How to solve 1002 1005 5

introduction

This document shows how to create a Switch-to-Switch Inter-Switch Link (ISL) trunk. Trunk ports allow connections between switches to carry traffic from more than one VLAN. If trunking is not activated, only the data traffic of the VLAN that you have configured on the port is transmitted over the connection between the two switches. Trunking is not required in very simple switch networks with only one VLAN (broadcast domain). In most LANs, a small portion of the traffic consists of special protocols that manage the network. (Some examples of these are Cisco Discovery Protocol [CDP], VLAN Trunk Protocol [VTP], Dynamic Trunking Protocol [DTP], Spanning Tree Protocol [STP], and Port Aggregation Protocol [PAgP].) They use the Management VLAN too, though You ping or set up a Telnet directly to or from the switch. (If you are using Catalyst OS [CatOS], define the VLAN and IP address of the switch when you configure the sc0 interface. The CatOS Step-by-Step section of this document explains this process.) In a multiple VLAN environment Many network administrators advocate restricting this management traffic to a single VLAN. The VLAN is typically VLAN 1. The administrators then configure user traffic to flow in VLANs other than this standard VLAN. ISL (Cisco proprietary) is one of two possible trunking protocols for Ethernet. The other protocol is the IEEE 802.1Q standard.

This document describes the procedure for configuring ISL trunking between the Catalyst 5500/5000 and 6500/6000 series switches. The CatOS configuration applies to Catalyst switches of the 5500/5000 and 6500/6000 series. However, you can only apply the Cisco IOS® software configuration to the Catalyst 6500 and 6000 series switches.

requirements

conditions

There are no special requirements for this document.

Components used

The information in this document is based on the following software and hardware versions:

  • at least one terminal.

  • At least one console cable suitable for the supervisor engine in your switches. (For more information, see the Connecting a Terminal to the Console Port on Catalyst Switches document.)

  • two Catalyst 5500/500 or Catalyst 6500/6000 switches (with CatOS) or two Catalyst 6500/6000 switches (with Cisco IOS software) in a laboratory environment1 with released configurations2.

  • two ethernet interfaces that can support ISL.

  • a 10BASE-T crossover cable.

1 The information in this document was produced by the devices in a specific laboratory environment. All devices used in this document started with an empty (standard) configuration. With your network up and running, make sure you understand the potential implications of a command.

2 With CatOS the command clear config all ensures that a standard configuration is in place. For the Cisco IOS software, the configuration was done using the command write erase deleted.

Conventions

For more information on document conventions, see the Cisco Technical Tips Conventions.

Creation of a switch-to-switch ISL trunk

Switches A and B in this topology represent either two Catalyst 5500/5000 switches with CatOS or two Catalyst 6500/6000 switches running the Cisco IOS software.

By default, switches A and B have 2/1 ports in VLAN 1. This configuration allows data traffic from other ports in VLAN 1 between the switches without having to configure trunking. References to "the management VLAN" apply to VLAN 1.

Note: VLAN 1 is the standard VLAN for all types of Ethernet interfaces as well as FDDI. VLAN 1 is also the default VLAN for the management interface (sc0).

In the following example you have configured ports 2/2 on both switches in VLAN 2. The traffic from devices that you have connected to the ports in VLAN 2 does not cross the connection between the switches. Therefore PCs A and B cannot communicate.

The solution is to enable ISL trunking for the connection between switches A and B. With trunking, a VLAN header is added to each frame during transmission (multiplex) to a trunk connection. This allows the switch at the other end of the connection to demultiplicate the frames. The switch then forwards the frames to the corresponding VLAN ports.

tasks

These steps will guide you through this configuration:

  1. Connect a terminal to the switches.

  2. Check the ISL support on the ports.

  3. Connect the switches.

  4. Check that the ports are operational.

  5. Assign IP addresses to the management ports.

  6. Make sure that the switches are not routed over the link.

  7. Ping from switch to switch.

  8. Create a VLAN 2 in each switch.

  9. Move the management interface (sc0) to VLAN 2 (for CatOS).

  10. Make sure that a ping connection between switches is not possible.

  11. Configure the same VTP domain name on each switch.

  12. Enable trunking between the switches.

  13. Verify that the switches are bundled over the link.

  14. Ping from switch to switch.

Step-by-step instructions for CatOS

Follow these steps:

  1. Connect a terminal to the console ports on the switches.

    Further information can be found in this document:

  2. Make sure the ports you have chosen support ISL trunking.

    There are several types of Ethernet interfaces that support ISL trunking. The 10BASE-T (shared Ethernet) ports do not support trunking, while most 100BASE-T (Fast Ethernet) ports support trunking.

