CCNP3 Lab 3 4 en Multiple Spanning Tree

8/11/2019 CCNP3 Lab 3 4 en Multiple Spanning Tree

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1 - 12 CCNP: Building Multilayer Switched Networks v5.0 - Lab 3-4 Copyright2006, Cisco Systems, Inc

Lab 3-4 Multiple Spanning Tree

Objective

The purpose of this lab is to observe the behavior of MST (multiplespanning tree).

Scenario

Four switches have just been installed. The distribution layer switches areCatalyst 3560s, and the access layer switches are Catalyst 2960s. Thereare redundant uplinks between the access layer and distribution layer.Because of the possibility of bridging loops, spanning tree logicallyremoves any redundant links. In this lab, we will group VLANs using MSTso that we can have less spanning tree instances running at once to saveswitch CPU load.

Step 1

Start by deleting vlan.dat, erasing the startup configuration, and reloadingyour switches. After reloading the switches, give them hostnames.Configure ports f0/7 through f0/12 to be trunks. On the 3560s, you firstneed to set the trunk encapsulation to dot1q. On the 2960s, only dot1q issupported, so it does not need to be set, but the mode still needs to bechanged to trunk. If you do not set the mode of the ports to be trunk, the


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links do not form trunks and remain access ports (default mode on a 3560or 2960 is dynamic auto; default mode on a 3550 or 2950 is dynamicdesirable).

DLS1#conf i gur e t ermi nalEnt er conf i gur at i on commands, one per l i ne. End wi t h CNTL/ Z.DLS1( conf i g) #i nt er f ace range f 0/ 7 - 12

DLS1( conf i g- i f - r ange)#swi t chport t r unk encapsul ati on dot 1qDLS1( conf i g- i f - r ange)#swi t chport mode t r unk

Step 2

Configure all switches with VTP mode transparent and VTP domainCISCO. Add VLANs 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 to all ofthem. Use the show vlan briefcommand to view the VLANconfigurations.

DLS1#conf i gur e termi nalEnt er conf i gurat i on commands, one per l i ne. End wi t h CNTL/ Z.DLS1( conf i g) #vtp mode transparentSet t i ng devi ce t o VTP TRANSPARENT mode.

DLS1( conf i g) #vtp domain CISCOChangi ng VTP domai n name f r om NULL t o CI SCODLS1( conf i g) #vl an 10, 20, 30, 40, 50, 60, 70, 80, 90, 100DLS1( conf i g-vl an) #endDLS1#show vl an br i ef00: 11: 56: %SYS- 5- CONFI G_I : Conf i gur ed f r omconsol e by consol e

VLAN Name St at us Por t s- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -1 def aul t act i ve Fa0/ 1, Fa0/ 2, Fa0/ 3, Fa0/ 4

Fa0/ 5, Fa0/ 6, Fa0/ 7, Fa0/ 8Fa0/ 9, Fa0/ 10, Fa0/ 11, Fa0/ 12Fa0/ 13, Fa0/ 14, Fa0/ 15, Fa0/ 16Fa0/ 17, Fa0/ 18, Fa0/ 19, Fa0/ 20Fa0/ 21, Fa0/ 22, Fa0/ 23, Fa0/ 24Gi 0/ 1, Gi 0/ 2

10 VLAN0010 act i ve

20 VLAN0020 act i ve30 VLAN0030 act i ve40 VLAN0040 act i ve50 VLAN0050 act i ve60 VLAN0060 act i ve70 VLAN0070 act i ve80 VLAN0080 act i ve90 VLAN0090 act i ve100 VLAN0100 act i ve1002 f ddi - def aul t act / unsup1003 t oken- r i ng- def aul t act / unsup1004 f ddi net- def aul t act / unsup1005 t r net- def aul t act / unsup

Step 3

If you issue the show spanning-treecommand on one of the switches,you see 11 spanning tree instances running.

