Need advice on best way to cut over to new network

Discussion in 'Cisco' started by Ned, Mar 26, 2007.

  1. Ned

    Ned Guest

    I have an existing network, and a new network that I installed in
    parallel using spare fiber. The core is being completely replaced, and
    each of our 13 closets has had a single 48 port gigabit switch added
    to it. These Gig switches are connected and online with the new core
    on seperate fiber. My goal is to do as much as I can before the
    weekend when we cut over. Ideally, there would be minimal running
    around and some config changes at the console. I am thinking of
    connecting the existing 10/100 switches in our mdf's to the new Gig
    switches using crossover cables. Since I have configured the new core
    to use the same gateways and IP addresses as the existing core I am a
    little nervous about causing problems. I was thinking of disabling the
    ports with the crossover cables and enabling them on the cutover date.
    I think there might be an easier way, maybe limiting traffic over the
    trunks to management vlan packets only, until the cutover date, then
    turning off the old core switch and activating all the vlans on the
    new core. I would appreciate your recommendations since this is my
    first time doing this and I am just learning about Cisco switches.
    Thanks!
    NH
    Ned, Mar 26, 2007
    #1
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  2. Ned

    Trendkill Guest

    On Mar 26, 6:40 pm, "Ned" <> wrote:
    > I have an existing network, and a new network that I installed in
    > parallel using spare fiber. The core is being completely replaced, and
    > each of our 13 closets has had a single 48 port gigabit switch added
    > to it. These Gig switches are connected and online with the new core
    > on seperate fiber. My goal is to do as much as I can before the
    > weekend when we cut over. Ideally, there would be minimal running
    > around and some config changes at the console. I am thinking of
    > connecting the existing 10/100 switches in our mdf's to the new Gig
    > switches using crossover cables. Since I have configured the new core
    > to use the same gateways and IP addresses as the existing core I am a
    > little nervous about causing problems. I was thinking of disabling the
    > ports with the crossover cables and enabling them on the cutover date.
    > I think there might be an easier way, maybe limiting traffic over the
    > trunks to management vlan packets only, until the cutover date, then
    > turning off the old core switch and activating all the vlans on the
    > new core. I would appreciate your recommendations since this is my
    > first time doing this and I am just learning about Cisco switches.
    > Thanks!
    > NH


    I agree with your suggestion. If you want to eliminate physical work
    on cutover, run the cables and plug them in, but disable them on your
    core only. On night of cutover, shutdown the old core's interface,
    and bring up the new core's interface. That way if you need to back
    out, you can just reverse without worrying about losing connectivity
    to the IDF switches (at least in theory). Do not, and I repeat do
    not, turn up the new core with same vlans and ip addresses prior to
    cutover or you will have problems. Well unless of course your new
    core is connected to your old core and has all of your LAN/WAN routing
    connections. (IE, your old core is .2 and .3, and your new core is .4
    and .5 with all the same HSRP group, etc). I'd just avoid that to be
    safe if you can avoid it.......
    Trendkill, Mar 27, 2007
    #2
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  3. Ned

    Ned Guest

    On Mar 27, 8:27 am, "Trendkill" <> wrote:
    > On Mar 26, 6:40 pm, "Ned" <> wrote:
    >
    >
    >
    >
    >
    > > I have an existing network, and a new network that I installed in
    > > parallel using spare fiber. The core is being completely replaced, and
    > > each of our 13 closets has had a single 48 port gigabit switch added
    > > to it. These Gig switches are connected and online with the new core
    > > on seperate fiber. My goal is to do as much as I can before the
    > > weekend when we cut over. Ideally, there would be minimal running
    > > around and some config changes at the console. I am thinking of
    > > connecting the existing 10/100 switches in our mdf's to the new Gig
    > > switches using crossover cables. Since I have configured the new core
    > > to use the same gateways and IP addresses as the existing core I am a
    > > little nervous about causing problems. I was thinking of disabling the
    > > ports with the crossover cables and enabling them on the cutover date.
    > > I think there might be an easier way, maybe limiting traffic over the
    > > trunks to management vlan packets only, until the cutover date, then
    > > turning off the old core switch and activating all the vlans on the
    > > new core. I would appreciate your recommendations since this is my
    > > first time doing this and I am just learning about Cisco switches.
    > > Thanks!
    > > NH

    >
    > I agree with your suggestion. If you want to eliminate physical work
    > on cutover, run the cables and plug them in, but disable them on your
    > core only. On night of cutover, shutdown the old core's interface,
    > and bring up the new core's interface. That way if you need to back
    > out, you can just reverse without worrying about losing connectivity
    > to the IDF switches (at least in theory). Do not, and I repeat do
    > not, turn up the new core with same vlans and ip addresses prior to
    > cutover or you will have problems. Well unless of course your new
    > core is connected to your old core and has all of your LAN/WAN routing
    > connections. (IE, your old core is .2 and .3, and your new core is .4
    > and .5 with all the same HSRP group, etc). I'd just avoid that to be
    > safe if you can avoid it.......- Hide quoted text -
    >
    > - Show quoted text -


