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Wireless Networks Thread, VLan question in Technical; Hi, I am sure as I get older it gets harder to understand stuff. I am playing with my GSM7224 ...
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    VLan question

    Hi,

    I am sure as I get older it gets harder to understand stuff.

    I am playing with my GSM7224 switch as I want to start using VLANs in school but I am struggling to work out the concepts.

    First off all I want to do is make 2 ports only talk to each other. I have one of these switches down the other end of the school which will relay fibre down to this end so port 23 and 24 will talk to each other and relay traffic but the rest of the ports won't use them.

    So I am just using switching VLans.

    I have created a new VLAN id 2

    I have removed the U (untagging) from ports 1 and 24 to test this concept on VLAN ID 1

    I have put the U on ports 1 and 24 in VLAN ID 2

    I cannot ping anything connected to port 1 now.

    Shouldn't this just work?

    I tried changing the VLANID to 2 on each of these ports too.

    What a sec... this started working but... when I plug anything into the other ports I cannot ping anymore.

    Its very confusing as most of the stuff on the internet seems to be about IOS which I forgot 10 years ago

    Anyone shed some light on what they think I am doing wrong?

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    teejay's Avatar
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    Every port should have 1 untagged VLAN id, it basically means that is the default VLAN traffic from that port will belong to, so on your switch you would have all your ports assigned to the default VLAN, which is usually VLAN 1, except for your two ports which are assigned as untagged to VLAN 2 so all their traffic defaults to VLAN 2.
    If you are running the VLAN between switches, on the uplinks as well as the default untagged VLAN, you set any other VLANS where you want traffic to flow to other switches as tagged VLANs.

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    The GSM7224 is a layer 2 switch so it's unable to route traffic between 2 or more VLANs. If you want devices in 2 VLANS to be able to communicate you will need a router.

    But the basic concept of VLANs is you should put whichever ports that need to pass traffic into the same untagged VLAN.

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    This is weird.

    So.

    By default all ports are untagged.

    I remove the tagging from ports 1 and 24 so they are blank

    I create a new vlan called 2

    I make ports 1 and 24 untagged on vlan id 2

    So ports 1 and 24 should communicate with each other but the other ports can't see them?

    If port 24 is untagged or tagged on vlan2 and the switch I am connecting via is just a dumb switch should it still ping?

    I thought if they were both untagged then traffic would communicate between each of these ports and when its running to another switch and untrunked strip the tagging away

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    Where are you pinging from?

    But if for example you have a laptop connected to port 1 (untagged VLAN2) and the remote switch connected to port 24 (untagged VLAN2) you should be able to ping the remote switch as the remote switch is now essentially in VLAN2.

    I'd avoid tagging the VLAN that is going to the remote switch as that may cause problems.

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    teejay's Avatar
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    So ports 1 and 24 should communicate with each other but the other ports can't see them? - Yep
    If port 24 is untagged or tagged on vlan2 and the switch I am connecting via is just a dumb switch should it still ping? Depends on the dumb switch, it should, yes, but some won't.

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    If I just had ports 1 and 24 plugged in then the laptop at port 1 could ping the network on port 24 when both were on vlan id 2

    As soon as I plugged in another cable into the switch into a port on vlan1 then the laptop failed to get replies from the network.

    I will have to try again tommorow, I don't have any cross over cables so I reckon I need to use the IT suite next door to create a better test bed. I wonder if my little 8 port switch that I was running the network through isn't up to the testing.

    I am a little worried about some of my switches not being up to handling the traffic if I start using vlans. I've been replacing switches with the GSM7224R kit but some on the outskirts are still just bog standard switches.

    Thanks for the help. I am going home to try and figure some more stuff out.

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    Okay so I figured it out and managed to get Vlans working across my switches which is great.

    Only thing I can't figure out is how to manage the switch when its on a different Vlan.

    I assigned port 24 to Vlan2 and took if off Vlan 1.

    I can ping the switch and access the other devices that I have put into Vlan 2 only but I can't get to the webpage... when i plug into a port on Vlan1 it works again.

    Also.. whats the difference between port membership and PVID.. I know the definition differences but I can only get it to work when i change the PVID.

    Reckon when I get this sorted I will be moving some stuff onto VLans... firstly my backup device. Still a bit unsure how you communicate between VLANS... I thought it was just untagging ports on each VLAN.

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