DLS1#show spanni ng- t r ee

VLAN0001Spanni ng tr ee enabl ed pr otocol i eeeRoot I D Pri or i t y 32769

Addr ess 000a. b8a9. d680Cost 19


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Por t 13 ( Fast Et hernet 0/ 11)Hel l o Ti me 2 sec Max Age 20 sec For ward Del ay 15 sec

Br i dge I D Pr i or i t y 32769 ( pr i or i t y 32768 sys- i d- ext 1)Addr ess 000a. b8a9. d780Hel l o Ti me 2 sec Max Age 20 sec For ward Del ay 15 secAgi ng Ti me 300

I nt erf ace Rol e St s Cost Pri o. Nbr Type- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Fa0/ 7 Desg FWD 19 128. 9 P2pFa0/ 8 Desg FWD 19 128. 10 P2pFa0/ 9 Desg FWD 19 128. 11 P2pFa0/ 10 Desg FWD 19 128. 12 P2pFa0/ 11 Root FWD 19 128. 13 P2pFa0/ 12 Al t n BLK 19 128. 14 P2p


Addr ess 000a. b8a9. d680

Cost 19Por t 13 ( Fast Et hernet 0/ 11)Hel l o Ti me 2 sec Max Age 20 sec For ward Del ay 15 sec


I nt erf ace Rol e St s Cost Pri o. Nbr Type- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Fa0/ 7 Desg FWD 19 128. 9 P2pFa0/ 8 Desg FWD 19 128. 10 P2pFa0/ 9 Desg FWD 19 128. 11 P2pFa0/ 10 Desg FWD 19 128. 12 P2p

Fa0/ 11 Root FWD 19 128. 13 P2pFa0/ 12 Al t n BLK 19 128. 14 P2p


Addr ess 000a. b8a9. d680Cost 19Por t 13 ( Fast Et hernet 0/ 11)Hel l o Ti me 2 sec Max Age 20 sec For ward Del ay 15 sec

Br i dge I D Pr i or i t y 32788 ( pr i or i t y 32768 sys- i d- ext 20)Addr ess 000a. b8a9. d780Hel l o Ti me 2 sec Max Age 20 sec For ward Del ay 15 sec

Agi ng Ti me 300



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Addr ess 000a. b8a9. d680Cost 19

Por t 13 ( Fast Et hernet 0/ 11)Hel l o Ti me 2 sec Max Age 20 sec For ward Del ay 15 sec


I nt erf ace Rol e St s Cost Pri o. Nbr Type- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Fa0/ 7 Desg FWD 19 128. 9 P2pFa0/ 8 Desg FWD 19 128. 10 P2pFa0/ 9 Desg FWD 19 128. 11 P2pFa0/ 10 Desg FWD 19 128. 12 P2pFa0/ 11 Root FWD 19 128. 13 P2p

Fa0/ 12 Al t n BLK 19 128. 14 P2p





Spanning tree is running a separate spanning tree instance for each VLANwe created, plus VLAN 1. This method assumes that each VLAN could berunning on a differently shaped topology. However, in many networks,multiple VLANs follow the same physical topology, so multiple spanning-tree calculations for the same topologies can get redundant. MST (multiplespanning tree) lets you configure different spanning tree instances. Eachinstance can hold a group of VLANs and gets its own spanning treecalculation.

MST is convenient in that it is backward compatible with PVST. Twoswitches only run MST with each other if they are in the same MST region.

An MST region is defined by switches having identical region names,


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revision numbers, and VLAN-to-instance assignments. If they differ by anysingle attribute, they are considered different MST regions and fall back toPVST.

Step 4

To configure MST, first use the global configuration command spanning-tree mode mston all four switches.

DLS1( conf i g) #spanning-tree mode mst

By default, all VLANs are assigned to instance 0, but can be movedaround to different instances when MST is configured. Issue the showspanning-treecommand and observe that there is only one spanning tree(instance 0) coming up. Also notice that the mode is listed as MSTP.