    Set the show port functions module_number.Module_number / port_number command on both switches to determine if the ports you are using support ISL.

    Note: In this example the command specifies the port identifier. This limits the answer to the information that is directly applicable.

    cat5000> (enable) show port capabilities 2/1 Model WS-X5234 Port 2/1 Type 10 / 100BaseTX Speed ​​auto, 10,100 Duplex half, full Trunk encap type 802.1Q,ISLTrunk mode on, off, desirable, auto, nonegotiate Channel 2 / 1-2,2 / 1-4 Broadcast suppression percentage (0-100) Flow control receive- (off, on), send- (off, on) Security yes Membership static, dynamic Fast start yes QOS scheduling rx- (none), TX (1q4t) COs rewrite yes ToS rewrite IP-Precedence Rewrite yes UDLD yes AuxiliaryVlan 1..1000,1025..4094, untagged, dot1p, none SPAN source, destination
  3. Connect the two switch ports with the Ethernet crossover cable.

    In this example the switch A 2/1 port is connected to the switch B 2/1 port.

  4. To verify that the ports are operational, run the command show port 2/1 on switch A.

    Switch-A> (enable) show port 2/1 Port Name Status VLAN Level Duplex Speed ​​Type ----- ------------------ ---------- --------- - ------ ------ ----- ------------ 2/1 connected 1 normal a-full a-100 10 / 100BaseTX Switch-A> ( enable)
  5. Give the command set interface sc0 172.16.84.17 255.255.255.0 172.16.84.255 on switch A and the Set interface sc0 172.16.84.182 a. command 55.255.255.0 172.16.84.255 on switch B.

    These commands assign IP addresses from the same subnet to the management ports on both switches. You may also need to specify the VLAN for sc0 (the management VLAN) in the command. Add this VLAN if the VLAN deviates from the standard (VLAN 1).

    Switch-> (enable) set interface sc0 172.16.84.17 255.255.255.0 172.16.84.255 Interface sc0 IP address, netmask, and broadcast set. Switch-A> (enable)

    When you use the show interfaces output from your Cisco device, you can use the Output Interpreter Tool View (registered customers only) potential issues and fixes.

  6. Run the command show trunk 2/1 on switch A to check whether the connection between switches A and B is not trunked.

    Switch-A> (enable) show trunk 2/1 Port Mode Encapsulation Status Native VLAN -------- ----------- ------------- ------------ ----------- 2/1 auto isl not-trunking 1 port VLANs allowed on trunk -------- ----------------- -------------------------------------------------- - 2/1 1-1005 Port VLANs allowed and active in management domain -------- -------------------------- ------------------------------------------- 2/1 1 port VLANs in spanning tree forwarding state and not pruned -------- ----------------------------------- ---------------------------------- 2/1 1 Switch-A> (enable)

    Note: The term in this edition indicates the VLAN placement of this port when the port is not in trunking mode. If you configured the port for 802.1Q trunking, the field also indicates the VLAN for which the frames are not tagged. all others have tags. (With ISL trunking, however, each data frame has the corresponding VLAN ID.)

    The trunking status should be as is the default mode for the DTP. DTP is the strategic replacement for Dynamic ISL (DISL) because DTP includes support for 802.1Q trunking negotiations. DTP is available in Catalyst Software 4.x and higher and in certain hardware modules. DTP can be configured in five different modes. Cisco technical support recommends configuring the desirable trunking mode on the ports of the trunk connection. Step 12 covers this information in more detail.

  7. Ping switch B from switch A to verify that the switches can communicate over the link.

    Switch-A> ping 172.16.84.18 172.16.84.18 is alive Switch-A>
  8. Enter the command to create VLAN 2 in switch A. set vlan 2 on switch A.

