Switch or Router for routing betwean VLANS with 500 computers

Discussion in 'Cisco' started by Morph, Apr 7, 2008.

  1. Morph

    Morph Guest

    Hi.
    We have a situation where we have around 500 computers and servers that
    will be separated in to several (5-6) VLANS (currently they are all in
    the same network.
    The servers will be in a separate VLAN and a lot of traffic will go
    there. There won't be much traffic betwean the other VLANs.

    What would you sugest as a device that would route betwean the VLANS?
    The users are connected through Linksys Gigabit swithches, and I thought
    about using a Layer 3 switch to do the inter VLAN routing.
    In perticular I thought about using WS-C3750G-24TS-1U with an IP Base
    image (IP base supports static routes and RIP).

    Will this be a good solution? Is a C3750 enough for this or do I need a
    C3750E?
     
    Morph, Apr 7, 2008
    #1
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  2. Morph

    Trendkill Guest

    While it completely depends on traffic between vlans and/or across
    trunks from a pure utilization perspective, either switch will have
    enough routing capability to handle this. You are talking a half
    dozen routed interfaces at most, and 500 nodes, should be completely
    fine. We'll see what the others think, but I would not see any
    problem with this setup.
     
    Trendkill, Apr 7, 2008
    #2
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  3. Morph

    Morph Guest

    In the message
    <>
    Trendkill wrote:

    | > Hi.
    | > We have a situation where we have around 500 computers and servers that
    | > will be separated in to several (5-6) VLANS (currently they are all in
    | > the same network.
    | > The servers will be in a separate VLAN and a lot of traffic will go
    | > there. There won't be much traffic betwean the other VLANs.
    | >
    | > What would you sugest as a device that would route betwean the VLANS?
    | > The users are connected through Linksys Gigabit swithches, and I thought
    | > about using a Layer 3 switch to do the inter VLAN routing.
    | > In perticular I thought about using WS-C3750G-24TS-1U with an IP Base
    | > image (IP base supports static routes and RIP).
    | >
    | > Will this be a good solution? Is a C3750 enough for this or do I need a
    | > C3750E?
    |
    | While it completely depends on traffic between vlans and/or across
    | trunks from a pure utilization perspective, either switch will have
    | enough routing capability to handle this. You are talking a half
    | dozen routed interfaces at most, and 500 nodes, should be completely
    | fine. We'll see what the others think, but I would not see any
    | problem with this setup.

    Hi Trendkill. Thanx for your reply.

    The nodes are connected to 7 - 48 port Linksys gigabit switches, and 4
    24 port switches (for the moment) so there will be 11 or 12 routed
    interfaces on the C3750.
     
    Morph, Apr 7, 2008
    #3
  4. Morph

    Merv Guest

    With 500 users you may want to give consideration to having two layer
    3 switches for redundancy.

    The layer 2 access switches would be dual-homed to the layer 3
    switches
     
    Merv, Apr 8, 2008
    #4
  5. Morph

    Morph Guest

    In the message
    <> Merv
    wrote:

    | With 500 users you may want to give consideration to having two layer
    | 3 switches for redundancy.
    |
    | The layer 2 access switches would be dual-homed to the layer 3
    | switches

    Hi Merv.
    If I understood correct you are sugesting to have the Layer 2 switches
    connected through trunks to both of the Layer 3 (3750) switches.
    Is some aditional configuration needed other than setting up trunks and
    routing on the 3750s?
    Thank you.
     
    Morph, Apr 8, 2008
    #5
  6. Morph

    Trendkill Guest

    Setup the vlans on both 3750s, with HSRP, and trunk all vlans between
    them. Then connect each of your access switches to the 3750s, using
    trunking if you need multiple vlans on an access switch. This will
    give you full layer 2 and layer 3 redundancy, at least on the lan. Of
    course you still may not have redundancy down the server/workstation
    port (this would require pairs of access switches), but its a step in
    the right direction.
     
    Trendkill, Apr 8, 2008
    #6
  7. Morph

    Merv Guest

    Trendkill has spoken to your question.

    You could also put your servers on access switches that are dual-homed
    to new layer 3 switches
     
    Merv, Apr 8, 2008
    #7
  8. Morph

    Morph Guest

    In the message
    <>
    Trendkill wrote:

    | > | With 500 users you may want to give consideration to having two layer
    | > | 3 switches for redundancy.
    | > |
    | > | The layer 2 access switches would be dual-homed to the layer 3
    | > | switches
    | >
    | > Hi Merv.
    | > If I understood correct you are sugesting to have the Layer 2 switches
    | > connected through trunks to both of the Layer 3 (3750) switches.
    | > Is some aditional configuration needed other than setting up trunks and
    | > routing on the 3750s?
    | > Thank you.
    |
    | Setup the vlans on both 3750s, with HSRP, and trunk all vlans between
    | them. Then connect each of your access switches to the 3750s, using
    | trunking if you need multiple vlans on an access switch. This will
    | give you full layer 2 and layer 3 redundancy, at least on the lan. Of
    | course you still may not have redundancy down the server/workstation
    | port (this would require pairs of access switches), but its a step in
    | the right direction.

    If buying two 3750s I would like to not only have one that is active,
    and one that is standing by, but to load balance traffic across the two
    switches using MHSRP. Hopefully this is possible with the IP base IOS.
    Software advisor mentions HSRP as a feature and doesn't mention MHSRP.

    Another problem I'm gonna face is that the addresses will be handed out
    from one DHCP server for all the 500 machines. This should not be a
    problem when implementing HSRP, but for MHSRP half the nodes in every
    VLAN should receive different default gateways. Any idea how to overcome
    this?
    Thank you.
     