    Thanks for responding. I have 13 IDFs with 3 crossover cables in each,
    that's 39 ports to disable/enable.
    Is there an easier way to limit the traffic? I used an allowed vlans
    command at the core, could I just disable those vlans (except for
    management) and stope the traffic that way? Any ideas?
    thanks
    Ned, Mar 27, 2007
    #3
  4. Ned

    Trendkill Guest

    On Mar 27, 12:36 pm, "Ned" <> wrote:
    > On Mar 27, 8:27 am, "Trendkill" <> wrote:
    >
    >
    >
    > > On Mar 26, 6:40 pm, "Ned" <> wrote:

    >
    > > > I have an existing network, and a new network that I installed in
    > > > parallel using spare fiber. The core is being completely replaced, and
    > > > each of our 13 closets has had a single 48 port gigabit switch added
    > > > to it. These Gig switches are connected and online with the new core
    > > > on seperate fiber. My goal is to do as much as I can before the
    > > > weekend when we cut over. Ideally, there would be minimal running
    > > > around and some config changes at the console. I am thinking of
    > > > connecting the existing 10/100 switches in our mdf's to the new Gig
    > > > switches using crossover cables. Since I have configured the new core
    > > > to use the same gateways and IP addresses as the existing core I am a
    > > > little nervous about causing problems. I was thinking of disabling the
    > > > ports with the crossover cables and enabling them on the cutover date.
    > > > I think there might be an easier way, maybe limiting traffic over the
    > > > trunks to management vlan packets only, until the cutover date, then
    > > > turning off the old core switch and activating all the vlans on the
    > > > new core. I would appreciate your recommendations since this is my
    > > > first time doing this and I am just learning about Cisco switches.
    > > > Thanks!
    > > > NH

    >
    > > I agree with your suggestion. If you want to eliminate physical work
    > > on cutover, run the cables and plug them in, but disable them on your
    > > core only. On night of cutover, shutdown the old core's interface,
    > > and bring up the new core's interface. That way if you need to back
    > > out, you can just reverse without worrying about losing connectivity
    > > to the IDF switches (at least in theory). Do not, and I repeat do
    > > not, turn up the new core with same vlans and ip addresses prior to
    > > cutover or you will have problems. Well unless of course your new
    > > core is connected to your old core and has all of your LAN/WAN routing
    > > connections. (IE, your old core is .2 and .3, and your new core is .4
    > > and .5 with all the same HSRP group, etc). I'd just avoid that to be
    > > safe if you can avoid it.......- Hide quoted text -

    >
    > > - Show quoted text -

    >
    > Thanks for responding. I have 13 IDFs with 3 crossover cables in each,
    > that's 39 ports to disable/enable.
    > Is there an easier way to limit the traffic? I used an allowed vlans
    > command at the core, could I just disable those vlans (except for
    > management) and stope the traffic that way? Any ideas?
    > thanks


    After re-reading your first post, I think I have a little bit better
    of an idea of what you are doing. So if i understand correctly, you
    have a completely new layer2/3 core, and new IDF switches that sit
    next to your old IDF switches, that currently run back to an old
    core. I would consider turning up the trunks between your new and old
    IDF switches, and keep the ports blocked at your new core. On night
    of cutover, I would disable your old core's trunks to the old
    switches, and enable the new core's trunks. You would technically be
    moving from old core -> old idf -> new idf X -> new core to a
    configuration that is new core -> new idf -> old idf X -> old core.
    Providing your configs are exactly the same, this should work
    presuming your trunks are all identical on all these trunks (existing
    and new).

    Personally if you can prune back VLANs that don't need to go to an
    IDF, you should do so, but it is not a prerequisite and you can always
    go back and prune later. However, I would strongly encourage you to
    completely shut down the old core on cutover, and if you are going to
    use both the old and new idf switches long term, each of those should
    be homed to the core, not daisy chained off one another. In short,
    and in my production world we use 4 gig etherchannel, but one fiber
    gig link from core 1 to idf 1a and idf 1b each, and one gig fiber link
    from core 2 to idf 1a and idf 1b. I would not only prune back VLANs
    you dont need, but I would make Core 1 own layer2/3 (vlan/hsrp
    priority) for odd vlans and Core 2 own layer2/3 for even vlans. As I
    said above, these can be changes for another day, but I would caution
    you against keeping a 'square' architecture.
    Trendkill, Mar 27, 2007
    #4
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