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Cisco Catalyst 1900 Series Switches

Catalyst 1900 and 2820 FAQ

Document ID: 17062

Updated: Oct 07, 2005

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Is the port administratively disabled?

Make sure the "Port" LED is in port status mode (the Port LED reverts to port status mode after 30 seconds in any other mode). If the Port LED is amber, the port is not forwarding and might be disabled.

To verify that the port is administratively disabled:

  1. From the Main Menu, enter U and the Usage Summary Menu is displayed.
  2. Enter P and the Port Status Report  is displayed.
  3. If the status of the problem port is "Disabled," the port is administratively disabled.
What are the proper cables for this product?
  • 10BaseT port - straight through RJ-45 cable to a router or  workstation, or an Ethernet crossover RJ-45 cable to a hub or another switch (Category 3, 4, or 5 UTP)
  • 100BaseFX port - multimode fiber with a MIC connector (for connections up to 2 km long), or singlemode fiber with an ST connector (for connections longer than 2 km)
  • 100BaseTX - straight through RJ-45 cable to a router or workstation, or an Ethernet crossover RJ-45 cable to a hub or another switch (Category 5 UTP)
  • AUI port - external thick coaxial cable, thin coaxial cable, or fiber optic transceiver
How do I enable the port module?
  1. From the Main Menu, enter P.
  2. At the prompt, specify the problem port and the Port Configuration Menu is displayed.
  3. Enter S.
  4. Enter E.
  5. Press Return.
How do I determine if an IP address is configured on the switch?
  1. From the Main Menu, enter N and the Network Management Menu is displayed.
  2. Enter I and the IP Configuration Menu is displayed.
  3. The current IP address for the domain appears under "Settings."
How do I configure an IP address?
  1. From the Main Menu, enter N and the Network Management Menu is displayed.
  2. Enter I and the IP Configuration Menu is displayed.
  3. Enter I to set the IP address.
  4. Enter S to set the subnet mask.
  5. Enter G to set the default gateway.
  6. If you are using multiple VLANs you are prompted to set the IP address and subnet mask of each one.
How do I check the subnet mask on the switch and reconfigure it?
  1. From the Main Menu, enter N and the Network Management Menu is displayed.
  2. Enter I and the IP Configuration Menu is displayed.
  3. Enter S to set the subnet mask.
Is there a default route on the switch?
  1. From the Main Menu, enter N and the Network Management Menu is displayed.
  2. Enter I and the IP Configuration Menu is displayed.
  3. The current gateway setting appears under "Settings."
How do I set a default route on the switch?
  1. From the Main Menu, enter N and the Network Management Menu is displayed.
  2. Enter I and the IP Configuration Menu is displayed.
  3. Type G.
  4. Enter the default gateway address.
  5. Press Return.
What VLAN configuration documents exist on CCO?

Virtual LANs

Are the switch ports to which the end devices connect in the same VLAN?

To check VLAN configurations, follow the steps in the Verifying the Grouping of Switch Ports section of the Virtual LANs document.  Both ports you are trying to connect across must be assigned to the same VLAN.

How do I assign both ports to the same VLAN?

To check VLAN configurations, follow the steps in the Verifying the Grouping of Switch Ports section of the Virtual LANs document. Both ports you are trying to connect across must be assigned to the same VLAN.

Are the VLAN or trunk ports configured to pass that VLAN?

To check VLAN configurations, follow the steps in the Verifying the Grouping of Switch Ports section of the Virtual LANs document.

To check which VLANs are enabled on a trunk port:

  1. From the Main Menu, enter V and the Virtual LAN Configuration Menu is displayed.
  2. At the prompt, enter T, the letter of the trunk port.
  3. Press Return and the Trunk Configuration Menu is displayed.
  4. Enter V to list the allowed VLANs on this trunk port.
How do I assign all non-trunk ports along the link to the same VLAN, and configure any trunk ports along the link to pass that VLAN?