DLS1#show spanning-tree

MST00

Spanni ng t r ee enabl ed prot ocol mst pRoot I D Pri or i t y 32768Addr ess 000a. b8a9. d680Cost 0Por t 13 ( Fast Et hernet 0/ 11)Hel l o Ti me 2 sec Max Age 20 sec For ward Del ay 15 sec


I nt erf ace Rol e St s Cost Pri o. Nbr Type- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Fa0/ 7 Desg FWD 200000 128. 9 P2pFa0/ 8 Desg BLK 200000 128. 10 P2p

Fa0/ 9 Desg FWD 200000 128. 11 P2pFa0/ 10 Desg FWD 200000 128. 12 P2pFa0/ 11 Root FWD 200000 128. 13 P2pFa0/ 12 Al t n BLK 200000 128. 14 P2p

If you use the show spanning-tree mst configurationcommand, youcan see a switchs current MST configuration. Because you have notconfigured any MST region settings, the switch shows the default settings.

DLS1#show spanning-tree mst configurationName [ ]Revi si on 0I nst ance Vl ans mapped- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

0 1- 4094- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Step 5

Now that MST has been enabled, we can configure the MST regionsettings to group VLANs. We use the region name CISCO and a revisionnumber of 1. We put VLANs 20 through 50 into instance 1, and 80 and100 into instance 2. The rest of the VLANs remain in instance 0, the


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default. To begin modifying the MST configuration, type the globalconfiguration command spanning-tree mst configuration. ConfiguringMST is different from other switch configurations, because changes arenot applied until you are done, and you can abort changes if you want to.

Note:You must apply identical configurations on each switch for MST to

work properly.DLS1#conf i gur e t ermi nalEnt er conf i gur at i on commands, one per l i ne. End wi t h CNTL/ Z.DLS1( conf i g) #spanning-tree mst configurationDLS1( conf i g-mst ) #

When you are in MST configuration mode, you can view the currentconfiguration using the show currentcommand. You do not need to leaveconfiguration mode to execute this command. Notice that the output isidentical to show spanning-tree mst configuration.

DLS1( conf i g- mst ) #show currentCur r ent MST conf i gur at i onName [ ]Revi si on 0I nst ance Vl ans mapped- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -0 1- 4094- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Change the region name by typing name name. Change the revisionnumber by typing revision number.

DLS1(conf i g- mst ) #name CI SCODLS1( conf i g- mst ) #r evi si on 1

The last configuration change you have to make is putting VLANs intoinstances. Use the command instance numbervlan vlan_range. Theinstance number can be between 0 and 15. Remember that 0 is thedefault instance number.

DLS1( conf i g-mst ) # i nstance 1 vl an 20- 50DLS1( conf i g-mst ) # i nstance 2 vl an 80, 100

You can verify the changes you are about to make with the showpendingcommand. Remember that the changes that you just entered arenot committed until you type exit. If you do not like the changes you made,you can leave the prompt without committing them by typing abort. In theoutput below, notice the difference between show currentand showpending.

DLS1( conf i g- mst ) #show currentCur r ent MST conf i gur at i onName [ ]Revi si on 0I nst ance Vl ans mapped- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -0 1- 4094


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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

DLS1( conf i g- mst ) #show pendingPendi ng MST conf i gur at i onName [ CI SCO]Revi si on 1I nst ance Vl ans mapped

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -0 1-19, 51- 79, 81- 99, 101-40941 20- 502 80, 100- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

DLS1( conf i g- mst ) #exi t

If you enter the show spanning-tree mst configuration command, youcan see that the current configuration reflects the changes you justcommitted. Remember to perform the same configuration on all fourswitches.

DLS1#show span mst configuration

Name [ CI SCO]Revi si on 1I nst ance Vl ans mapped- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -0 1-19, 51- 79, 81- 99, 101-40941 20- 502 80, 100- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Why do the switches wait until you are finished making changes to MST tocommit them, rather that changing MST as you enter commands (likemost switch commands)?

Verify that you have separate instances of spanning tree running for eachMST instance:

DLS1#show spanning-tree

MST00Spanni ng t r ee enabl ed prot ocol mst pRoot I D Pri or i t y 32768





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Challenge

You can modify per-instance MST spanning tree attributes the same way

you can modify per-VLAN attributes. Make DLS1 the root of instance 1and DLS2 the root of instance 2.

