the TC bit set
• The switch clears the MAC table on ALL ports, Except the ports that receives the topology change
• The switch sets up a TC While Timer for all its Non-Edge Designated and Root ports
• The TC While Timer = 2 Hello Interval
• While the TC While Timer is active
• All BPDUs send out on a port will have TC bit set
• If necessary, the switch starts new Proposal/Agreement synchronization with its neighbors

19. RSTP Topology Change 2/9
Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 5
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP/BP
B2
Cost= 1
DP
C1
Cost= 1
RP/BP
C2
Cost= 1
DP
D1
Cost=1
RP/BP
D2
Cost =1
BP
E1
Cost= 1
RP
E2
Cost= 1
DP
Assume the Steady State Below
TRAFFIC DIRECTION
Discarding State
Backup Port

20. Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 5
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP/BP
B2
Cost= 1
DP
C1
Cost= 1
RP/BP
C2
Cost= 1
DP
D1
Cost=1
RP/BP
D2
Cost =1
BP
E1
Cost= 1
E2
Cost= 1
RSTP Topology Change 3/9
Scenario 1: Link Break
Round 1
Root ID = 8192.5
Msg Type = Proposal
Port Role = Unknown
Cost of Path = 0
Bridge ID = 8192.5
Topology Change= No
Root ID = 4096.100
Msg Type = Regular
Port Role = DP
Cost of Path = 0
Bridge ID = 4096.100
Topology Change= No
Root ID = 4096.100
Msg Type = Regular
Port Role = Unknown
Cost of Path = 2
Bridge ID = 8192.20
Topology Change= No
LINK CUT

21. Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 5
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP/BP
B2
Cost= 1
DP
C1
Cost= 1
RP/BP
C2
Cost= 1
DP
D1
Cost=1
RP/BP
D2
Cost =1
BP
E1
Cost= 1
E2
Cost= 1
RSTP Topology Change 4/9
Scenario 1: Link Break
Round 1 Decision
X
• I am hearing Superior BPDU on D2 (Smaller Root
Bridge ID)
• D2 will be the Root Port
• I will ignore the Proposal on D1
• I will Propose on D1
• I will immediately move D2 to Forwarding State
• I will clear MAC table on D2
• The next 2 BPDU I sent will have TC= Yes

22. Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 5
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP/BP
B2
Cost= 1
DP
C1
Cost= 1
RP/BP
C2
Cost= 1
DP
D1
Cost=1
D2
Cost =1
RP
E1
Cost= 1
E2
Cost= 1
RSTP Topology Change 5/9
Scenario 1: Link Break
Round 2
X
Root ID = 4096.100
Msg Type = Proposal
Port Role = Unknown
Cost of Path = 3
Bridge ID = 8192.30
Topology Change= Yes
Root ID = 4096.100
Msg Type = Regular
Port Role = RP
Cost of Path = 3
Bridge ID = 8192.30
Topology Change= Yes

23. Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 5
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP/BP
B2
Cost= 1
DP
C1
Cost= 1
RP/BP
C2
Cost= 1
DP
D1
Cost=1
D2
Cost =1
RP
E1
Cost= 1
E2
Cost= 1
RSTP Topology Change 6/9
Scenario 1: Link Break
Round 2 Decision
X
• BPDU from E2 is Superior (Smaller
Root Bridge ID)
• I will Agree with BPDU on E2
• I will put E1 into Discarding State

24. Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 5
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP/BP
B2
Cost= 1
DP
C1
Cost= 1
RP/BP
C2
Cost= 1
DP
D1
Cost=1
DP
D2
Cost =1
RP
E1
Cost= 1
E2
Cost= 1
RP
RSTP Topology Change 7/9
Scenario 1: Link Break
Round 3
X Root ID = 4096.100
Msg Type = Agreement
Port Role = RP
Cost of Path = 4
Bridge ID = 8192.5
Topology Change= Yes
Root ID = 4096.100
Msg Type = Regular
Port Role = RP
Cost of Path = 3
Bridge ID = 8192.30
Topology Change= Yes
Root ID = 4096.100
Msg Type = Regular
Port Role = RP
Cost of Path = 2
Bridge ID = 8192.20
Topology Change= Yes

25. Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 5
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP/BP
B2
Cost= 1
DP
C1
Cost= 1
RP/BP
C2
Cost= 1
DP
D1
Cost=1
DP
D2
Cost =1
RP
E1
Cost= 1
E2
Cost= 1
RP
RSTP Topology Change 8/9
Scenario 1: Link Break
Round 4
X
Root ID = 4096.100
Msg Type = Regular
Port Role = RP
Cost of Path = 3
Bridge ID = 8192.30
Topology Change= No
Root ID = 4096.100
Msg Type = Regular
Port Role = RP
Cost of Path = 2
Bridge ID = 8192.20
Topology Change= Yes
Root ID = 4096.100
Msg Type = Regular
Port Role = RP
Cost of Path = 2
Bridge ID = 8192.10
Topology Change= Yes

26. Switch A
MAC= 100
Bridge Priority= 4096
Switch B
MAC= 10
Bridge Priority= 8192
Switch C
MAC= 20
Bridge Priority= 8192
Switch D
MAC= 30
Bridge Priority= 8192
Switch E
MAC= 5
Bridge Priority= 8192
A1
Cost= 1
DP
A2
Cost= 1
DP
B1
Cost= 1
RP/BP
B2
Cost= 1
DP
C1
Cost= 1
RP/BP
C2
Cost= 1
DP
D1
Cost=1
DP
D2
Cost =1
RP
E1
Cost= 1
E2
Cost= 1
RP
RSTP Topology Change 9/9
Scenario 1: Link Break
Steady State
X
TRAFFIC DIRECTION