Spanning Tree Protocol (STP) en GNS3
Spanning Tree Protocol es un protocolo de capa 2 (enlace de datos) del modelo OSI. Este protocolo esta basado en un algoritmo diseñado por Radia Perlman. La función principal de STP es gestionar la presencia de loops en las topologias de red debido a la existencia de enlaces redundantes, estos enlaces redundantes son necesarios en varios casos para garantizar la disponibilidad de las conexiones. STP permite activar o desactivar automáticamente los enlaces de conexión de forma que se garantice que la topologia este libre de loops. Si existen varios enlaces y en el caso de que un enlace falle, otro enlaces puede seguir soportando el trafico de la red.
Tologia Spanning Tree Protocol |
El objetivo de esta practica es analizar la configuración y el funcionamiento básico del Spanning Tree Protocol (STP). En GNS3 vamos utilizar el modulo NM-16ESW, asi que lo primero que haremos es agregar el modulo NM-16ESW al router. Si necesitas ayudar del como agregar el modulo revisa este enlace.
Una vez configurado los cuatro Switches con el modulo NM-16ESW, iniciamos los routers y realizamos las configuraciones básicas.Spanning Tree Protocol en GNS3 |
Configuración básica del Switch1
SW1>enable
SW1#configure terminal
SW1(config)#hostname Switch1
Switch1(config)#enable secret cisco
Switch1(config)#no ip domain lookup
Switch1(config)#interface Vlan1
Switch1(config-if)#ip address 192.168.1.1 255.255.255.0
Switch1(config-if)#no shut
Switch1(config-if)#line con 0
Switch1(config-line)#exec-timeout 0 0
Switch1(config-line)#logging synchronous
Switch1(config-line)#password cisco2
Switch1(config-line)#login
Switch1(config-line)#exit
Switch1(config)#line vty 0 15
Switch1(config-line)#logging synchronous
Switch1(config-line)#password cisco3
Switch1(config-line)#login
Switch1(config-line)#end
Switch1#copy running-config startup-config
Destination filename [startup-config]?
Building configuration...
[OK]
Switch1#
Configuracion Switch2
SW2>enable
SW2#configure terminal
SW2(config)#hostname Switch2
Switch2(config)#enable secret cisco
Switch2(config)#no ip domain lookup
Switch2(config)#interface Vlan1
Switch2(config-if)#ip address 192.168.1.2 255.255.255.0
Switch2(config-if)#no shut
Switch2(config-if)#line con 0
Switch2(config-line)#exec-timeout 0 0
Switch2(config-line)#logging synchronous
Switch2(config-line)#password cisco2
Switch2(config-line)#login
Switch2(config-line)#exit
Switch2(config)#line vty 0 15
Switch2(config-line)#logging synchronous
Switch2(config-line)#password cisco3
Switch2(config-line)#login
Switch2(config-line)#end
Switch2#copy running-config startup-config
Destination filename [startup-config]?
Building configuration...
[OK]
Switch2#
Configuración Switch3
SW3>enable
SW3#configure terminal
SW3(config)#hostname Switch3
Switch3(config)#enable secret cisco
Switch3(config)#no ip domain lookup
Switch3(config)#interface Vlan1
Switch3(config-if)#ip address 192.168.1.3 255.255.255.0
Switch3(config-if)#no shut
Switch3(config-if)#line con 0
Switch3(config-line)#exec-timeout 0 0
Switch3(config-line)#logging synchronous
Switch3(config-line)#password cisco2
Switch3(config-line)#login
Switch3(config-line)#exit
Switch3(config)#line vty 0 15
Switch3(config-line)#logging synchronous
Switch3(config-line)#password cisco3
Switch3(config-line)#login
Switch3(config-line)#end
Switch3#copy running-config startup-config
Destination filename [startup-config]?
Building configuration...
