3.5.5 Packet Tracer - Configure DTP Answers
Topology
Addressing Table
| 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.
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 activeb. Repeat Step 1a on S2 and S3.
S2# 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 activeS3# 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 activeWhat VLANs are configured on the switches?
VLANs 99 and 999 are configured on all 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 |
S2(config-vlan)# vlan 20 S2(config-vlan)# name Blue S2(config-vlan)# vlan 30 S2(config-vlan)# name Yellow
c. Verify the addition of the new VLANs. Enter show vlan brief in privileged EXEC mode.
S2# 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
10 Red active
20 Blue active
30 Yellow active
99 Management active
999 Native active
1002 fddi-default active
1003 token-ring-default active
1004 fddinet-default active
1005 trnet-default activeIn addition to the default VLANs, which VLANs are configured on S2?
VLAN 10 (Red), VLAN 20 (Blue), VLAN 30 (Yellow), VLAN 99 (Management) and VLAN 999 (Native)
d. Repeat the previous steps to create the additional VLANs on S3.
S3(config)# vlan 10 S3(config-vlan)# name Red S3(config-vlan)# vlan 20 S3(config-vlan)# name Blue S3(config-vlan)# vlan 30 S3(config-vlan)# name Yellow
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 |
a. Assign VLANs to ports on S2 using assignments from the table above.
S2(config)# interface range fastethernet 0/1 - 8 S2(config-if-range)# switchport mode access S2(config-if-range)# switchport access vlan 10 S2(config-if-range)# interface range fastethernet 0/9 - 16 S2(config-if-range)# switchport mode access S2(config-if-range)# switchport access vlan 20 S2(config-if-range)# interface range fastethernet 0/17 - 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.
S3(config)# interface range fastethernet 0/1 - 8 S3(config-if-range)# switchport mode access S3(config-if-range)# switchport access vlan 10 S3(config-if-range)# interface range fastethernet 0/9 - 16 S3(config-if-range)# switchport mode access S3(config-if-range)# switchport access vlan 20 S3(config-if-range)# interface range fastethernet 0/17 - 24 S3(config-if-range)# switchport mode access S3(config-if-range)# switchport access vlan 30
Now that you have the ports assigned to VLANs, try to ping from PC1 to PC6.
Was the ping successful? Explain.
No, the pings failed because the ports between the switches are in VLAN 1 and PC1 and PC6 are in VLAN 10.
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 gigabitethernet 0/1 S1(config-if)# switchport mode dynamic desirable
What will be the result of trunk negotiation between S1 and S2?
A trunk link is established between S1 and S2 (desirable on S1 and auto on S2 negotiate a trunk).
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.
S2# show interfaces trunk
Port Mode Encapsulation Status Native vlan
Gig0/1 auto n-802.1q trunking 1
Port Vlans allowed on trunk
Gig0/1 1-1005
Port Vlans allowed and active in management domain
Gig0/1 1,10,20,30,99,999
Port Vlans in spanning tree forwarding state and not pruned
Gig0/1 1,10,20,30,99,999What is the mode and status for this port?
Mode: Auto | Status: trunking
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 gigabitethernet 0/2 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 DTPe. 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
What is the native VLAN for these trunks currently?
VLAN 1
f. Configure VLAN 999 as the native VLAN for the trunk links on S1.
S1(config)# interface range gigabitethernet 0/1 - 2 S1(config-if-range)# switchport trunk native vlan 999
What messages did you receive on S1? How would you correct it?
S1 reports %CDP-4-NATIVE_VLAN_MISMATCH messages on G0/1 and G0/2. To correct the native VLAN mismatch, configure VLAN 999 as the native VLAN on S2 and S3.
g. On S2 and S3, configure VLAN 999 as the native VLAN.
S2(config)# interface gigabitethernet 0/1 S2(config-if)# switchport mode dynamic auto S2(config-if)# switchport trunk native vlan 999
S3(config)# interface gigabitethernet 0/2 S3(config-if)# switchport mode trunk S3(config-if)# switchport trunk native vlan 999
h. Verify trunking is successfully configured on all the switches. You should be able to ping one switch from another switch in the topology using the IP addresses configured on the SVI.
S1# ping 192.168.99.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.99.2, timeout is 2 seconds: ..!!! Success rate is 60 percent (3/5), round-trip min/avg/max = 0/0/0 ms S1# ping 192.168.99.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.99.3, timeout is 2 seconds: ..!!! Success rate is 60 percent (3/5), round-trip min/avg/max = 0/0/0 ms
i. Attempt to ping from PC1 to PC6.