    Switch B learns more about VLAN 2 after setting up the VTP domain in step 11.

    Switch-A> (enable) set vlan 2 Vlan 2 configuration successful Switch-A> (enable)
  9. Move the management interface in switches A and B to VLAN 2 that you created in step 8.

    To change the interface, issue the command set interface sc0 2 a. This output shows the problem with the command on Switch A:

    Switch-A> (enable) set interface sc0 2 Interface sc0 vlan set. Switch-A> (enable)

    Give the command show interfaces to see the changes you just made. This output shows the problem with the command on switch A. The output shows the new link between interface sc0 and VLAN 2:

    Switch-A> (enable) show interfaces sl0: flags = 51 slip 0.0.0.0 dest 0.0.0.0 sc0: flags = 63 vlan 2 inet 172.16.84.17 netmask 255.255.255.0 broadcast 172.16.84.255 Switch-A> (enable)
  10. Try pinging Switch B from Switch A.

    The ping command should fail because the management ports are now in VLAN 2 while the connection between the switches is in VLAN 1.

    Switch-A> (enable) ping 172.16.84.18 no answer from 172.16.84.18 Switch-A> (enable)
  11. Set up the same VTP domain for both switches.

    Give the command set vtp domain cookbook on both switches.

    Note: The name of the VTP domain is Cookbook.

    Switch-A> (enable) set vtp domain cookbook VTP domain Cookbook modified Switch-A> (enable)

    When you get the output of a command show vtp domain from your Cisco device, you can use the Output Interpreter Tool Use (registered customers only) to view potential issues and fixes.

  12. Enable trunking between the switches.

    To configure port 2/1 on switch A for desirable mode, run the command set trunk 2/1 desirable isl on switch A. Switch B is in automatic mode. Switch B automatically sets port 2/1 to trunking mode after the DTP negotiation between the two switches has been completed.

    Note: TheCisco Technical Support recommends configuring the desirable trunking mode on the trunk connection ports.

    Switch-A> (enable) set trunk 2/1 desirable isl Port (s) 2/1 trunk mode set to desirable. Port (s) 2/1 trunk type set to Isl. Switch-A> (enable)

    When you get the output of a command show trunk from your Cisco device, you can use the Output Interpreter Tool Use (registered customers only) to view potential issues and fixes.

    This list describes the five different states for which you can configure DTP:

    • Automobile: The port monitors DTP frames from the neighboring switch. When the neighbor switch indicates that the switch wants to be a trunk or that the switch is a trunk, the automatic state creates the trunk with the neighbor switch. The automatic status does not convey any intention to become a trunk. The automatic status for the trunking decision depends exclusively on the neighboring switch.

    • he wishes: DTP is spoken to the neighboring switch to which you want to set up an ISL trunk. The switch with the desired configuration communicates that the switch can be an ISL trunk and the neighboring switch should also be an ISL trunk. Cisco technical support recommends configuring the desirable trunking mode on the ports of the trunk connection.

    • at the: DTP is spoken to the neighboring switch. The on state automatically activates ISL trunking on the port, regardless of the state of the neighboring switch. The port remains an ISL trunk unless the port receives an ISL packet that explicitly deactivates the ISL trunk.

    • do not negotiate: DTP is not spoken to the neighboring switch. The "Do not negotiate" status automatically activates ISL trunking on the port, regardless of the status of the neighboring switch.

    • Out: No ISL may be used on this port, regardless of the configuration of the DTP mode on the other switch port.

    This table shows the 15 possible, unique combinations of DTP modes. The table also shows whether the combinations result in an active bidirectional trunk. In theory, you can trunking on one connection in one direction rather than the other, but you shouldn't be doing this type of trunking.