[OK]
Switch3#
Configuración Switch4
SW4>enable
SW4#configure terminal
SW4(config)#hostname Switch4
Switch4(config)#enable secret cisco
Switch4(config)#no ip domain lookup
Switch4(config)#interface Vlan1
Switch4(config-if)#ip address 192.168.1.4 255.255.255.0
Switch4(config-if)#no shut
Switch4(config-if)#line con 0
Switch4(config-line)#exec-timeout 0 0
Switch4(config-line)#logging synchronous
Switch4(config-line)#password cisco2
Switch4(config-line)#login
Switch4(config-line)#exit
Switch4(config)#line vty 0 15
Switch4(config-line)#logging synchronous
Switch4(config-line)#password cisco3
Switch4(config-line)#login
Switch4(config-line)#end
Switch4#copy running-config startup-config
Destination filename [startup-config]?
Building configuration...
[OK]
Switch4#
Configuramos las interfaces en modo trunk
Switch1(config)#interface range fastEthernet 1/1 - 3
Switch1(config-if-range)#switchport mode trunk
Switch1(config-if-range)#no shutdown
Switch1(config-if-range)#end
Switch1#
Switch2(config)#interface range fastEthernet 1/1 - 3
Switch2(config-if-range)#switchport mode trunk
Switch2(config-if-range)#no shutdown
Switch2(config-if-range)#end
Switch2#
Switch3(config)#interface range fastEthernet 1/1 - 3
Switch3(config-if-range)#switchport mode trunk
Switch3(config-if-range)#no shutdown
Switch3(config-if-range)#end
Switch3#
Switch4(config)#interface range fastEthernet 1/1 - 3
Switch4(config-if-range)#switchport mode trunk
Switch4(config-if-range)#no shutdown
Switch4(config-if-range)#end
Switch4#
Verficamos STP
Switch1#show spanning-tree brief
VLAN1
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address c204.1490.0000
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768
Address c204.1490.0000
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
-------------------- ------- ---- ----- --- ----- -------------------- -------
FastEthernet1/1 128.42 128 19 FWD 0 32768 c204.1490.0000 128.42
FastEthernet1/2 128.43 128 19 FWD 0 32768 c204.1490.0000 128.43
FastEthernet1/3 128.44 128 19 FWD 0 32768 c204.1490.0000 128.44
Switch2#show spanning-tree brief
VLAN1
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address c204.1490.0000
Cost 19
Port 43 (FastEthernet1/2)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768
Address c205.1490.0000
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
-------------------- ------- ---- ----- --- ----- -------------------- -------
FastEthernet1/1 128.42 128 19 FWD 19 32768 c205.1490.0000 128.42
FastEthernet1/2 128.43 128 19 FWD 0 32768 c204.1490.0000 128.42
FastEthernet1/3 128.44 128 19 FWD 19 32768 c205.1490.0000 128.44
Switch3#show spanning-tree brief
VLAN1
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address c204.1490.0000
Cost 19
Port 42 (FastEthernet1/1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768
Address c206.1490.0000
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
-------------------- ------- ---- ----- --- ----- -------------------- -------
FastEthernet1/1 128.42 128 19 FWD 0 32768 c204.1490.0000 128.44
FastEthernet1/2 128.43 128 19 BLK 19 32768 c205.1490.0000 128.44
FastEthernet1/3 128.44 128 19 FWD 19 32768 c206.1490.0000 128.44
Switch4#show spanning-tree brief
VLAN1
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address c204.1490.0000
Cost 19
Port 44 (FastEthernet1/3)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768
Address c207.1490.0000
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
-------------------- ------- ---- ----- --- ----- -------------------- -------
FastEthernet1/1 128.42 128 19 BLK 19 32768 c206.1490.0000 128.44
FastEthernet1/2 128.43 128 19 BLK 19 32768 c205.1490.0000 128.42
FastEthernet1/3 128.44 128 19 FWD 0 32768 c204.1490.0000 128.43
Otro comando para verificar el Switch Root.