HINT: Use a question mark on the global configuration commandspanning-tree mst ?.


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END OF LAB FINAL CONFIGS:

DLS1#show r unni ng- conf i g!host name DLS1!!vt p domai n CI SCOvt p mode t r ansparent!!!!!spanni ng- t r ee mst conf i gur at i on

name CI SCOr evi si on 1i nst ance 1 vl an 20- 50i nst ance 2 vl an 80, 100

!spanni ng- t r ee mst 1 pr i ori t y 24576!!vl an 10, 20, 30, 40, 50, 60, 70, 80, 90, 100!!i nt er f ace Fast Et her net 0/ 7swi t chport t r unk encapsul at i on dot1qswi t chpor t mode t r unk

!

i nt er f ace Fast Et her net 0/ 8swi t chport t r unk encapsul at i on dot1qswi t chpor t mode t r unk

!i nt er f ace Fast Et her net 0/ 9swi t chport t r unk encapsul at i on dot1qswi t chpor t mode t r unk

!i nt erf ace Fast Et hernet 0/ 10swi t chport t r unk encapsul at i on dot1qswi t chpor t mode t r unk



!!end

DLS2#show r unni ng- conf i g!host name DLS2


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!!vt p domai n CI SCOvt p mode t r ansparent!!spanni ng- t r ee mode mst

!spanni ng- t r ee mst conf i gur at i onname CI SCOr evi si on 1i nst ance 1 vl an 20- 50i nst ance 2 vl an 80, 100

!spanni ng- t r ee mst 2 pr i ori t y 24576!!vl an 10, 20, 30, 40, 50, 60, 70, 80, 90, 100!!!i nt er f ace Fast Et her net 0/ 7

swi t chport t r unk encapsul at i on dot1qswi t chpor t mode t r unk!i nt er f ace Fast Et her net 0/ 8swi t chport t r unk encapsul at i on dot1qswi t chpor t mode t r unk

!i nt er f ace Fast Et her net 0/ 9swi t chport t r unk encapsul at i on dot1qswi t chpor t mode t r unk


!

i nt erf ace Fast Et hernet 0/ 11swi t chport t r unk encapsul at i on dot1qswi t chpor t mode t r unk


!!end

ALS1#show r unni ng- conf i g!host name ALS1!

!vt p domai n CI SCOvt p mode t r ansparent!!spanni ng- t r ee mode mst!spanni ng- t r ee mst conf i gur at i onname CI SCOr evi si on 1i nst ance 1 vl an 20- 50


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i nst ance 2 vl an 80, 100!!vl an 10, 20, 30, 40, 50, 60, 70, 80, 90, 100!!i nt er f ace Fast Et her net 0/ 7

swi t chpor t mode t r unk!i nt er f ace Fast Et her net 0/ 8swi t chpor t mode t r unk

!i nt er f ace Fast Et her net 0/ 9swi t chpor t mode t r unk

!i nt erf ace Fast Et hernet 0/ 10swi t chpor t mode t r unk


!i nt erf ace Fast Et hernet 0/ 12

swi t chpor t mode t r unk!!end

ALS2#show r unni ng- conf i g!host name ALS2!!vt p domai n CI SCOvt p mode t r ansparent!!spanni ng- t r ee mode mst

!spanni ng- t r ee mst conf i gur at i onname CI SCOr evi si on 1i nst ance 1 vl an 20- 50i nst ance 2 vl an 80, 100

!!vl an 10, 20, 30, 40, 50, 60, 70, 80, 90, 100!!i nt er f ace Fast Et her net 0/ 7swi t chpor t mode t r unk

!i nt er f ace Fast Et her net 0/ 8

swi t chpor t mode t r unk!i nt er f ace Fast Et her net 0/ 9swi t chpor t mode t r unk



!


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i nt erf ace Fast Et hernet 0/ 12swi t chpor t mode t r unk

!!end

CCNP3 Lab 3 4 en Multiple Spanning Tree

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