    Switch A port / interface 2/1 Switch B port / interface 2/1 ISL trunk status
    Auto in DTP mode Auto in DTP mode Not trunking
    DTP mode desirable Auto in DTP mode Trunking
    DTP mode activated Auto in DTP mode Trunking
    Not negotiating the DTP mode Auto in DTP mode Not trunking
    DTP mode deactivated Auto in DTP mode Not trunking
    DTP mode desirable (Cisco technical support recommended configuration) DTP mode desirable (Cisco Technical Support recommended configuration) Trunking
    DTP mode activated DTP mode desirable Trunking
    Not negotiating the DTP mode DTP mode desirable Not trunking
    DTP mode deactivated DTP mode desirable Not trunking
    DTP mode activated DTP mode activated Trunking
    Not negotiating the DTP mode DTP mode activated Trunking
    DTP mode deactivated DTP mode activated Not trunking
    Not negotiating the DTP mode Not negotiating the DTP mode Trunking
    DTP mode deactivated Not negotiating the DTP mode Not trunking
    DTP mode deactivated DTP mode deactivated Not trunking

    You may see other messages related to changes in STP status on the switch. These messages are not relevant for this document. For more information about this protocol, see Understanding and Configuring Spanning Tree Protocol (STP) on Catalyst Switches (Understanding and Configuring Spanning Tree Protocol (STP) on Catalyst Switches). Since you have deleted the configurations in the switches to be started, you have the default values ​​for the STP parameters. The standard parameters of STP should provide the connectivity necessary for the success of this document.

  13. Enter the command to check the trunk connection show trunk 2/1 at the Switch A prompt.

    Switch-A> (enable) show trunk 2/1 Port Mode Encapsulation Status Native VLAN -------- ----------- ------------- ------------ ----------- 2/1 desirable isl trunking 1 port VLANs allowed on trunk -------- ------------------- -------------------------------------------------- 2/1 2.1002-1005 Port VLANs allowed and active in management domain -------- -------------------------- ------------------------------------------- 2/1 2.1002- 1005 port VLANs in spanning tree forwarding state and not pruned -------- ------------------------------- -------------------------------------- 2/1 2.1002-1005 Switch-A> (enable)

    You should now see that trunking is active.

    Note: VLANs 1-1005 are allowed for all trunk ports by default. You can delete VLAN 1 from the list of permitted VLANs. If you remove VLAN 1 from a trunk, management traffic will continue to be sent and received over the trunk interface, e.g. B. CDP, VTP, PAgP and DTP in VLAN 1. You cannot remove VLANs 1002-1005. In CatOS versions prior to 5.4 (x) you cannot remove VLAN 1 from the trunk.

    To restrict the VLANs on a trunk in CatOS, delete them. Give the command clear trunk 2/1 1-1001 a. To set up the permitted VLANs on the trunk, enter the command set trunk 2/1 2 on switch A.

    Switch-A> (enable) clear trunk 2/1 1-1001 Removing Vlan (s) 1-1001 from allowed list. Port 2/1 allowed vlans modified to 4.Switch-A> (enable) Switch-A> (enable) set trunk 2/1 2 Adding vlans 2 to allowed list. Port (s) 2/1 allowed vlans modified to 5.Switch-A> (enable)

    In this edition, note the authorization to only activate VLANs 1 and 2 for this trunk link:

    Switch-A> (enable) show trunk 2/1 Port Mode Encapsulation Status Native VLAN -------- ----------- ------------- ------------ ----------- 2/1 desirable isl trunking 1 port VLANs allowed on trunk -------- ------------------- -------------------------------------------------- 2/1 1-1005 Port VLANs allowed and active in management domain -------- ---------------------------- ----------------------------------------- 2/1 1-2 port VLANs in spanning tree forwarding state and not pruned -------- ----------------------------------- ---------------------------------- 2/1 1-2 Switch-A> (enable)
  14. Ping Switch B from Switch A to verify that the switches can communicate with each other over the trunk link.

    Switch-A> ping 172.16.84.18 172.16.84.18 is alive Switch-A>

Correction of errors in the result

Commands to use to troubleshoot CatOS

  • show port functions mod / port (show port mode / port) - To view the physical status of a port and port functions.

  • show trunk mod / port: To show trunking information for a specific port.

  • show vtp domain - How to view VTP information.

  • show vlan vlan_number: To display information about a specific VLAN.

  • show spantree vlan_number: To show the status of the spanning tree for a specific VLAN.

