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Wireless Networks Thread, 3Com VLAN setup without getting cut off in Technical; Has anyone setup VLANs on 3Com 4400 series switches (3C17203) or 4900 SX optical switches (3C17702)? What is the precise ...
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    3Com VLAN setup without getting cut off

    Has anyone setup VLANs on 3Com 4400 series switches (3C17203) or 4900 SX optical switches (3C17702)?

    What is the precise order of instructions to create VLANs and assign them to ports? Do you start at the far end of the network and work back, or start in the centre and work out?

    All my attempts seem to add a VLAN2 seem to cut access on the admin VLAN1, and I have to reset the switch by logging on locally to it or by using the console port.

    Any help is appreciated.

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    We have 4400's and 4900's in at work - I cant remember much about the VLAN setup - but I can look again monday when I'm back at work

    I definitely remember that once I understood what I wanted the VLAN to do it was fairly straight forward

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    I have half a dozen 4400 switches connected by optical fibre in a star formation to a central 4900 SX optical switch. For simplicity, lets just look at two 4400 switches connected to each other via the optical switch.

    To configure a VLAN on the remote 44000 switch, I guess the first thing to do is to set the fibre port on that switch to taggable. As soon as I do this I loose connection capability with the remote switch. Then I set the port on the optical switch that is on the other end of the fibre to taggable.

    The third thing to do is to set the port on the 4900 SX optical switch that connects to my local 4400 switch to taggable. This will probably cut access to the optical switch.

    Finally I set the fibre port on my local 4400 to taggable, and I can connect again to the 4900 SX optical switch and through it to the remote 4400 again. Does all this sound sensible?
    Last edited by diagram; 5th March 2011 at 01:10 AM.

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    Tag both uplink ports with the vlans you want, I don't usually tag my management vlan, i then set both uplink ports to 100F seed/duplex. Then on the edge switch make sure you DG is pointing to your router.

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    OK The sequence is this:

    On all the edge switches (EXCEPT the EDGE SWITCH currently connecting you to the core switch) , set the uplink ports to be tagged and include VLAN1 (the managment VLAN) and other VLANs which you want on the switch.

    Set all the ports on the core switch to tagged and include VLAN1 and other VLANS which will travel through the core switch.

    Finally, on the switch currently connecting you to the LAN, set the uplink port to be tagged and include VLAN1 and any other vlan you need.

    After you have done this you can communicate again with all the switches in the network.

    I don't understand ezzauk's comments: on 3COM equipment links between switches have to either tagged or untagged (and can't be both) so once you decide to use vlans then the management vlan has to be tagged where it passes from switch to switch. Traffic from switch to workstation is untagged

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    this is my standard setup script for older 3com equipment, so should be ok fo 4900 series. swap ip's ports and vlans to suit.


    prot ip interface mod
    1
    man
    172.17.255.12
    255.255.255.0
    1
    prot ip route def 172.17.255.1
    br port lacp 1:49,1:50 enable
    br spann stpstate enable
    br vlan cr 4
    Science
    br vlan cr 100
    Servers-Printers
    br vlan mod add
    100
    1:1-48
    un
    br vlan mod add
    4
    1:49-50
    tag
    br vlan mod add
    100
    1:49-50
    tag



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