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802.1q trunking between 4006 and 3com 3310 issue

The status is good when we have configured 802.1q trunk between the two switches,but actually it didn't work,for we can not ping each other successfully.Then I config (set dot1q-all-tagged enable) on 4006 and it worked well.I am confused about it,I checked the 3com switch and find that vlan 1 is a native vlan,which is just like the 4006.Why must we enable the native vlan tag for the trunk?There is not any similar commond in 3com switch.

2 REPLIES

Re: 802.1q trunking between 4006 and 3com 3310 issue

Hi,

it seems like 3Com does configure 802.1q following way:

VLAN1 is default on each port and not tagged. When you create another VLAN on a switch port, you choose a tagging type. Only one VLAN per port can be untagged (VLAN1 default) but you can change all VLANs to tagged (which probably happened in your case).

IEEE 802.1q says there might be untagged frames on the trunk and depending on vendor implementation they are either considerd as one VLAN (this VLAN can't use tagged frames then) or discarded.

"Native VLAN" is a Cisco proprietary term.

Following is an output from 3Com Knowledgebase (the important ifno is near the end of it):

Title:SuperStack II Switch 1100/3300 - 802.1q VLAN Tagging

ID:2.0.31670123.2633250

Domain:primus_owner

Solution Statements

Problem: How To Set Up 802.1q Tagging

Fact: SuperStack II Switch 3300

Fact: SuperStack II Switch 1100

Fact: 802.1q

Fact: VLAN

Fact: CLI

Fact: Command Line Interface

Fix: VLAN options are only available in the CLI of the SuperStack II Switch 1100/3300 in v2.2 of the firmware and above. Commands in the CLI can be abbreviated.

Fix: The Switch can be administered via the Default VLAN. It is therefore recommended that the user sets up a connection via the Console Port on the Switch to setup VLANs. If the user is trying to administer VLANs through a Telnet connection or via the Web Interface, and they remove their port from the Default VLAN, they will lose all access to the administrative functions of the Switch.

Fix: Configuring VLANs:

Create the VLAN:

A. From the main menu, type BR VL and press ENTER (Alternatively, the user can choose BRIDGE then VLAN)

B. From the Bridging/VLAN menu, type CR and press ENTER (Alternatively the user can choose CREATE)

C. The Switch will prompt you for the VLAN ID (2-4094). This corresponds to the 802.1q VLAN ID field in the Web Interface and is considered the Network VLAN ID. The number 1 is not available, because it is the Default VLAN, and is already configured.

1. Type in the number in use on your network for the VLAN you are attempting to map and press ENTER

D. The Switch will prompt you for the Local ID (2-16). This corresponds to the Local ID listbox in the Web Interface. It is NOT global to the network. The number 1 is not available, because it is the Default VLAN, and is already configured

1. Type in the number you would like to use locally, and press ENTER

E. The Switch will prompt you for a VLAN name. Type in a name you would like to use, and press ENTER

F. Assign ports to the VLAN:

1. From the Bridging/VLAN menu, type ADD and press ENTER (Alternatively, the user can choose ADDPORT)

2. The Switch will prompt you for a VLAN ID. Enter the VLAN ID / Network VLAN ID from Step I.C. above. This is NOT the Local ID.

3. The Switch will prompt you to select the Ethernet ports you would like to add to this VLAN. You can add individual ports by typing their port number and pressing ENTER. Note: You can add ALL ports by typing ALL and pressing ENTER

4. The Switch will prompt you to enter a TAG TYPE. Type NONE and press ENTER to make this port a member of an UNTAGGED VLAN. This is necessary if the device connected to this port is not capable of 802.1q tagging. Each port can ONLY be a member of 1untagged VLAN. To add tagged VLANs to this port in addition to the one untagged, repeat the above process, but choose 802.1q for the new Tag Type.

5. Type 802.1q and press ENTER to make this port a member of a TAGGED VLAN. A port can be a member of all tagged VLANs but the device that is connected to this port must support 802.1q tagging. To add another tagged VLAN to this port, repeat the above process.

Fix: When creating a backbone port to another switch, include the port at both ends in all VLANs as 802.1q Tagged. If you need to administrate the Switch across the network, put the Workstation into Default VLAN 1 on the Switch in which it is connected.

Regards,

Milan

New Member

Re: 802.1q trunking between 4006 and 3com 3310 issue

OK thanks for your info.

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