  • show interfaces - How to display the configuration of sc0 and sl0.

  • ping - How to send an Internet Control Message Protocol (ICMP) echo message to another IP host.

Note: In switches with multiple interfaces and VLANs, specify the module / port or VLAN number with the command show to restrict the command output. Use of ? Argument with showCommands shows which commands the use of the mod / port arguments allow. For example show trunk? indicates that show trunk mod / port allowed is.

Step-by-step instructions for the Cisco IOS software

Follow these steps:

  1. Connect a terminal to the console ports on the switches.

    Further information can be found in this document:

  2. Make sure the ports you have chosen support ISL trunking.

    There is currently no command available to view the module or port functions of the Cisco IOS software. All Ethernet modules of the type 10 / 100BASE-T, 1000BASE-TX, 100BASE-FX and 1000BASE-SX / LX / ZX for the Catalyst switches of the 6500/600 series support ISL trunking.

    Note: The 10 Gigabit Ethernet Switching Module (WS-X6501-10GEX4) does not support ISL encapsulation.

  3. Connect the two switch ports with the Ethernet crossover cable.

    In this example the switch A 2/1 port is connected to the switch B 2/1 port.

  4. To verify that the ports are operational, run the command show interfaces fastethernet 2/1 status off.

    The command displays the following information:

    Switch-A # show interfaces fastethernet 2/1 status Port Name Status VLAN Duplex Speed ​​Type Fa2 / 1 connected 1 a-full a-100 10 / 100BaseTX Switch-A #
  5. Configure a VLAN interface on both switches A and B.

    Enter the command in the global configuration mode interface vlan 1. When you configure the IP address, issue the command ip address 172.16.84.17 255.255.255.0 on switch A and the IP address 172.16.84.17 255.255.0. on switch B. To configure switch port 2/1 as a layer 2 interface (L2) and a member of VLAN 1, enter the commands interface fastethernet 3/1, switchport and switchport access vlan 1. For more information on configuring L2 interfaces in the Cisco IOS software, see this document:

    Switch-A (config) # interface vlan 1 Switch-A (config-if) # ip address 172.16.84.17 255.255.255.0 Switch-A (config-if) # Switch-A (config) # interface fastethernet 2/1 Switch-A (config-if) # switchport Switch-A (config-if) # switchport access vlan 1 Switch-A (config-if) #
  6. Run the command show interfaces fastethernet 2/1 trunkto check that the connection between switches A and B is not trunked.

    Switch-A # show interfaces fastethernet 2/1 trunk Port Mode Encapsulation Status Native VLAN Fa2 / 1 desirable negotiate not-trunking 1 Port VLANs allowed on trunk Fa2 / 1 none Port VLANs allowed and active in management domain Fa2 / 1 none Port VLANs in spanning tree forwarding state and not pruned Fa2 / 1 none Switch-A #

    Note: The term in this edition indicates the VLAN placement of this port when the port is not in trunking mode. If you configured the port for 802.1Q trunking, the field also indicates the VLAN for which the frames are not tagged. all others have tags. (With ISL trunking, however, each data frame has the corresponding VLAN ID.)

  7. Ping switch B from switch A to verify that the switches can communicate over the link.

    Switch-A> ping 66.123.210.122 Type escape sequence to abort. Sending 5, 100-byte ICMP echoes to 172.16.84.18, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min / avg / max = 4/21/92 ms Switch-A>
  8. To create VLAN 2 in Switch A, issue the command vlan database and the command vlan 2 on switch A.

    Switch B learns more about VLAN 2 after setting up the VTP domain in step 11. For more information on configuring VLANs in the Cisco IOS software code, see this document:

    • Configuring VLANs

      Switch-A # vlan database Switch-A (vlan) # vlan 2 VLAN 2 added: Name: VLAN0002 Switch-A (vlan) #exit APPLY completed. Exiting .... Switch-A #
  9. Move the management interface on switches A and B to VLAN 2 that you created in step 8.

    There is no sc0 management interface in Cisco IOS software mode. Therefore, configure the ports connected to host A on switch A and host B on switch B for VLAN 2. Enter the commands switchport and switchport access vlan 2. Then use the hosts to perform the ping tests. In this example, configure the IP addresses 172.16.85.1/24 on host A and 172.16.85.2/24 on host B.

