SIMULATION
Acme is small export company that has an existing enterprise network comprised of 5
switches; CORE,DSW1,
DSW2,ASW1 and ASW2. The topology diagram indicates their desired pre-VLAN spanning
tree mapping.
Previous configuration attempts have resulted in the following issues:
– CORE should be the root bridge for VLAN 20; however, DSW1 is currently the root bridge
for VLAN 20.
– Traffic for VLAN 30 should be forwarding over the gig 1/0/6 trunk port between DSW1 and
DSW2.
However VLAN 30 is currently using gig 1/0/5.
– Traffic for VLAN 40 should be forwarding over the gig 1/0/5 trunk port between DSW1 and
DSW2.
However VLAN 40 is currently using gig 1/0/6.
You have been tasked with isolating the cause the these issuer and implementing the
appropriate solutions. You task is complicated by the fact that you only have full access to
DSW1, with isolating the cause of these issues and implementing the appropriate solutions,
Your task is complicated by the fact that you only have full access to DSW1, with the enable
secret password cisco. Only limited show command access is provided on CORE, and
DSW2 using the enable 2 level with a password of acme. No configuration changes will be
possible on these routers. No access is provided to ASW1 or ASW2.
hostname DSW1
!
enable secret 5 $1$wN16$j5RnayatKfxaKxhX30TVo0
!
no aaa new-model
switch 1 provision ws-c3750g-24t
ip subnet-zero
!
no file verify auto
!
spanning-tree mode pvst
spanning-tree extend systen-id
spanning-tree “vlan 20 priority 28672
spanning-tree vlan 30 priority 24576
!
vlan internal allocation policy ascending
!
interface GigabitEthernet1/0/1
description trunk line to ASW1
switchport trunk encapsulation dotlq
switchport mode trunk
switchport nonegotiate
speed 100
duplex full
!
interface GigabitEthernet1/0/2
shutdown
!
interface GigabitEthernet1/0/3
shutdown
!
interface GigabitEthernet1/0/4
shutdown
!
interface GigabitEthernet1/0/5
description trunk line to DSW 2
switchport trunk encapsulation dotlq
switcbport mode trunk
switchport nonegotiate
speed 100
duplex full
!
interface GigabitEthernet1/0/6
description trunk line to DSW 2
switchport trunk encapsulation dotlq
switchport mode trunk
switchport nonegotiate
speed 100
duplex full
!
interface GigabitEthemet1/0/7
shutdown
!
interface GigabitEthemet1/0/8
shutdown
!
Interface GigabitEthernetl/0/9
description trunk line to CORE
switchport trunk encapsulation dotlq
switchport mode trunk
!
end
DSW1# Show sp
DSW1# Show spanning-tree
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 0016. 4658. f300
Cost 19
Port 9 (GigabitEthernet/0/9)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 0016. 46fa. 9b00
Hello Time 2 sec Max Age 20 sec Forward Delay I5 sec
Aging Time 300
VLAN0020
Spanning three enabled protocol ieee
Root ID Priority 28692
Address 0016. 46fa. 9b00
This bridge is the root
Bridge ID Priority 28692 (priority 28672 sys-id-ext 20)
Address 0016. 46fa. 9b00
Hello Time 2 sec Max Age 20 sec Forward Delay I5 sec
Aging Time 300
VLAN0020
Spanning three enabled protocol ieee
Root ID Priority 28692
Address 0016. 46fa. 9b00
This bridge is the root
Bridge ID Priority 28692 (priority 28672 sys-id-ext 20)
Address 0016. 46fa. 9b00
Hello Time 2 sec Max Age 20 sec Forward Delay I5 sec
Aging Time 300
VLAN0030
Spanning three enabled protocol ieee
Root ID Priority 24606
This bridge is the root
Bridge ID Priority 28692 (priority 28672 sys-id-ext 20)
Address 0016. 46fa. 9b00
Hello Time 2 sec Max Age 20 sec Forward Delay I5 sec
Aging Time 300
VLAN0040
Spanning three enabled protocol ieee
Root ID Priority 24616
Address 0016. 46fa. 6a00
Cost 19
Port 9 (GigabitEthernet/0/9)
Hello Time 2 sec Max Age 20 sec Forward Delay I5 sec
Bridge ID Priority 32808 (priority 32768 sys-id-ext 40)
Address 0016. 46fa. 9b00
Hello Time 2 sec Max Age 20 sec Forward Delay I5 sec
Aging Time 300
DSW1#
Answer: See the explanation.
Explanation:
DSW1#conf t
DSW1(config)#spanning-tree vlan 20 priority 61440
DSW1(config)#int g1/0/5
DSW1(config-if)#spanning-tree vlan 40 cost 1
DSW1(config-if)#no shut
DSW1(config-if)#exit
DSW1(config)#int g1/0/6
DSW1(config-if)#spanning-tree vlan 30 port-priority 64
DSW1(config-if)#no shut
DSW1(config-if)#end
DSW1#copy run start
Verification:
DSW1# show spanning-tree vlan 20
DSW1# show spanning-tree vlan 40
DSW2# show spanning-tree vlan 30