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CCNP BCMSN(642-812) Lab – Spanning-Tree(STP)
By admin | May 19, 2009
Spanning-Tree Protocol is a link management protocol that provides path redundancy while preventing undesirable loops in the network. For an Ethernet network to function properly, only one active path can exist between two stations.
Multiple active paths between stations cause loops in the network. If a loop exists in the network topology, the potential exists for duplication of messages. When loops occur, some switches see stations appear on both sides of the switch. This condition confuses the forwarding algorithm and allows duplicate frames to be forwarded.
To provide path redundancy, Spanning-Tree Protocol defines a tree that spans all switches in an extended network. Spanning-Tree Protocol forces certain redundant data paths into a standby (blocked) state. If one network segment in the Spanning-Tree Protocol becomes unreachable, or if Spanning-Tree Protocol costs change, the spanning-tree algorithm reconfigures the spanning-tree topology and reestablishes the link by activating the standby path.
Spanning-Tree Protocol operation is transparent to end stations, which are unaware whether they are connected to a single LAN segment or a switched LAN of multiple segments
There is a lab about STP in Cisco CCNP 642-812 / 642-892 exam.
Requirements:
You will configure FastEthernet ports 0/12 through 0/24 for users who belong to VLAN 20. Also, all VLAN and VTP configurations are to be completed in global configuration mode as VLAN database mode is being deprecated by Cisco. You are required to accomplish the following tasks:
1. Ensure the switch does not participate in VTP but forwards VTP advertisements received on trunk ports.
2. Ensure all non-trunking interfaces (Fa0/1 to Fa0/24) transition immediately to the forwarding state of Spanning-Tree.
3. Ensure all FastEthernet interfaces are in a permanent non-trunking mode.
4. Place FastEthernet interfaces 0/12 through 0/24 in VLAN 20
Solutions:
*But dont enter ‘vtp mode transparent’ command at begining of configuration. if you do that you will not be able to add vlan 10 to the switch. vlan 10 is not existing in the switch and it needs to be created, it will create automatically if you follow the pass4sure answer. In transparent mode vlan creation is not possible. So, do every configuration and the last moment change the vtp mode to transparent.
Switch#conf t
Switch(config)#interface range fa0/1 – 24
Switch(config-if-range)#switchport mode access (Brings the interfaces into access mode)
Switch(config-if-range)#spanning-tree portfast (Enables the PortFast on interface.)
_The fastEthernet interfaces 0/12 through 0/24 should be placed in VLAN 20
Switch(config)#interface range fa0/12 – 24
Switch(config-if-range)#switchport access vlan 20 (Makes the members of vlan 20)
Switch(config-if-range)#exit
Switch(config)#vtp mode transparent
Switch(config)#exit
Switch#copy run start
Spanning tree PortFast is a Catalyst feature that causes a switch or trunk port to enter the spanning tree Forwarding state immediately, bypassing the Listening and Learning states. IOS-based switches only use PortFast on access ports connected to end stations. When a device is connected to a port, the port normally enters the spanning tree Listening state. When the Forward Delay timer expires, the port enters the Learning state. When the Forward Delay timer expires a second time, the port is transitioned to the Forwarding or Blocking state. When PortFast is enabled on a switch or trunk port, the port is immediately transitioned to the Forwarding state. As soon as the switch detects the link, the port is transitioned to the Forwarding state (less than 2 seconds after the cable is plugged in).
That is all, hope to helpful for you. Best Luck for ur BCMSN 642-812 Exam.
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Tags: 642-812, 642-892, Lab, STP, VTPTopics: 642-812 Exam, 642-892 Exam, CCNP | 9 Comments »
9 Responses to “CCNP BCMSN(642-812) Lab – Spanning-Tree(STP)”
Comments
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May 24th, 2009 at 9:19 pm
*But dont enter ‘vtp mode transparent’ command at begining of configuration. if you do that you will not be able to add vlan 10 to the switch. vlan 10 is not existing in the switch and it needs to be created, it will create automatically if you follow the pass4sure answer. In transparent mode vlan creation is not possible. So, do every configuration and the last moment change the vtp mode to transparent.
Why would you not be able to add a VLAN with VTP in Transparent mode? I would agree if you were putting the VTP on Client mode. You should be able to and VLANs in Transparent mode though.
June 4th, 2009 at 8:11 pm
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Kachy Reply:
June 7th, 2009 at 12:21 am
Yeah, you just need add a link to ciscobible.net!!
July 12th, 2009 at 9:01 pm
I just took the 642-812. I failed.
As I remembered, I had two problems.
1) Vlan 1 is shutdown but I could not enter
interface vlan 1 to “no shutdown”
2) when I enter vtp mode transparent.
It says vtp mode is not available in this version something like that.
I am going to take another shot. Can someone help me ?
Thanks
July 16th, 2009 at 2:28 pm
Configure PortFast as a global default,
affecting all switch ports with a single command
Switch(config)# spanning-tree portfast default
All ports that are configured for access mode
nontrunking) will have PortFast automatically enabled
Boy_Racer Reply:
September 20th, 2009 at 9:30 pm
In a real-world scenario it can be done either globally or using the interface range command. Does anyone know if this also applies in the exam simulation environment?
August 28th, 2009 at 12:25 am
I got 100% in the spanning-tree bit, vtp mode transparent works fine.
Don’t know why the above comment says you can not add vlans before you change to vtp mode transparent as the whole idea of this mode is that it is all local to the switch and does not propagate through the network.
Worked just fine for me
September 20th, 2009 at 9:28 pm
Don’t forget the verification commands:
show run
show vlan brief
These will help determine if you have made all the correct configurations before saving your configuration and existing the Simulation.
January 30th, 2010 at 12:07 pm
Hello.
I know I’m late on this, but if memory serves me correct the default vtp version is version 1, and VTP version 1 does not forward VTP advertisements it receives… correct?
If I’m correct, don’t we need to specify version 2 in order for this to work?
From Cisco’s Site:
http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094c52.shtml
Transparent—VTP transparent switches do not participate in VTP. A VTP transparent switch does not advertise its VLAN configuration and does not synchronize its VLAN configuration based on received advertisements, but transparent switches do forward VTP advertisements that they receive out their trunk ports in VTP Version 2.