Switch1#show spanning-tree root
VLAN1
Root ID Priority 32768
Address c204.1490.0000
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Para mostrar los puertos bloqueados
Switch4#show spanning-tree blockedports
Name Blocked Interfaces List
-------------------- ------------------------------------
VLAN1 Fa1/1, Fa1/2
Number of blocked ports (segments) in the system : 2
Debuggin de STP en GNS3
Switch1#debug spanning-tree ?
all All Spanning Tree debugging messages
backbonefast BackboneFast events
bpdu Spanning tree bridge protocol data units
bpdu-opt Optimized BPDU handling
config Spanning tree config changes
etherchannel EtherChannel support
events Spanning tree topology events
exceptions Spanning tree exceptions
general Spanning tree general
pvst+ PVST+ events
root Spanning tree root events
snmp Spanning Tree SNMP handling
uplinkfast UplinkFast events
Como se muestra en la salida anterior, hay varias opciones disponibles en GNS3. Nosotros activaremos uno en especifico, el debug de los eventos de la topologia de Spanning Tree.
Switch1#debug spanning-tree events
Spanning Tree event debugging is on
Eleccion de Root Bridge
Un Root Switch es el Switch que tenga el Bridge ID (BID) mas pequeña. El bridge ID esta compuesto por:
La prioridad.
La mac address.
Si en todos los Switches son iguales en la prioridad, entonces busca la dirección MAC mas pequeña. En este ejemplo como en todos los switches la prioridad es la misma entonces lo que tomara para elegir el root bridge sera el switch que tenga la mac address mas pequeña. En nuestro caso el Root Brigde con la Mac Address mas pequeña es el Switch1. Ahora veamos un ejemplo de como cambiar la prioridad para que el Switch2 sea el Root.
Cambiar a que Switch2 sea el Root.
Para que el Switch2 sea elegido como Root lo que haremos es cambiar la prioridad y para esto se hace de la siguiente manera.
Switch2(config)#spanning-tree vlan 1 priority 4096
Al hacer esto, las notificaciones en consola del STP se han generado en cada Switch.
Switch1#
*Mar 1 00:53:30.151: STP: VLAN1 heard root 4096-c205.1490.0000 on Fa1/1
*Mar 1 00:53:30.151: current Root has 32768-c204.1490.0000
*Mar 1 00:53:30.151: supersedes 32768-c204.1490.0000
*Mar 1 00:53:30.151: STP: VLAN1 new root is 4096, c205.1490.0000 on port Fa1/1, cost 19
Switch2#
*Mar 1 00:52:51.147: STP: VLAN1 we are the spanning tree root
*Mar 1 00:52:51.323: STP: VLAN1 Topology Change rcvd on Fa1/1
*Mar 1 00:52:51.331: STP: VLAN1 Topology Change rcvd on Fa1/3
*Mar 1 00:53:21.331: STP: VLAN1 Topology Change rcvd on Fa1/3
Switch3#
*Mar 1 00:52:19.175: STP: VLAN1 heard root 4096-c205.1490.0000 on Fa1/2
*Mar 1 00:52:19.175: current Root has 32768-c204.1490.0000
*Mar 1 00:52:19.175: supersedes 32768-c204.1490.0000
*Mar 1 00:52:19.179: STP: VLAN1 new root is 4096, c205.1490.0000 on port Fa1/2, cost 19
*Mar 1 00:52:19.251: STP: VLAN1 Fa1/2 -> listening
*Mar 1 00:52:19.259: STP: VLAN1 sent Topology Change Notice on Fa1/2
*Mar 1 00:52:19.331: STP: VLAN1 Fa1/1 -> blocking
*Mar 1 00:52:34.271: STP: VLAN1 Fa1/2 -> learning
*Mar 1 00:52:49.295: STP: VLAN1 sent Topology Change Notice on Fa1/2
*Mar 1 00:52:49.295: STP: VLAN1 Fa1/2 -> forwarding
Switch4#
*Mar 1 00:51:57.111: STP: VLAN1 heard root 4096-c205.1490.0000 on Fa1/2
*Mar 1 00:51:57.111: current Root has 32768-c204.1490.0000
*Mar 1 00:51:57.111: supersedes 32768-c204.1490.0000
*Mar 1 00:51:57.111: STP: VLAN1 new root is 4096, c205.1490.0000 on port Fa1/2, cost 19
*Mar 1 00:51:57.143: STP: VLAN1 Fa1/1 -> listening
*Mar 1 00:51:57.207: STP: VLAN1 Fa1/2 -> listening
*Mar 1 00:51:57.211: STP: VLAN1 sent Topology Change Notice on Fa1/2
*Mar 1 00:51:57.259: STP: VLAN1 Fa1/3 -> blocking
*Mar 1 00:51:57.327: STP: VLAN1 Fa1/1 -> blocking
*Mar 1 00:52:12.227: STP: VLAN1 Fa1/2 -> learning
*Mar 1 00:52:27.247: STP: VLAN1 Fa1/2 -> forwarding
Como hemos cambiado la prioridad al Switch2 ahora es el Root.
