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Running two networks on one infrastructure

Discussion in 'Networks' started by dpbarry, Sep 29, 2008.

  1. dpbarry

    dpbarry Bit Poster

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    Hi folks..

    Possibly a silly question but one I don't know the answer to!!.

    Is it possible to run 2 separate networks with different subnet masks on one cable infrastructure?

    What I'm looking to do is use our existing network infrastructure to hook on another server and a few workstations to experiment in setting up a Windows 2003 server. As the 2k3 server will have DCHP enabled, I don't want it to interfere with the existing network setup (NT4 :oops:)

    Regards

    Declan Barry
     
    Certifications: None at present
    WIP: None at present
  2. zcapr17

    zcapr17 Nibble Poster

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    Declan,

    The typical way to accomplish this is to configure a VLAN for each network on your switches.

    If your switches don't support VLANs then the problem you are going to have is that existing workstations (assuming they are already using DHCP) will get addresses from the new 2k3 DHCP server as DHCP uses broadcasts. In which case you have two alternative options:
    1. Do not use a DHCP server on the test network - use all static IPs.
    2. On the test DHCP server, create a DHCP reservation for every IP address in the scope - this way, only machines with specific MAC addresses will get an IP lease from the test DHCP server.
    HTH

    z.
     
    Certifications: MCSE:2K3 MCTS:Vista VCPv3 ITILv3 Sec+ L+
    WIP: MCITP Enterprise Admin 2008, CCA
  3. MLP

    MLP Kilobyte Poster

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    Hi

    At my place, for historical reasons, we run two separate domains on one cable infrastructure. I.E. We have a "Curriculum" domain, with all workstations set to get a DHCP address, with a 10.12.14*.* IP, and a subnet mask of 255.255.252.0. Our "Admin" domain has all workstations set to static IP, with a 172.30.0.* IP, and a subnet mask of 255.255.255.0. This obviously requires two sets of workstations.

    I'm not sure how practical or reliable this is, but it may be possible to have a DHCP server on each of the two different subnets, using MAC filtering.

    HTH

    Maria
     
    Certifications: HND Computing
    WIP: 70-680, 70-270, 70-290
  4. dpbarry

    dpbarry Bit Poster

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    Cheers Guys..

    I'm going to have a look at both methods described.

    Off the top of my head, I 'think' the 3com 3300 switches support vlan. I'm off to check

    Declan
     
    Certifications: None at present
    WIP: None at present
  5. Sparky
    Highly Decorated Member Award

    Sparky Zettabyte Poster Moderator

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    If it doesn’t you can do this if the switches are not managed. I have a 3COM switch patched into a router with 3 network ports so I can run three subnets for testing. You will have to apply static IPs to your test Windows 2003 network and also make sure you don’t switch on DHCP.

    Also if you don’t have a router you wont be able to browse the web as the main gateway to the tinterweb will be on your Windows NT subnet. You could put two NICs on the Windows 2003 server and run RRAS though if you want two route traffic between the NT and 2003 network.

    Still on NT? Best of luck with the upgrade! :biggrin
     
    Certifications: MSc MCSE MCSA:M MCSA:S MCITP:EA MCTS(x5) Security+ Network+ A+
    WIP: Exchange 2007\2010
  6. dpbarry

    dpbarry Bit Poster

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    From what I can see, 3com 3300 switches do support vlans but I don't think any of my 3COM 3300 switches have a Layer 3 module in them. I am positioned in a different part of the school to where my broadband router is positioned. I have a 3300 in my room which connects to another 3300 via fibre to the servers near the router. As is, with the current setup where the switch ports are available to all, If I set up 2 vlans (one for current network and one for test network), is there a way I can set up both of the vlans in such a way that both can see the router to connect to the Internet even though they are 'seperate' networks?

    Declan
     
    Certifications: None at present
    WIP: None at present
  7. Sparky
    Highly Decorated Member Award

    Sparky Zettabyte Poster Moderator

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    Does the 3COM 3300 in your room have an IP address?
     
    Certifications: MSc MCSE MCSA:M MCSA:S MCITP:EA MCTS(x5) Security+ Network+ A+
    WIP: Exchange 2007\2010
  8. Modey

    Modey Terabyte Poster

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    I think Sparky's sugestion of using a 2k3 server as a router is the easiest to go with. Doesn't actually have to be server class hardware providing it's of a reasonable spec and you can get a couple of network cards in it. I'd be more inclined to do that rather than starting to tinker around with Vlan's on a live network.
     
    Certifications: A+, N+, MCP, MCDST, MCSA 2K3, MCTS, MOS, MTA, MCT, MCITP:EDST7, MCSA W7, Citrix CCA, ITIL Foundation
    WIP: Nada
  9. r.h.lee

    r.h.lee Gigabyte Poster

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    dpbarry,

    What make and model is your "...broadband router...?"
     
    Certifications: MCSE, MCP+I, MCP, CCNA, A+
    WIP: CCDA
  10. dpbarry

    dpbarry Bit Poster

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    Hi Folks..

    Sorry for delay.

    Teh router is a Cisco 1700 Series. It has two network ports at the back. To give a bit of background, we have a managed network system installed here in N. Ireland (C2k). To access the internet, the managed system is plugged into one of the network ports on the router. The legacy system (my NT4 system) is plugged into the other port.

    All works fine as is but I would like to now install a test Windows 2k3 server network (1 server & 2 or 3 workstations)

    I could do it with separate switches without any problems but what I would like is to somehow connect the Win2k3 system onto the legacy system infrastructure and somehow use the same router connection as the legacy system.

    I have 3 - 3Com 3300 switches and can access the management console to change settings on the switches (create vlans etc) but am not sure how to work the vlans in such a way that both can see the router without interfering with each other.

    Apparently if I had a Layer 3 module installed in one of the switches it would be no problem.

    Is it possible if both networks were connected to only one switch rather than 2 (one at my end and one at the server/router end)

    Regards

    Declan
     
    Certifications: None at present
    WIP: None at present
  11. Modey

    Modey Terabyte Poster

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    Well as mentioned previously using a server 2k3 box with 2 NIC's and RRAS would be an easy option. One of the NIC's would connect to the router that you already have, and the other to your new test network. If NAT was set up on the server it would allow clients on the test network to reach the internet, but they wouldn't intefere with your existing NT network.
     
    Certifications: A+, N+, MCP, MCDST, MCSA 2K3, MCTS, MOS, MTA, MCT, MCITP:EDST7, MCSA W7, Citrix CCA, ITIL Foundation
    WIP: Nada
  12. dpbarry

    dpbarry Bit Poster

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    Cheers Folks..

    I'll have a look at it all and give it a go to see what happens

    Declan
     
    Certifications: None at present
    WIP: None at present

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