    Morph, Apr 8, 2008
    #8
  9. Morph

    Trendkill Guest

    If you want to load share, I would just do hsrp and use the hsrp
    priorities to load balance odd vlans on one switch and the evens on
    the other. No reason to load balance within a vlan that I can see
    given the small nature of your network. Then you just have ip-helpers
    on both switches.

    Second, even with different gateways, gateways have nothing to do with
    dhcp, so it shouldnt be a problem. The router will forward the bootp
    packets to the dhcp server based on the ip-helper, and then use a
    source of its own interface which tells the dhcp server where to reply
    and what network the dhcp request is coming from. I don't think this
    is an issue regardless of which direction you go, hsrp or mhsrp. I
    would go with the former though, no need to over-complicate things.
    Not to mention I suspect you dont have fully redundant/load balanced
    next hops, so the only thing you are distributing is lan traffic,
    which is still limited by your uplinks/trunk ports/server connections.
     
    Trendkill, Apr 8, 2008
    #9
  10. Morph

    Merv Guest


    Before you do this figure out if the uplinks will be a bottleneck.

    The extra complexity may not be worthwhile.

    also if you have the budget you could replace your layer 2 access
    switches at the same time
    with layer 3 access switch then you would not have the headaches that
    STP can bring and
    you would not require HSRP ...
     
    Merv, Apr 8, 2008
    #10
  11. Morph

    Morph Guest

    | Hi.
    | We have a situation where we have around 500 computers and servers that
    | will be separated in to several (5-6) VLANS (currently they are all in
    | the same network.
    | The servers will be in a separate VLAN and a lot of traffic will go
    | there. There won't be much traffic betwean the other VLANs.
    |
    | What would you sugest as a device that would route betwean the VLANS?
    | The users are connected through Linksys Gigabit swithches, and I thought
    | about using a Layer 3 switch to do the inter VLAN routing.
    | In perticular I thought about using WS-C3750G-24TS-1U with an IP Base
    | image (IP base supports static routes and RIP).
    |
    | Will this be a good solution? Is a C3750 enough for this or do I need a
    | C3750E?

    Thanx Thrill5, Trendkill and Merv for taking the time to reply.
    Your help is greatly appritiated.
    Regards.
     
    Morph, Apr 8, 2008
    #11
  12. Morph

    stephen Guest

    a design guide that may help you
    http://www.cisco.com/application/pdf/en/us/guest/netsol/ns431/c649/ccmigration_09186a008093b876.pdf

    you dont need the full 3 layer design for "only" 500 users.

    what you are discussing follows the cisco guidelines but misses out either
    the core or distribution layer.

    this comes from some cisco general design guides - index:
    www.cisco.com/go/srnd
     
    stephen, Apr 8, 2008
    #12
  13. Morph

    Merv Guest


    a good idea to know all of the design options aavailable nd then make
    a rationale decision based on business needs, budget, etc, etc
     
    Merv, Apr 8, 2008
    #13
  14. Morph

    Morph Guest

    In the message <> Thrill5
    wrote:

    Well this seems like the best solution and at the same time the easyest
    to implement :) Thank you!

    | If you opt for two 3750's, stack them together and they look like one
    | switch, without the need to configure HSRP (or MSHRP) and they will both
    | share the load of routing traffic. Make a layer 2 connection from each of
    | the 3750's to each of the access switches. If one switch fails, the other
    | will detect this in about a half second. Also make sure the 3750 stack is
    | the bridge root, and spanning-tree will failover very quickly as well.
    | Logically this configuration is the same as using dual 6500's with VSS
    | supervisors.
    |
    | | > In the message
    | > <>
    | > Trendkill wrote:
    | >
    | > | > | With 500 users you may want to give consideration to having two
    | > layer
    | > | > | 3 switches for redundancy.
    | > | > |
    | > | > | The layer 2 access switches would be dual-homed to the layer 3
    | > | > | switches
    | > | >
    | > | > Hi Merv.
    | > | > If I understood correct you are sugesting to have the Layer 2 switches
    | > | > connected through trunks to both of the Layer 3 (3750) switches.
    | > | > Is some aditional configuration needed other than setting up trunks
    | > and
    | > | > routing on the 3750s?
    | > | > Thank you.
    | > |
    | > | Setup the vlans on both 3750s, with HSRP, and trunk all vlans between
    | > | them. Then connect each of your access switches to the 3750s, using
    | > | trunking if you need multiple vlans on an access switch. This will
    | > | give you full layer 2 and layer 3 redundancy, at least on the lan. Of
    | > | course you still may not have redundancy down the server/workstation
    | > | port (this would require pairs of access switches), but its a step in
    | > | the right direction.
    | >
    | > If buying two 3750s I would like to not only have one that is active,
    | > and one that is standing by, but to load balance traffic across the two
    | > switches using MHSRP. Hopefully this is possible with the IP base IOS.
    | > Software advisor mentions HSRP as a feature and doesn't mention MHSRP.
    | >
    | > Another problem I'm gonna face is that the addresses will be handed out
    | > from one DHCP server for all the 500 machines. This should not be a
    | > problem when implementing HSRP, but for MHSRP half the nodes in every
    | > VLAN should receive different default gateways. Any idea how to overcome
    | > this?
    | > Thank you.
    |
     
    Morph, Apr 9, 2008
    #14
  15. Morph

    Merv Guest

    The idea behind redundant layer 3 switches is that one is totlally
    independent of the other.

    What happens when you need to upgrade the IOS - you will want to do
    this one at at time - in case there are issue - so that you can easily
    roll back

    Think very carefully about this - it is important.
     
    Merv, Apr 9, 2008
    #15
  16. Morph

    Merv Guest

    one does not have to search very far thru this new sgroup to find
    folks that have had all sort of issues with stacks
     
    Merv, Apr 11, 2008
    #16
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