    Switch-A (config) # interface fastethernet 2/2 Switch-A (config-if) # switchport Switch-A (config-if) # switchport access vlan 2

    Give the command show interfaces to see the changes you just made. This output shows the problem with the command on switch A. The output shows the new assignment of interface 2/2 and VLAN 2:

    Switch-A # show interfaces fastethernet 2/2 switchport Name: Fa2 / 2 Switchport: Enabled Administrative Mode: dynamic desirable Operational Mode: up Administrative Trunking Encapsulation: negotiate Negotiation of Trunking: On Access Mode VLAN: 2 (VLAN0002) Switch-A # show interfaces fastethernet 2/2 switchport Name: Fa2 / 2 Switchport: Enabled Administrative Mode: dynamic desirable Operational Mode: up Administrative Trunking Encapsulation: negotiate Negotiation of Trunking: On Access Mode VLAN: 2 (VLAN0002) ! --- Output suppressed.
  10. Try pinging the host connected to the alternate switch.

    The ping command should fail because the ports are now in VLAN 2 while the connection between the switches is in VLAN 1.

    C: \> ping 172.16.85.1 Pinging 172.16.85.1 with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for 172.16.85.1: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms C: \>
  11. Set up the same VTP domain for both switches.

    Give the command vtp domain cookbook in global configuration mode.

    Note: The name of the VTP domain is Cookbook.

    For more information on configuring VTP parameters using the Cisco IOS software, see this document:

    • Configuring VTP

      Switch-A (config) # vtp domain cookbook Changing VTP domain name from NULL to cookbook Switch-A (config) #
  12. Enable trunking between the switches.

    Configure port 2/1 on switch A for desirable mode. To configure the encapsulation type and mode, issue the command switchport trunk encapsulation isl and the command switchport mode dynamic wishes a. Switch B is in automatic mode. Switch B automatically sets port 2/1 to trunking mode after the DTP negotiation between the two switches has been completed.

    Note: TheCisco Technical Support recommends configuring the desirable trunking mode on the trunk connection ports.

    Switch-A (config) # interface fastethernet 2/1 Switch-A (config-if) # switchport trunk encapsulation isl Switch-A (config-if) # switchport mode dynamic desirable

    This list describes the five different states for which you can configure DTP:

    • Automobile: The port monitors DTP frames from the neighboring switch. When the neighbor switch indicates that the switch wants to be a trunk or that the switch is a trunk, the automatic state creates the trunk with the neighbor switch. The automatic status does not convey any intention to become a trunk. The automatic status for the trunking decision depends exclusively on the neighboring switch.

    • he wishes: DTP is spoken to the neighboring switch to which you want to set up an ISL trunk. The switch with the desired configuration communicates that the switch can be an ISL trunk and the neighboring switch should also be an ISL trunk.

    • at the: DTP is spoken to the neighboring switch. The on state automatically activates ISL trunking on the port, regardless of the state of the neighboring switch. The port remains an ISL trunk unless the port receives an ISL packet that explicitly deactivates the ISL trunk. Cisco Technical Support recommends configuring the desirable trunking mode for the ports.

    • do not negotiate: DTP is not spoken to the neighboring switch. The "Do not negotiate" status automatically activates ISL trunking on the port, regardless of the status of the neighboring switch.

    • Out: No ISL may be used on this port, regardless of the configuration of the DTP mode on the other switch port.

    This table shows the 15 possible, unique combinations of DTP modes. The table also shows whether the combinations result in an active bidirectional trunk. In theory, you can trunking on one connection in one direction rather than the other, but you shouldn't be doing this type of trunking.

