To avoid loop switches in the network, we use STP (Spanning Tree Protocol) to turn off the traffic on the connection, which is not needed. Loop switch A network system caused by a "broadcast storm" will destroy the network configuration that consumes network bandwidth.
Broadcast storm in the following network, let's say "Computer A" sends a broadcast
When "Computer A" sends a broadcast frame that the switch will forward through all ports. So it will link "SW2" through two links that connect "SW2" with "SW1". When "SW2" disappears, all broadcast frames are out of port. So it will link "SW1" through two links that connect it with "SW2".
We have a broadcast storm
STP will block traffic on one of the two links between "SW1" and "SW2" which will prevent broadcast storms.
BPDU (Bridge Protocol Data Unit): Switches running the STP process send the BPDU frame normally at all times. Made to exchange information with another switch.
Bridge ID (BID): means the combined BID of the priority switch and the MAC address of the switch.
"BID = Priority Switch, MAC address switch" using default switch Priority = 32768, which is equal to 16 x 0 × 8000, the administrator can manually install the priority switch manually using the following command:
Switch (config) # spanning-tree vlan 1 priority Switch priority
Port ID: Every switch port has a port ID, which port ID is combined with the priority port and port number.
"Port ID = port priority.port number" port priority can be a number in the order "0: 255" where default port priority = 128
Link cost: This is the value assigned by each link, depending on the bandwidth (BW).
BW
Cost
10Gbps
2
1Gbps
4
100Mbps
19
10Mbps
100
Root Bridge: is a switch with a low bridge ID (BID) in the network switch.
The root port is the port with the shortest part (least cost path) to the root bridge.
A designated port is a port with the shortest part (least cost path) to the root bridge of all network segments.
17.1 Operation STP To learn STP operation Suppose we have a network like the one below.
In the image above, every switch has a BID written on it, and every link with its BW is written in Mbps.
Below is the operation of STP to remove the link beyond the requirement.
1. Switch with the lowest BID is selected as "Root Bridge" and all ports in this switch are considered "designated ports" as shown below:
2. Each switch selects its "root port", finding the port with the lowest root bridge value as shown below:
3. Port with the smallest cost path to the root bridge in all network segments is selected "designated port" as shown in the figure below:
4. All non-root and non-designated ports are entered in the "blocking state" where it is not forwarded as shown below.
STP has now removed all the excess links already in the network switch. To view STP statistics using the following command
Switch (config) # show spanning-tree
17.2 STP port states The ports in the STP protocol that exist in the following output are blocking state, listening state, learning state, forwarding state.
17.2.1 "Blocking" state In this state, the port does not transmit the frame, it only receives the BPDU.
If the port in the "Blocking state" does not receive the BPDU during the "maximum age time" default of 20 seconds, the port will enter the "listening state".
17.2.2 "listening" state
In this state, the port does not transmit the frame, it receives the BrdU to determine the port role in the STP. port and the remaining "listening state" for "forward delay time" which defaults to 15 seconds and the port will enter the "learning" state
17.2.3 “learning” state
In this state, the port does not send a frame, it receives the BrdU to learn all network paths. The port will remain the "learning state for" forward delay time ", which defaults to 15 seconds, and the port will enter the" forwarding state ".
17.2.4 "forwarding" state
In this port, the port sends and receives all frames. Normally, the STP port can be in the "forwarding state" is an unstable state or in the "forwarding state".
17.3 Fast Port STP is used to set the combined time on the actual port. This is used for network administrators to make sure this port does not define the switch loop profile as in the example causing the port connected to the last device. Fast port STP allows the port to transmit directly from the "blocking state" to the "forwarding state" without going through the "listening state" and "learning state", which reduces transmission time.
17.3.1 Port fast installation
Suppose we have the following network system
The network administrator can install "STP Port fast" on "fa0 / 0" on "SW2" because this port is connected to the last device.
