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Hi Everyone,

I have been trying to make 2 switches to connect together in a VLAN, but I wasn’t able to get them to connect. I am hoping if someone can tell me what I am doing wrong here… thanks for your help in advance.

I have a Sonicwall, with interface X5 configured with vLAN50. This port connects to 8 ports HP Switch A. ( i think of it as a central switch). All 8 ports in switch A is untagged for van 50. Link Type is Access. PVID is 50.

2 downlink switches are connect to Switch A. Switch B is a 24 ports HP switches. All ports are untagged for vLAN50, Link type is Access; PVID is 50. If I connect a computer/device to any of the free ports, I get the DHCP with VLAN50 IP just fine.

Switch C is also a 24 ports HP switch. Ports 1-8 are configured with other VLANs. I configured 9-24 with vlan50 untagged, Link type is Access; PVID is 50. (same as Switch B). But for reason I am not getting any IP if I plug in any ports between 9-24.

I am not too verse with networking, and I might be using wrong terms here. Please pardon me for the confusion if there is any.

Thank you

1 Spice up
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Can you share the configuration of switch C? Make sure switch C has vlan 50 on the trunk (uplink) port.

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What model HP switches.

You use the term PVID so I am guessing these are the 3Com ones? like a 1910.

What ports connect switch A and switch C?

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If you configured the Sonicwall port for VLAN 50, the switch port that it is connected to will need to be tagged, not untagged.

In general, and mainly because I have multiple VLANs on each switch, I keep the ports between switches tagged. Only the endpoints connect to untagged ports.

You say that you do not receive DHCP on ports 9-24 on switch C. Where does the DHCP server reside?

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You said Untagged,…you are not using Tagging, which is perfectly fine, I don’t use Tagging either,…therefore the VLAN “name” does not mean anything. The VLAN name is the “tag”.

You have to think of the VLANs as a “group of ports”. You connect a group of ports on one switch to a group of ports on the other switch and they will communicate,…even if one group is called VLAN50 and the other group is called VLAN25. However if you have Ports in more than one group (VLAN) at the same time,…then you have to use Tagging,…and that is where the VLAN names come into play,

If you are not using Frame Tagging then you only need to configure VLANs on the Layer3 Switch (Router). A Firewall can also act as a L3 Switch or as a Router. The downstream switches can be totally VLAN Agnostic and have no VLAN config at all.

When you have a switch port active in more than one VLAN,…let’s say 3 VLANs,…then the first VLAN is the Untagged one and the remaining two are Tagged. One way to think of that is the Untagged is “static” and the Tagged are “dynamic”. The Untagged one can also be thought of as the “default vlan” for that particular port, but do not confuse that with the factory Default_VLAN that is global for the switch, that isn’t the same thing.