vlans and ip addresses

Discussion in 'Cisco' started by tony, Aug 17, 2006.

  1. tony

    tony Guest

    I have a large block of ip addresses 255.255.248.0 on a lan. I am going to
    have one so called core switch (4506) and some 4503 on different floors home
    run to this core 4506 switch. currently DNS, DHCP are outside of this
    network. The 4506 core switch has 2 WS-X4306 (6 port GBIC modules). I want
    each GBIC to be on its own vlan.

    Question is what ip address am i suppose to assign the vlans? All hosts get
    random DHCP addresses already assigned and I am not able to separate all the
    hosts per floor to a different vlan. I can only assign each floor (a 4503)
    to a different vlan.

    Does this make sense?
     
    tony, Aug 17, 2006
    #1
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  2. In article <ec2r34$mko$>, "tony" <>
    wrote:

    > I have a large block of ip addresses 255.255.248.0 on a lan. I am going to
    > have one so called core switch (4506) and some 4503 on different floors home
    > run to this core 4506 switch. currently DNS, DHCP are outside of this
    > network. The 4506 core switch has 2 WS-X4306 (6 port GBIC modules). I want
    > each GBIC to be on its own vlan.
    >
    > Question is what ip address am i suppose to assign the vlans? All hosts get
    > random DHCP addresses already assigned and I am not able to separate all the
    > hosts per floor to a different vlan. I can only assign each floor (a 4503)
    > to a different vlan.
    >
    > Does this make sense?


    A VLAN should be treated like a real LAN. Each VLAN needs to be a
    different IP subnet.

    --
    Barry Margolin,
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***
     
    Barry Margolin, Aug 18, 2006
    #2
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  3. tony

    tony Guest

    I am not sure i can change everyone's ip address.

    Baisically we are assigned a subnet say 10.10.184.1- 10.10.190.255 /21
    subnet. Gateway 10.10.184.1

    The DHCP is outside of this network. Everyone within my net on all floors
    gets random ip addresses, 5th floor user might get 10.10.187.5, and another
    user on 5th floor might get 10.10.184.10. Do I have to get all the hosts on
    each floor and have them grouped together into a closer subnet like say

    5th floor - 10.10.184.10-10.10.184.255
    4th floor - 10.10.185-10-10.10.185.255

    etc etc....

    What about dynamic vlans?

    "Barry Margolin" <> wrote in message
    news:...
    > In article <ec2r34$mko$>, "tony" <>
    > wrote:
    >
    >> I have a large block of ip addresses 255.255.248.0 on a lan. I am going
    >> to
    >> have one so called core switch (4506) and some 4503 on different floors
    >> home
    >> run to this core 4506 switch. currently DNS, DHCP are outside of this
    >> network. The 4506 core switch has 2 WS-X4306 (6 port GBIC modules). I
    >> want
    >> each GBIC to be on its own vlan.
    >>
    >> Question is what ip address am i suppose to assign the vlans? All hosts
    >> get
    >> random DHCP addresses already assigned and I am not able to separate all
    >> the
    >> hosts per floor to a different vlan. I can only assign each floor (a
    >> 4503)
    >> to a different vlan.
    >>
    >> Does this make sense?

    >
    > A VLAN should be treated like a real LAN. Each VLAN needs to be a
    > different IP subnet.
    >
    > --
    > Barry Margolin,
    > Arlington, MA
    > *** PLEASE post questions in newsgroups, not directly to me ***
    > *** PLEASE don't copy me on replies, I'll read them in the group ***
     
    tony, Aug 18, 2006
    #3
  4. tony

    Phil Schuman Guest

    I've been scratching my head while reading various threads on vlans.
    In a nutshell, should you think of vlans just like a physical lan &
    subnets.
    Where and how do you place a DHCP server in a vlan environment
    or any other application server shared by the various vlans...
    Do you windup with a single arm router concept with the vlans
    talking to the required servers via a local router
    which in effect will increase the utilization of the router
    along with consuming more bandwidth for back & forth to the router.
     
    Phil Schuman, Aug 18, 2006
    #4
  5. In article <ec4pd8$isk$>, "tony" <>
    wrote:

    > I am not sure i can change everyone's ip address.
    >
    > Baisically we are assigned a subnet say 10.10.184.1- 10.10.190.255 /21
    > subnet. Gateway 10.10.184.1
    >
    > The DHCP is outside of this network. Everyone within my net on all floors
    > gets random ip addresses, 5th floor user might get 10.10.187.5, and another
    > user on 5th floor might get 10.10.184.10. Do I have to get all the hosts on


    Then you need to make a flat network connecting all the floors.

    > each floor and have them grouped together into a closer subnet like say
    >
    > 5th floor - 10.10.184.10-10.10.184.255
    > 4th floor - 10.10.185-10-10.10.185.255
    >
    > etc etc....


    Yes.

    >
    > What about dynamic vlans?


    I'm not familiar with them.

    Like I said before, a VLAN acts just like a normal LAN. VLANs are a way
    to split up the segments connected to a switch, or a collection of
    switches, into separate broadcast domains. IP over Ethernet expects all
    the hosts in a subnet to be in the same broadcast domain.

    There are some tricks you can play with proxy ARP that allow you to
    handle a few exceptions to this rule, but it's not really workable if
    everything is random, like you say.

    If you use DHCP, I think you should be able to get rid of the
    randomness. I'm not really familiar with DHCP server configuration, but
    I assume most of them are able to assign addresses within the
    appropriate subnet, based on the information provided by the DHCP relay.

    --
    Barry Margolin,
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***
     
    Barry Margolin, Aug 19, 2006
    #5
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