    Switch A port / interface 2/1 Switch B port / interface 2/1 ISL trunk status
    Auto in DTP mode Auto in DTP mode Not trunking
    DTP mode desirable Auto in DTP mode Trunking
    DTP mode activated Auto in DTP mode Trunking
    Not negotiating the DTP mode Auto in DTP mode Not trunking
    DTP mode deactivated Auto in DTP mode Not trunking
    DTP mode desirable (Cisco Technical Support recommended configuration) DTP mode desirable (Cisco Technical Support recommended configuration) Trunking
    DTP mode activated DTP mode desirable Trunking
    Not negotiating the DTP mode DTP mode desirable Not trunking
    DTP mode deactivated DTP mode desirable Not trunking
    DTP mode activated DTP mode activated Trunking
    Not negotiating the DTP mode DTP mode activated Trunking
    DTP mode deactivated DTP mode activated Not trunking
    Not negotiating the DTP mode Trunking Trunking
    DTP mode deactivated Not negotiating the DTP mode Not trunking
    DTP mode deactivated DTP mode deactivated Not trunking

    You may see other messages related to changes in STP status on the switch. These messages are not relevant for this document. For more information about this protocol, see Understanding and Configuring Spanning Tree Protocol (STP) on Catalyst Switches (Understanding and Configuring Spanning Tree Protocol (STP) on Catalyst Switches). Since you have deleted the configurations in the switches to be started, you have the default values ​​for the STP parameters. The standard parameters of STP should provide the connectivity necessary for the success of this document.

  13. To check the trunk, run the command show interfaces fastethernet 2/1 trunk.

    Switch-A # show interfaces fastethernet 2/1 trunk Port Mode Encapsulation Status Native VLAN Fa2 / 1 desirable isl trunking 1 Port VLANs allowed on trunk Fa2 / 1 1-1005 Port VLANs allowed and active in management domain Fa2 / 1 1-2,1002-1005 Port VLANs in spanning tree forwarding state and not pruned Fa2 / 1 1-2,1002-1005

    You should now see that trunking is active.

    Note: VLANs 1-1005 are allowed for all trunk ports by default. You can delete VLAN 1 from the list of permitted VLANs. If you remove VLAN 1 from a trunk, management traffic will continue to be sent and received over the trunk interface, e.g. B. CDP, VTP, PAgP and DTP in VLAN 1.

    In order to limit or remove VLANs on a trunk, the command switchport trunk allowed vlan remove 1-1001 run in interface configuration mode. The command removes all removable VLANs from the trunk. Give the command switchport trunk allowed vlan add 2 to add VLAN 2 to the list of allowed VLANs in the trunk.

    Switch-A (config-if) # switchport trunk allowed vlan remove 1-1001 Switch-A (config-if) # Switch-A (config-if) # switchport trunk allowed vlan add 2 Switch-A (config-if) #

    In this edition, note the authorization of only VLANs 2 and 1002-1005 on the trunk:

    Switch-A # show interfaces fastethernet 2/1 trunk Port Mode Encapsulation Status Native VLAN Fa2 / 1 desirable isl 2.1002-1005 1 Port VLANs allowed on trunk Fa2 / 1 2.1002-1005 Port VLANs allowed and active in management domain Fa2 / 1 2.1002-1005 Port VLANs in spanning tree forwarding state and not pruned Fa2 / 1 2,1002-1005
  14. To verify that the trunk link is active, try pinging the trunk link.

    Ping host A from host B to verify connection over VLAN 2.

    C: \> ping 172.16.85.1 Pinging 172.16.85.1 with 32 bytes of data: Reply from 172.16.85.1: bytes = 32 time <10ms TTL = 255 Reply from 172.16.85.1: bytes = 32 time <10ms TTL = 255 Reply from 172.16.85.1: bytes = 32 time <10ms TTL = 255 Reply from 172.16.85.1: bytes = 32 time <10ms TTL = 255 Ping statistics for 172.16.85.1: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milliseconds: minimum = 0ms, maximum = 0ms, average = 0ms C: \>

Correcting errors in the result

Commands to Use to Troubleshoot Cisco IOS Software

  • show interfaces fastethernet port / mod trunk - How to display the trunking information for a specific interface.

  • show vtp status - How to view VTP information

  • show vlan vlan_number: To display information about a specific VLAN.

  • show spanning-tree vlan vlan_number - To view the status of the spanning tree for a specific VLAN.

  • show interfaces fastethernet port / mod switchport - Information on the L2 interface.

  • ping - How to send an ICMP echo message to another IP host.

Related information