To install "Port fast" we need to use the following command
Switch (config) # interface number
Switch (config) # spanning-tree
17.3.2 Feature introduction to use on ports that can use "STP Port fast"
Protect BPDU guard If BPDU is received on a port that can use "STP Port fast", then the "BPDU guard" enters this port in "error disabled". Because if the BPDU receives on one port, it means that this port is connected to another switch, which port can be in the form of a loop.
Filter the BPDU filter if the BPDU is received on a port that can use "STP Port fast" and the "BPDU filter" captures the port outside of the "STP Port fast".
Because if the BPDU receives on one port this means that this port is connected to another switch and this port can be a loop format.
17.4 “RSTP”, “PVSTP +” and “PVRST +”
17.4.1 “RSTP” (Rapid STP)
RSTP, the "IEEE802.1w" protocol, shortens the speed. This means that a switch running RSTP runs faster than a switch running STP.
RSTP does the following:
It creates an "alternative port" that is considered interchangeable to a "root port" on every switch. Do this to use an alternate port when the "root port" is unknown.
Creating a "backup port" to become a "designated port".
A switch running RSTP can work with a switch running STP. Because RSTP can agree with STP.
RSTP port states
The existing port on the switch running RSTP can be a state like the one below.
Discarding All incoming frames are removed.
Learning does not send the frame, just receives the BPDU to study the network path.
Forward or receive all frames.
RSTP installation
To install RSTP on the switch, we use the following command:
Switch (config) # spanning-tree mode rapid-post
17.4.2 "PVSTP +" (Per-VLAN STP +) Normally, STP integrates into the entire network, only STP occurs one at a time in PVSTP +, every VLAN in the network occurs STP itself.
Suppose we have the following network system:
Using PVSTP +, VLAN1 will have its own STP and VLAN2 will have its own STP
- PVSTP + can be done by default on switches running STP.
- PVSTP + uses "Extended BID" instead of "BID" in STP.
"Extended BID = Switch priority.VLAN ID (VID) .MAC address"
17.4.3 “PVSTP +” (Per-VLAN RSTP +)
In PVSTP + every VLAN in the network has its own RSTP
Suppose we have the following network system
Using PVSTP +, VLAN1 will generate its own RSTP and VLAN2 will generate its own RSTP
Broadcast storm in the following network, let's say "Computer A" sends a broadcast
When "Computer A" sends a broadcast frame that the switch will forward through all ports. So it will link "SW2" through two links that connect "SW2" with "SW1". When "SW2" disappears, all broadcast frames are out of port. So it will link "SW1" through two links that connect it with "SW2".
We have a broadcast storm
STP will block traffic on one of the two links between "SW1" and "SW2" which will prevent broadcast storms.
BPDU (Bridge Protocol Data Unit): Switches running the STP process send the BPDU frame normally at all times. Made to exchange information with another switch.
Bridge ID (BID): means the combined BID of the priority switch and the MAC address of the switch.
"BID = Priority Switch, MAC address switch" using default switch Priority = 32768, which is equal to 16 x 0 × 8000, the administrator can manually install the priority switch manually using the following command:
Switch (config) # spanning-tree vlan 1 priority Switch priority
Port ID: Every switch port has a port ID, which port ID is combined with the priority port and port number.
"Port ID = port priority.port number" port priority can be a number in the order "0: 255" where default port priority = 128
Link cost: This is the value assigned by each link, depending on the bandwidth (BW).
BW
Cost
10Gbps
2
1Gbps
4
100Mbps
19
10Mbps
100
Root Bridge: is a switch with a low bridge ID (BID) in the network switch.
The root port is the port with the shortest part (least cost path) to the root bridge.
A designated port is a port with the shortest part (least cost path) to the root bridge of all network segments.
17.1 Operation STP To learn STP operation Suppose we have a network like the one below.
In the image above, every switch has a BID written on it, and every link with its BW is written in Mbps.
Below is the operation of STP to remove the link beyond the requirement.
