Configure DTP

 

Device	Interface	IP Address	Subnet Mask
PC1	NIC	192.168.10.1	255.255.255.0
PC2	NIC	192.168.20.1	255.255.255.0
PC3	NIC	192.168.30.1	255.255.255.0
PC4	NIC	192.168.30.2	255.255.255.0
PC5	NIC	192.168.20.2	255.255.255.0
PC6	NIC	192.168.10.2	255.255.255.0
S1	VLAN 99	192.168.99.1	255.255.255.0
S2	VLAN 99	192.168.99.2	255.255.255.0
S3	VLAN 99	192.168.99.3	255.255.255.0

Objectives

=   Configure static trunking

=   Configure and Verify DTP

Background / Scenario

As the number of switches in a network increases, the administration necessary to manage the VLANs and trunks can be challenging. To ease some of the VLAN and trunking configurations, trunk negotiation between network devices is managed by the Dynamic Trunking Protocol (DTP), and is automatically enabled on Catalyst 2960 and Catalyst 3650 switches.

In this activity, you will configure trunk links between the switches. You will assign ports to VLANs and verify end-to-end connectivity between hosts in the same VLAN. You will configure trunk links between the switches, and you will configure VLAN 999 as the native VLAN.

Instructions

Part 1: Verify VLAN configuration.

Verify the configured VLANs on the switches.

a.     On S1, go to privileged EXEC mode and enter the show vlan brief command to verify the VLANs that are present.

Open configuration window

S1# show vlan brief

 

VLAN Name Status Ports

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

1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4

Fa0/5, Fa0/6, Fa0/7, Fa0/8

Fa0/9, Fa0/10, Fa0/11, Fa0/12

Fa0/13, Fa0/14, Fa0/15, Fa0/16

Fa0/17, Fa0/18, Fa0/19, Fa0/20

Fa0/21, Fa0/22, Fa0/23, Fa0/24

Gig0/1, Gig0/2

99 Management active

999 Native active

1002 fddi-default active

1003 token-ring-default active

1004 fddinet-default active

1005 trnet-default active

b.     Repeat Step 1a on S2 and S3.

Question:

What VLANs are configured on the switches?

Part 2: Create additional VLANs on S2 and S3.

a.     On S2, create VLAN 10 and name it Red.

S2(config)# vlan 10

S2(config-vlan)# name Red

b.     Create VLANs 20 and 30 according to the table below.

VLAN Number	VLAN Name
10	Red
20	Blue
30	Yellow

Blank Line - no additional information

c.     Verify the addition of the new VLANs. Enter show vlan brief at the privileged EXEC mode.

Question:

In addition to the default VLANs, which VLANs are configured on S2?

d.     Repeat the previous steps to create the additional VLANs on S3.

Part 3: Assign VLANs to Ports

Use the switchport mode access command to set access mode for the access links. Use the switchport access vlan vlan-id command to assign a VLAN to an access port.

Ports	Assignments	Network
S2 F0/1 – 8 S3 F0/1 – 8	VLAN 10 (Red)	192.168.10.0 /24
S2 F0/9 – 16 S3 F0/9 – 16	VLAN 20 (Blue)	192.168.20.0 /24
S2 F0/17 – 24 S3 F0/17 – 24	VLAN 30 (Yellow)	192.168.30.0 /24

Blank Line - no additional information

a.     Assign VLANs to ports on S2 using assignments from the table above.

S2(config-if)# interface range f0/1 - 8

S2(config-if-range)# switchport mode access

S2(config-if-range)# switchport access vlan 10

S2(config-if-range)# interface range f0/9 -16

S2(config-if-range)# switchport mode access

S2(config-if-range)# switchport access vlan 20

S2(config-if-range)# interface range f0/17 - 24

S2(config-if-range)# switchport mode access

S2(config-if-range)# switchport access vlan 30

b.     Assign VLANs to ports on S3 using the assignments from the table above.

Now that you have the ports assigned to VLANs, try to ping from PC1 to PC6.

Question:

Was the ping successful? Explain.

Part 4: Configure Trunks on S1, S2, and S3.

Dynamic trunking protocol (DTP) manages the trunk links between Cisco switches. Currently, all the switchports are in the default trunking mode, which is dynamic auto. In this step, you will change the trunking mode to dynamic desirable for the link between switches S1 and S2. The link between switches S1 and S3 will be set as a static trunk. Use VLAN 999 as the native VLAN in this topology.

a.     On switch S1, configure the trunk link to dynamic desirable on the GigabitEthernet 0/1 interface. The configuration of S1 is shown below.

S1(config)# interface g0/1

S1(config-if)# switchport mode dynamic desirable

Question:

What will be the result of trunk negotiation between S1 and S2?

b.     On switch S2, verify that the trunk has been negotiated by entering the show interfaces trunk command. Interface GigabitEthernet 0/1 should appear in the output.

Question:

What is the mode and status for this port?

c.     For the trunk link between S1 and S3, configure interface GigabitEthernet 0/2 as a static trunk link on S1. In addition, disable DTP negotiation on interface G0/2 on S1.

S1(config)# interface g0/2

S1(config-if)# switchport mode trunk

S1(config-if)# switchport nonegotiate

d.     Use the show dtp command to verify the status of DTP.

S1# show dtp

Global DTP information

Sending DTP Hello packets every 30 seconds

Dynamic Trunk timeout is 300 seconds

1 interfaces using DTP

e.     Verify trunking is enabled on all the switches using the show interfaces trunk command.

S1# show interfaces trunk

Port Mode Encapsulation Status Native vlan

Gig0/1 desirable n-802.1q trunking 1

Gig0/2 on 802.1q trunking 1

 

Port Vlans allowed on trunk

Gig0/1 1-1005

Gig0/2 1-1005

 

Port Vlans allowed and active in management domain

Gig0/1 1,99,999

Gig0/2 1,99,999

 

Port Vlans in spanning tree forwarding state and not pruned

Gig0/1 1,99,999

Gig0/2 1,99,999

Question:

What is the native VLAN for these trunks currently?

f.      Configure VLAN 999 as the native VLAN for the trunk links on S1.

S1(config)# interface range g0/1 - 2

S1(config-if-range)# switchport trunk native vlan 999

Question:

What messages did you receive on S1? How would you correct it?

g.     On S2 and S3, configure VLAN 999 as the native VLAN.

h.     Verify trunking is successfully configured on all the switches. You should be able ping one switch from another switch in the topology using the IP addresses configured on the SVI.

i.      Attempt to ping from PC1 to PC6.

Question:

Why was the ping unsuccessful? (Hint: Look at the ‘show vlan brief’ output from all three switches. Compare the outputs from the ‘show interface trunk’ on all switches.)

j.      Correct the configuration as necessary.

Part 5: Reconfigure trunk on S3.

a.     Issue the ‘show interface trunk’ command on S3.

Question:

What is the mode and encapsulation on G0/2?

b.     Configure G0/2 to match G0/2 on S1.

Question:

What is the mode and encapsulation on G0/2 after the change?

c.     Issue the command ‘show interface G0/2 switchport’ on switch S3.

Question:

What is the ‘Negotiation of Trunking’ state displayed?

Close configuration window

Part 6: Verify end to end connectivity.

a.     From PC1 ping PC6.

b.     From PC2 ping PC5.

c.     From PC3 ping PC4.

End of document