Extending a T1 over Ethernet / Fiber link

Discussion in 'Cisco' started by Rick G, Jul 11, 2003.

  1. Rick G

    Rick G Guest

    We currently have 2 sites connected via dark fiber with catalyst 3524 and
    GBIC's in trunk mode running multiple VLAN's across. I have a need to
    extend a T1 from one site to the other. I have been trying to find hardware
    to accomplish this, but this of course is "backwards" from the way most
    people would want to do this (most people want to extend the LAN over a T1).
    I had the idea of using 2 Cisco 1601 routers with T1 WIC since they are very
    cheap to pickup and bridging right across them. I tried a design as
    follows:

    Goal: Get circuit from Site A to Site C
    Scenario: Point to Point Site A to Site B. I have fiber / ethernet from
    Site B to Site C

    My idea was to:
    SiteA (router - routed serial interface 192.168.0.1/30) - Site B T1/Jack -
    Cisco 1600 T1 (bridge) - Cisco 1601 Eth (Bridge) - Cat 3524 Vlan 5 - GBIC
    TRUNK FIBER - Cat 3524 Vlan5 - Cisco 1601 Eth (Bridge) - Cisco 1601 T1
    (bridge) - Site C T1/Jack (router - routed serial 192.168.0.2).

    It didn't work. I pulled the VLAN out and put the routers back to back and
    it didn't matter. I litterally want to make the Cisco 1601's dumb pass
    through basically acting as a media converter per se.

    I configured the routers with the following configs:

    Site A - Router with 192.168.0.1 on serial interface

    Site B - Cisco 1601A w/ T1 WIC

    no ip routing
    bridge 1 protocol ieee

    int e0
    desc connected crossover to cisco 1601B
    no ip address
    bridge-group1

    int s0
    shut

    int s1
    desc connected to Site A T1
    no ip address
    bridge-group 1

    === Cross over Ethernet cable or Ethernet VLAN over Fiber Trunk ====

    Site C - Cisco 1601B w/ T1 WIC

    no ip routing
    bridge 1 protocol ieee

    int e0
    desc connected crossover to cisco 1601A
    no ip address
    bridge-group1

    int s0
    shut

    int s1
    desc connected to Site C T1
    no ip address
    bridge-group 1

    Site C - Router with 192.168.0.2 on serial interface

    If I take the 2 routers with 192.168.0.x back to back with a T1 crossover
    they can talk to each other.

    Will this work ? Should this work ? Any help would be appreciated. We are
    looking to replace the GBIC trunk with an ATM switch, but they won't happen
    in time for this circuit.
    If anyone knows of a fairly cheap media converter that will pass DS1 or DS3
    over an ethernet link I am game as well (under $1000 for both sides)

    Thanks
    Rick
     
    Rick G, Jul 11, 2003
    #1
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  2. Rick G

    Chris O Guest

    Chris O, Jul 11, 2003
    #2
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  3. Rick G

    RC Guest

    Before I get into this remember you said it was backwards.
    First, why do you want the T1 interface? Is it for voice traffic to/from a
    PBX, or is it just some kind of DTE/DCE setup that only offers a T1
    interface?

    If it's the latter you could try BSTUN, and I thought I'd never come across
    it again. To be honest I'm not even sure it is still supported. But it
    "Should" work.

    For the former, a voice T1, I don't think BSTUN would work well, if at all.
    For that you need to use a couple of gateways (1751, 1760, 2600, 3600, and
    up). Do this all the time, works great, but you will need 802.1p and 802.1q
    on the switches. It sounds like you have lots of site-to-site bandwidth so
    go for uncompressed (G.711) and save on DSPs.

    You can contact me off-line, just remove the <no spam>
     
    RC, Jul 11, 2003
    #3
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