Switch2#show spanning-tree brief
VLAN1
Spanning tree enabled protocol ieee
Root ID Priority 4096
Address c205.1490.0000
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 4096
Address c205.1490.0000
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
-------------------- ------- ---- ----- --- ----- -------------------- -------
FastEthernet1/1 128.42 128 19 FWD 0 4096 c205.1490.0000 128.42
FastEthernet1/2 128.43 128 19 FWD 0 4096 c205.1490.0000 128.43
FastEthernet1/3 128.44 128 19 FWD 0 4096 c205.1490.0000 128.44
Otros modos de la eleccion de Root Switch es cambiando la prioridad mas baja. Por ejemplo, ahora queremos que el Switch3 sea el Root.Switch3(config)#spanning-tree vlan 1 priority 0
Switch3(config)#spanning-tree vlan 1 priority 0
Switch3(config)#
*Mar 1 01:01:16.907: STP: VLAN1 we are the spanning tree root
*Mar 1 01:01:16.931: STP: VLAN1 Fa1/1 -> listening
*Mar 1 01:01:17.091: STP: VLAN1 Topology Change rcvd on Fa1/1
*Mar 1 01:01:18.039: STP: VLAN1 Topology Change rcvd on Fa1/3
Switch3(config)#end
Switch3#show spanning-tree brief
VLAN1
Spanning tree enabled protocol ieee
Root ID Priority 0
Address c206.1490.0000
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 0
Address c206.1490.0000
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
-------------------- ------- ---- ----- --- ----- -------------------- -------
FastEthernet1/1 128.42 128 19 LIS 0 0 c206.1490.0000 128.42
FastEthernet1/2 128.43 128 19 FWD 0 0 c206.1490.0000 128.43
FastEthernet1/3 128.44 128 19 FWD 0 0 c206.1490.0000 128.44
Otra manera es indicandole que por ejemplo el Switch4 sea el Root.Switch4(config)# spanning-tree vlan 1 root primary
Switch4(config)#spanning-tree vlan 1 root primary
VLAN 1 bridge priority set to 8192
VLAN 1 bridge max aging time unchanged at 20
VLAN 1 bridge hello time unchanged at 2
VLAN 1 bridge forward delay unchanged at 15
Switch4#show spanning-tree brief
VLAN1
Spanning tree enabled protocol ieee
Root ID Priority 8192
Address c207.1490.0000
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 8192
Address c207.1490.0000
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
-------------------- ------- ---- ----- --- ----- -------------------- -------
FastEthernet1/1 128.42 128 19 FWD 0 8192 c207.1490.0000 128.42
FastEthernet1/2 128.43 128 19 FWD 0 8192 c207.1490.0000 128.43
FastEthernet1/3 128.44 128 19 FWD 0 8192 c207.1490.0000 128.44
6 comentarios
quisiera cambiar los modos de spanning tree en GNS3 ..... los comandos no me aparecen
ResponderEliminarusa oui gns3 , no uses el nm-16esw
Eliminarquisiera cambiar los modos de spanning tree en GNS3 ..... los comandos no me aparecen
ResponderEliminargracias
ResponderEliminarGracias me sirvió de mucho para aprender y comprender mejor.
ResponderEliminarGracias me ayudo mucho
ResponderEliminar