Why was the ping unsuccessful? (Hint: Look at the ‘show vlan brief’ output from all three switches. Compare the outputs from the ‘show interfaces trunk’ on all switches.)
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
99 Management active
999 Native active
1002 fddi-default active
1003 token-ring-default active
1004 fddinet-default active
1005 trnet-default activeS1# show interfaces trunk Port Mode Encapsulation Status Native vlan Gig0/1 desirable n-802.1q trunking 999 Gig0/2 on 802.1q trunking 999 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
The ping was unsuccessful because VLANs 10, 20 and 30 do not exist on S1. The S1 trunks only carry the VLANs that are active on S1 (1, 99 and 999), so VLAN 10 traffic from PC1 is not forwarded to S3.
j. Correct the configuration as necessary.
S1(config)# vlan 10 S1(config-vlan)# name Red S1(config-vlan)# vlan 20 S1(config-vlan)# name Blue S1(config-vlan)# vlan 30 S1(config-vlan)# name Yellow
Try the ping again from PC1 to PC6: successful.
Part 5: Reconfigure trunk on S3.
a. Issue the ‘show interfaces trunk’ command on S3.
S3# show interfaces trunk
Port Mode Encapsulation Status Native vlan
Gig0/2 on 802.1q trunking 999
Port Vlans allowed on trunk
Gig0/2 1-1005
Port Vlans allowed and active in management domain
Gig0/2 1,10,20,30,99,999
Port Vlans in spanning tree forwarding state and not pruned
Gig0/2 1,10,20,30,99,999What is the mode and encapsulation on G0/2?
Mode: on | Encapsulation: 802.1q
b. Configure G0/2 to match G0/2 on S1.
S3(config)# interface gigabitethernet 0/2 S3(config-if)# switchport nonegotiate
What is the mode and encapsulation on G0/2 after the change?
Mode: on | Encapsulation: 802.1q
c. Issue the command ‘show interfaces G0/2 switchport’ on switch S3.
S3# show interfaces gigabitethernet 0/2 switchport
Name: Gig0/2
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: Off
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 999 (Native)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: All
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Appliance trust: noneWhat is the ‘Negotiation of Trunking’ state displayed?
Off
Part 6: Verify end to end connectivity.
a. From PC1 ping PC6.
C:\> ping 192.168.10.2
Successful
b. From PC2 ping PC5.
C:\> ping 192.168.20.2
Successful
c. From PC3 ping PC4.
C:\> ping 192.168.30.2
Successful
Device Configs - Final
SWITCH S1
! ============================================================== !--- 3.5.5 Packet Tracer - Configure DTP !--- ANSWER SCRIPT FOR SWITCH S1 !--- Usage: copy this whole file and paste it into the S1 terminal (start at the S1> prompt). Every line beginning with "!" is a comment; IOS ignores it, so pasting a comment by accident is harmless. !--- VLANs 99 and 999 and the VLAN 99 SVI are preconfigured on all switches. ! ============================================================== enable configure terminal ! -------------------------------------------------------------- !--- Part 4: Configure Trunks on S1, S2, and S3. ! -------------------------------------------------------------- !--- a and f. G0/1 (to S2): DTP dynamic desirable, native VLAN 999. interface gigabitethernet 0/1 switchport mode dynamic desirable switchport trunk native vlan 999 exit !--- c and f. G0/2 (to S3): static trunk, DTP disabled, native VLAN 999. interface gigabitethernet 0/2 switchport mode trunk switchport nonegotiate switchport trunk native vlan 999 exit !--- j. Create VLANs 10, 20 and 30 on S1 so the trunks carry them (the cause of the failed PC1 to PC6 ping in Step i). vlan 10 name Red exit vlan 20 name Blue exit vlan 30 name Yellow exit end ! -------------------------------------------------------------- !--- Save the configuration to NVRAM. (Press Enter when prompted for the destination filename.) ! -------------------------------------------------------------- copy running-config startup-config ! ============================================================== !--- Verification: !--- show interfaces trunk -> Gig0/1 desirable, Gig0/2 on, native VLAN 999, VLANs 1,10,20,30,99,999 active !--- show dtp -> 1 interface using DTP (G0/1) !--- ping 192.168.99.2 and ping 192.168.99.3 -> S2 and S3 reachable ! ==============================================================
SWITCH S2