1. Switch with the lowest BID is selected as "Root Bridge" and all ports in this switch are considered "designated ports" as shown below:
2. Each switch selects its "root port", finding the port with the lowest root bridge value as shown below:
3. Port with the smallest cost path to the root bridge in all network segments is selected "designated port" as shown in the figure below:
4. All non-root and non-designated ports are entered in the "blocking state" where it is not forwarded as shown below.
STP has now removed all the excess links already in the network switch. To view STP statistics using the following command
Switch (config) # show spanning-tree
17.2 STP port states The ports in the STP protocol that exist in the following output are blocking state, listening state, learning state, forwarding state.
17.2.1 "Blocking" state In this state, the port does not transmit the frame, it only receives the BPDU.
If the port in the "Blocking state" does not receive the BPDU during the "maximum age time" default of 20 seconds, the port will enter the "listening state".
17.2.2 "listening" state
In this state, the port does not transmit the frame, it receives the BrdU to determine the port role in the STP. port and the remaining "listening state" for "forward delay time" which defaults to 15 seconds and the port will enter the "learning" state
17.2.3 “learning” state
In this state, the port does not send a frame, it receives the BrdU to learn all network paths. The port will remain the "learning state for" forward delay time ", which defaults to 15 seconds, and the port will enter the" forwarding state ".
17.2.4 "forwarding" state
In this port, the port sends and receives all frames. Normally, the STP port can be in the "forwarding state" is an unstable state or in the "forwarding state".
17.3 Fast Port STP is used to set the combined time on the actual port. This is used for network administrators to make sure this port does not define the switch loop profile as in the example causing the port connected to the last device. Fast port STP allows the port to transmit directly from the "blocking state" to the "forwarding state" without going through the "listening state" and "learning state", which reduces transmission time.
17.3.1 Port fast installation
Suppose we have the following network system
The network administrator can install "STP Port fast" on "fa0 / 0" on "SW2" because this port is connected to the last device.
To install "Port fast" we need to use the following command
Switch (config) # interface number
Switch (config) # spanning-tree
17.3.2 Feature introduction to use on ports that can use "STP Port fast"
Protect BPDU guard If BPDU is received on a port that can use "STP Port fast", then the "BPDU guard" enters this port in "error disabled". Because if the BPDU receives on one port, it means that this port is connected to another switch, which port can be in the form of a loop.
Filter the BPDU filter if the BPDU is received on a port that can use "STP Port fast" and the "BPDU filter" captures the port outside of the "STP Port fast".
Because if the BPDU receives on one port this means that this port is connected to another switch and this port can be a loop format.
17.4 “RSTP”, “PVSTP +” and “PVRST +”
17.4.1 “RSTP” (Rapid STP)
RSTP, the "IEEE802.1w" protocol, shortens the speed. This means that a switch running RSTP runs faster than a switch running STP.
RSTP does the following:
It creates an "alternative port" that is considered interchangeable to a "root port" on every switch. Do this to use an alternate port when the "root port" is unknown.
Creating a "backup port" to become a "designated port".
A switch running RSTP can work with a switch running STP. Because RSTP can agree with STP.
RSTP port states
The existing port on the switch running RSTP can be a state like the one below.
Discarding All incoming frames are removed.
Learning does not send the frame, just receives the BPDU to study the network path.
Forward or receive all frames.
RSTP installation
To install RSTP on the switch, we use the following command:
Switch (config) # spanning-tree mode rapid-post
17.4.2 "PVSTP +" (Per-VLAN STP +) Normally, STP integrates into the entire network, only STP occurs one at a time in PVSTP +, every VLAN in the network occurs STP itself.
Suppose we have the following network system:
Using PVSTP +, VLAN1 will have its own STP and VLAN2 will have its own STP
- PVSTP + can be done by default on switches running STP.
- PVSTP + uses "Extended BID" instead of "BID" in STP.
"Extended BID = Switch priority.VLAN ID (VID) .MAC address"
17.4.3 “PVSTP +” (Per-VLAN RSTP +)
In PVSTP + every VLAN in the network has its own RSTP
Suppose we have the following network system
Using PVSTP +, VLAN1 will generate its own RSTP and VLAN2 will generate its own RSTP
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