add STP toolkit Part 2 BPDU

21. Protocole Spanning Tree (part2).md

@@ -103,8 +103,123 @@ from the blocking state to the listening state (15 seconds), learning state (15
 and then finally the forwarding state. So it can take a total of 50 seconds for a blocking
 interface to transition to forwarding
 
+- These timers and transitional states are to make sure that loops aren't accidentally created
+by interface moving to forwarding state too soon.
+
+      note: A forwarding interface can move directly to a blocking state (there is no worry
+      about creating a loop by blocking an interface).
+      A blocking interface cannot move directly to forwarding state, it must go through the
+      listening and learning states.
+
+```Wireshark
+Dst: PVST+ (01:00:0c:cc:cc:cd)
+```
+
+PVST = Only ISL trunk enquapsulation
+PVST+ = Supports [[802.1Q]]
+
+Regular STP (not Cisco's PVST+)
+uses a destination MAC address of 0180.c200.0000
+
+The STP timers on the root bridge determine the STP timers for th entire network.
+
+## Spanning Tree Optional Features (STP Toolkit)
+
+### Portfast
+
+Portfast allows a port to move imediately to the Forwarding state, 
+bypassing *Listening* and *Learning*.
+
+If used, it must be enabled *only on ports connected to end hosts,*
+if enabled on a port connected to another switch it could cause a Layer 2 loop.
+
+```Cisco
+SW1(config)#interface g0/2
+SW1(config-if)#spanning-tree portfast
+```
+
+You can also enable portfast with the  command:
+
+```Cisco
+SW1(config)#spanning-tree portfast default
+```
+
+This enables portfast on all access ports (not trunk ports).
+
+### BPDU Guard
+
+if an interface with BPDU Guard enabled receives a BPDU from another switch,
+the interface will be shut down to prevent a loop from forming.
+
+```Cisco
+SW1(config)#interface g0/2
+SW1(config-if)#spanning-tree bpduguard enable
+```
+
+You can also enable portfast with the  command:
+
+```Cisco
+SW1(config)#spanning-tree portfast bpduguard default
+```
+
+### Root Guard
+
+If you enable root guard on an interface, even if it receives a superior BPDU (lower bridge ID)
+on that interface , the switch will not accept the new switch as the root bridge.
+the interface will be disabled.
+
+### Loop Guard
+
+If you enable loop guard on an interface, even if the interface stops receiving BPDUs, it`will not 
+start forwarding. The interface will be disabled.
+
+## Spanning Tree Configuration
+
+
+### Spanning Tree mode
+
+```Cisco
+SW1(config)#spanning-tree mode ?
+  mst   multiple spanning tree mode
+  pvst  Per-Vlan spanning tree mode
+  rapid-pvst Per-Vlan rapid spanning tree mode //default
+
+SW1(config)#spanning-tree mode pvst
+```
+
+### Primary Root Bridge
+
+```Cisco
+SW1(config)#spanning-tree vlan 1 root primary
+
+SW1(config)#do show spanning-tree
+```
+
+The *spanning-tree vlan (vlan-number) root primary* command sets the STP priority to 24576.
+if another switch already has a priority lower than 24576, it sets this switch's priority 
+to 4096 less than the other switch's priority.
+
+### Secondary Root Bridge
+
+```Cisco
+SW1(config)#spanning-tree vlan 1 root secondary
+
+SW1(config)#do show spanning-tree
+```
+
+The *spanning-tree vlan (vlan-number) root secondary* command sets the STP priority to 28672.
+
+### STP Port Setting
+
+```Cisco
+SW1(config)#spanning-tree vlan 1 cost 200
+SW1(config)#spanning-tree vlan 1 port-priority 32
+
+```
+
 ## Review
 
+
 - STP state/timers
 - STP BPDU
 - STP optional features