What is Switchport encapsulation dot1q?

What is Switchport encapsulation dot1q?

switchport trunk encapsulation dot1q sets the encapsulation mode of the trunk interface to the industry standard 802.1Q. switchport trunk encapsulation isl sets the encapsulation mode of the trunk interface to proprietary ISL.

How do I configure a port on a trunk port?

To enable trunk links, configure the ports on either end of the physical link with parallel sets of commands. To configure a switch port on one end of a trunk link, use the switchport mode trunk command. With this command, the interface changes to permanent trunking mode.

How do I enable trunking negotiation?

Enabling Trunking

  1. Enable the trunk: COS. set trunk mod/port [auto | desirable | on | nonegotiate | off] IOS. (global) interface type mod/port.
  2. Specify the encapsulation method: COS. set trunk mod/port [negotiate | isl | dot1Q] IOS.
  3. (Optional) Specify the native VLAN: COS. set vlan number mod/port. IOS.

Whose trunk encapsulation is auto can not be configured to trunk mode?

Command rejected: An interface whose trunk encapsulation is “Auto” can not be configured to “trunk” mode. This is because you are missing the encapsulation type (likely to be 802.1Q) on that port.

What is ISL and DOT1Q?

ISL and DOT1Q are 2 encapsulation standards supporting Virtual LANs (VLANs) on an Ethernet network. These are the 2 frame tagging protocols that Cisco supports. The tagging protocol can be manually specified on a trunk port, or dynamically negotiated using Cisco’s proprietary Dynamic Trunking Protocol (DTP).

What is DOT1Q Cisco?

802.1q (also known as dot1q) is an IEEE industry standard trunking protocol. Cisco switches supports both ISL (Inter Switch Link – Cisco propietory) and 802.1q. 802.1Q-compliant switch ports can be configured to transmit tagged or untagged frames.

Can a trunk port connect to an access port?

The trunk port basically used to connect between switches; however, the access port is used to connect computer laptops, printers, etc. We cannot extend the data from one switch to another switch, access ports via a trunk port. It can only be extended via the access port of the switch.

How do I enable dynamic trunking protocol?

To enable trunking from a Cisco switch to a device that does not support DTP, use the switchport mode trunk and switchport nonegotiate interface configuration mode commands. This causes the interface to become a trunk but not generate DTP frames.

What is trunk negotiation?

If one side is Auto and another side is Desirable, then it will become trunk iink. Trunk mode will sent a DTP packets, so no matter other side is set to Desirable,or Auto it will become a trunk. Non-Negotiate is where to set it to be trunk but it wont sent a DTP packets (Recommended) – Cisco Prefer.

What does Switchport Nonegotiate mean?

switchport nonegotiate: Prevents the interface from generating DTP frames. You can use this command only when the interface switchport mode is access or trunk. You must manually configure the neighboring interface as a trunk interface to establish a trunk link.

What is a native VLAN?

Native VLAN: The native VLAN is the one into which untagged traffic will be put when it’s received on a trunk port. This makes it possible for your VLAN to support legacy devices or devices that don’t tag their traffic like some wireless access points and simply network attached devices.

Is the switchport trunk encapsulation command supported?

You can use the “show interface switchport” command to confirm the operational trunking encapsulation. ISL is not supported on newer devices.

How to change switchport Trunk Mode to 802.1Q?

Let‟s change it to 802.1Q by using the switchport trunk encapsulation command. As you can see the trunk encapsulation is now 802.1Q. Now I can successfully change the switchport mode to trunk.

Why does 2960 not allow ” switchport trunk ” CLI?

2960 will not allow “switchport trunk encapsulation dot1q” CLI. Newer devices don’t support ISL so you can only run 802.1Q. That means that there is no need for an encapsulation command because only one encapsulation is supported. If the device had support for ISL then you would also have that command.

How to use Dot1q in Cisco router?

Encapsulation Dot1Q Command on CISCO Router/Switch 1 Command 2 Use. Allows you to use a router interface as a trunk port to a switch. 3 Syntax 4 Option. Sets the vlan on the subinterface to act as the native VLAN. 5 Example. In the below example we will configure a basic “router on a stick” configuration.