How to configure sg300-10 and VLAN ID can be seen in the wireshark

[lejiajing1208]

Hello, everyone,

I have a question to ask. I brought a new sg300-10 switch. I want to use it to send ethernet packets. I have connected it with my laptop via port1. At the laptop side, I used wireshark to capture. But I didn't find that VLAN ID was shown in the wireshark(I have modified the registry of my laptop, so VLAN ID should be shown if it is contained in the frame). So I think I didn't configure the switch well and the vlan id is not contained in the frame which was sent by swith. Does anyone know how to figure out?

Thanks

[Tom Watts]

Hi Jiajing, an "untagged" VLAN packet should not be seen in a Wireshark capture. In order to see the VLAN ID the packet must be tagged.

An example would be-

Host A connects to the switch on VLAN 99 untagged. The switch has an uplink to another switch with a trunk as VLAN 1 untagged, VLAN 99 tagged. The switch uplink is connecting to the router which contains the route table, etc.

If you ran the packet capture on the uplink trunk port and you were utilizing Host A which is VLAN 99 untagged, you should see traffic with the VLAN 99 Tagged.

-Tom
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[lejiajing1208]

Hi Tom,

Thank you for your reply. I tried to set the port which I am using to be VLAN tagged. But I don't know why the web GUI is down when I configure like this.

[Tom Watts · Accepted solution]

Hi Jiang, if your adminstering computer is connected to port 1, it cannot understand the VLAN tag. That's why it has the appearance the GUI hangs.

-Tom
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[lejiajing1208]

Hi Tom

If I don't connect my laptop to port1, then how can I configure switch via web GUI?

Thanks.

[Tom Watts · Accepted solution]

Jiajing, if you have only the 1 computer and the switch, it is not really viable to test to see if you can see a VLAN ID in a packet.

The VLAN ID will be present only on VLAN tagged traffic. VLAN tags don't usually happen at a host level. Typically the VLAN tag happens at an interconnection of devices such as the switch connecting to another switch or a switch connecting to an IP phone if the phone supports the VLAN tag.

If you set up a port mirror (SPAN) for your computer running wireshark with a source port of that of an uplink that has a VLAN tag specified AND traffic generated there, it would be the most apparent way to capture the VLAN ID.

-Tom
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[lejiajing1208]

Hello Tom,

I got it, thank you very much!!