! ============================================================== !--- 3.5.5 Packet Tracer - Configure DTP !--- ANSWER SCRIPT FOR SWITCH S2 !--- Usage: copy this whole file and paste it into the S2 terminal (start at the S2> prompt). Every line beginning with "!" is a comment; IOS ignores it, so pasting a comment by accident is harmless. !--- VLANs 99 and 999 and the VLAN 99 SVI are preconfigured. ! ============================================================== enable configure terminal ! -------------------------------------------------------------- !--- Part 2: Create additional VLANs on S2 and S3. ! -------------------------------------------------------------- !--- Create VLAN 10 Red, VLAN 20 Blue and VLAN 30 Yellow. vlan 10 name Red exit vlan 20 name Blue exit vlan 30 name Yellow exit ! -------------------------------------------------------------- !--- Part 3: Assign VLANs to Ports. ! -------------------------------------------------------------- !--- F0/1 - 8 to VLAN 10, F0/9 - 16 to VLAN 20, F0/17 - 24 to VLAN 30 (access ports). interface range fastethernet 0/1 - 8 switchport mode access switchport access vlan 10 exit interface range fastethernet 0/9 - 16 switchport mode access switchport access vlan 20 exit interface range fastethernet 0/17 - 24 switchport mode access switchport access vlan 30 exit ! -------------------------------------------------------------- !--- Part 4: Configure Trunks on S1, S2, and S3. ! -------------------------------------------------------------- !--- g. G0/1 stays dynamic auto (S1 is desirable) and uses native VLAN 999. interface gigabitethernet 0/1 switchport mode dynamic auto switchport trunk native vlan 999 exit end ! -------------------------------------------------------------- !--- Save the configuration to NVRAM. (Press Enter when prompted for the destination filename.) ! -------------------------------------------------------------- copy running-config startup-config ! ============================================================== !--- Verification: !--- show vlan brief -> Fa0/1-8 VLAN 10, Fa0/9-16 VLAN 20, Fa0/17-24 VLAN 30 !--- show interfaces trunk -> Gig0/1 auto, trunking, native VLAN 999 ! ==============================================================
SWITCH S3
! ============================================================== !--- 3.5.5 Packet Tracer - Configure DTP !--- ANSWER SCRIPT FOR SWITCH S3 !--- Usage: copy this whole file and paste it into the S3 terminal (start at the S3> prompt). Every line beginning with "!" is a comment; IOS ignores it, so pasting a comment by accident is harmless. !--- VLANs 99 and 999 and the VLAN 99 SVI are preconfigured. ! ============================================================== enable configure terminal ! -------------------------------------------------------------- !--- Part 2: Create additional VLANs on S2 and S3. ! -------------------------------------------------------------- !--- d. Create VLAN 10 Red, VLAN 20 Blue and VLAN 30 Yellow. vlan 10 name Red exit vlan 20 name Blue exit vlan 30 name Yellow exit ! -------------------------------------------------------------- !--- Part 3: Assign VLANs to Ports. ! -------------------------------------------------------------- !--- F0/1 - 8 to VLAN 10, F0/9 - 16 to VLAN 20, F0/17 - 24 to VLAN 30 (access ports). interface range fastethernet 0/1 - 8 switchport mode access switchport access vlan 10 exit interface range fastethernet 0/9 - 16 switchport mode access switchport access vlan 20 exit interface range fastethernet 0/17 - 24 switchport mode access switchport access vlan 30 exit ! -------------------------------------------------------------- !--- Part 4 and Part 5: Trunk to S1. ! -------------------------------------------------------------- !--- Part 4g: static trunk with native VLAN 999. Part 5b: disable DTP to match S1 G0/2. interface gigabitethernet 0/2 switchport mode trunk switchport trunk native vlan 999 switchport nonegotiate exit end ! -------------------------------------------------------------- !--- Save the configuration to NVRAM. (Press Enter when prompted for the destination filename.) ! -------------------------------------------------------------- copy running-config startup-config ! ============================================================== !--- Verification: !--- show interfaces trunk -> Gig0/2 on, 802.1q, native VLAN 999 !--- show interfaces gigabitethernet 0/2 switchport -> Negotiation of Trunking: Off !--- From PC1 ping PC6, PC2 ping PC5, PC3 ping PC4 -> successful ! ==============================================================