To modify port assignments, follow the steps in the Grouping Switch Ports to VLANs section of the Virtual LANs document.  To change which VLANs are enabled on a trunk port:

  1. From the Main Menu, enter V and the Virtual LAN Configuration Menu is displayed.
  2. At the prompt, enter T, the letter of the trunk port.
  3. Press Return and the Trunk Configuration Menu is displayed.
  4. Enter A.
  5. At the prompt, type the VLAN number.
  6. Press Return.
Are all the switch ports along the link between the end device and the router either in the same VLAN or trunk ports configured to pass that VLAN?

To modify port assignments, follow the steps in the Grouping Switch Ports to VLANs section of the Virtual LANs document.  To change which VLANs are enabled on a trunk port:

  1. From the Main Menu, enter V and the Virtual LAN Configuration Menu is displayed.
  2. At the prompt, enter T, the letter of the trunk port.
  3. Press Return and the Trunk Configuration Menu is displayed.
  4. Enter A.
  5. At the prompt, type the VLAN number.
  6. Press Return.
Is the trunk port connected and configured with the correct speed and duplex settings?
  1. From the Main Menu, select Port Configuration.
  2. At the prompt, specify the trunk port.
  3. Press Return.
  4. Check the output in the  "Status of port," row.
  5. Check the output in the "Status of port" ("Module status" on the 2820) and "Full duplex / Flow control" rows.
The status should be "enabled" and the duplex must match on both ends of the trunk.

How do I connect the trunk port and/or correct its speed and duplex configuration?

  1. From the Main Menu, select Port Configuration.
  2. At the prompt, specify the trunk port.
  3. Press Return.
To change the port's duplex setting:
  • At the prompt, enter F.
  • Enter E to enable full-duplex operation.
  • Enter D to disable full-duplex operation.
You cannot change the speed setting of the 100BaseT ports.

Is the trunk port trunking and configured to pass the desired VLAN range?

Configuring trunks on the Catalyst 1900 or 2820 requires using the command line interface.

  1. Enter the show trunk [port] command, where "port" is either "A" or "B," depending on the trunk port in question.
  2. The trunking status should be On.
  3. Enter the show trunk [port] allowed-vlans command.
  4. The output shows the VLAN range or individual VLAN numbers the trunk is configured to carry.
How do I configure trunking and/or the desired VLAN range on the trunk port?

Configuring trunks on the Catalyst 1900 or 2820 requires using the command line interface.

  1. Enter the interface fastethernet [module_#]/[port_#] command to select a Fast Ethernet port to configure for trunking.
  2. Enter the trunk on command to configure the port into permanent ISL trunk mode. The default trunking configuration of Fast Ethernet ports is "auto," so at this point the trunk link should come up. If it does not, check the trunking configuration of the Fast Ethernet port on the other end of the trunk link.
  3. Enter the trunk-vlan [vlan-list] command to select up to ten VLANs for trunk grouping.
How do I disable auto-negotiation and change the speed and/or duplex settings?
  1. From the Main Menu, enter P.
  2. At the prompt, select either Port A or B and the Port Configuration Menu for the 100BaseT ports is displayed.
  3. From the Port Configuration Menu, enter F, the Performance option and the Performance Configuration Menu is displayed.
  4. Enter F, for the Full duplex/Flow control option .
  5. At the prompt, select one of the settings:
    • [1] Full duplex
    • [2] Half duplex
    • [3] Full duplex with flow control
    • [4] Auto-negotiate.
Are all switches in the VTP domain running the same version of VTP?

Catalyst 1900 and 2820 switches only support VTP version 1. Make sure that any Catalyst 5000-series switches in the VTP domain are also running VTP version 1.

Standardize the VTP version running on all switches in the VTP domain.

Catalyst 1900 and 2820 switches only support VTP version 1.  Make sure that any other switches in the VTP domain are also running VTP version 1.

Is the problem switch configured with the correct VTP domain name?

  1. From the Main Menu, enter V and the Virtual LAN Configuration Menu is displayed.
  2. At the prompt, enter N to view the current domain name setting.
The domain name must be the same for all switches in the management domain.

Configure the correct domain name on the problem switch.

  1. From the Main Menu, enter V and the Virtual LAN Configuration Menu is displayed.
  2. At the prompt, enter N to view the current domain name setting.
  3. At the prompt, enter the correct domain name.

Updated: Oct 07, 2005
Document ID: 17062