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  • #2103175

    VLAN Setup using a Switch

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    by raednashat ·

    Hi there…
    I have a network with real (class c IP addresses) and private ( class A IP addresses).
    I need to separate the traffic of these two
    networks using VLAN technology.I have a switch which supports VLAN.It has 24 ports and can be devided into a maximum of four VLANs( I only need two).
    Can I just set up the switch to have two VLANs with one for each network ( class A & c) ?
    Do I really get two Virtual switches in this case with separate traffic for each ?

    Can I just continue to use my switch while mixing class A & C IP addresses on the same physical segment ( No VLAN ) ? Any Problem with this design ?

    Please try to answer my question ASAP.
    Thanks & best regards.

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    • #3816954

      VLAN Setup using a Switch

      by thuan.nguyen ·

      In reply to VLAN Setup using a Switch

      First, what kind of switch do you currently have?

      Yes, you can create 2 VLANs to separate the traffic of each subnet (Class A & C).

      Additionally, you must have a router setup to route traffic between these VLANS. Without a router, these VLANs will not able to talk to each other.

      Mixing multiple configuration of subnets on a same physical switch without creating VLANs will not work and not reccommended.

      Hope this will help!
      Thuan

    • #3815270

      VLAN Setup using a Switch

      by Anonymous ·

      In reply to VLAN Setup using a Switch

      Setup the VLANs on the switch. Each switch VLAN must have a seperate connection to the router (two ethernet ports to the router, unless you use one trunk port on the switch (recommended). You can only have two different subnets on the switch connected to the router if you have a secondary IP address on the router. This usually works ok…

    • #3758607

      VLAN Setup using a Switch

      by sidney ·

      In reply to VLAN Setup using a Switch

      I would warn against using secondary IPs, they will create routing issues when using dynamic protocols. I.e. there will be split horizon issues. Routing updates will not be passed from the primary to the secondary interface and vice-versa. Sub-interfaces allow you to circumvent that.

      Ideal solution:
      Create two VLANs and populate them with the correct ports. Create one ISL trunk or tagged port to connect to the router (depending on the switch vendor). Configure “encapsultation isl” on the router’s ethernet interface. Create two subinterfaces on the router’s ethernet interface (one for each network). Voila, you should have two isolated VLANs that communicate through the router now.

    • #3722241

      VLAN Setup using a Switch

      by raednashat ·

      In reply to VLAN Setup using a Switch

      This question was closed by the author

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