Switch question: per-port DHCP question

Discussion in 'Networking & Security' started by tshen_83, Mar 14, 2006.

  1. tshen_83

    tshen_83 Limp Gawd

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    Hi,

    I am searching for a solution at a networking problem:

    Like a router, where there is a DHCP server on the router,
    I need a 12, 16 or 24 port switch that is able to assign specific, preconfigured IP address to each individual port.(ie 192.168.0.1 to port 1 via DHCP protocol, 192.168.0.2 to port2, so if I plug a DHCP client device into port 1, it will get 192.168.0.1 as its address, plug the same device to port2 gets 192.168.0.2)

    The switch also needs to be SNMP capable for monitoring, so it's probably going to be a managed switch.

    Anyone know of a solution? please let me know.
     
  2. MorfiusX

    MorfiusX 2[H]4U

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    I don't think you are going to get exactly what you are looking for as I don't think it's possible. The only thing I can think of is to create a VLAN for each port. Then use an IP helper for each VLAN.
     
  3. Asgorath

    Asgorath [H]ard|Gawd

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    What is the application for this. I'm sure there is a better way of doing it. This 'easy' problem sounds like it's going to be an expensive one to impliment.
     
  4. PHUNBALL

    PHUNBALL Gawd

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    Yes, what are you trying to do? I can't think of any use for something like this...

    Are you trying to track devices by port or something of that nature? If so, you can do that without what you are talking about...
     
  5. Zamboni

    Zamboni [H]ard|Gawd

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    We used to have a switch where we could assign IP addresses to the switch ports, but it couldn't assign addresses to anything that was plugged into it.

    (has quick nighmare of a switch with 24 range-1 DHCP routers)
     
  6. Dew

    Dew 2[H]4U

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  7. TrueBuckeye

    TrueBuckeye Most valuable "member"

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    Wow, through DHCP? The vlan solution is clunky, but possible. And I can't think of any other way of doing it.

    If the computers in each switch were static, then you could always do DHCP reservations based on computername/MAC, but then I think that defeats your purpose, right?
     
  8. tshen_83

    tshen_83 Limp Gawd

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    hi, guys. I know this isn't a typical solution to ask for. However, the goal is to assign static IPs to Ethernet Devices without having to individually configure them. We just plug them into specific port on the switch and all the Ethernet Devices will pick up the IP assigned to each port. This is for the use case of not having to manually configure anything and still know what IPs gets assigned to what devices automatically.

    please help.
     
  9. tshen_83

    tshen_83 Limp Gawd

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    i did a freaking ton of research lately, and only few Level 3 Switches support DHCP relay agent Option 82 RFC 3046.

    The ones that does work are: Netgear FSM73xx series, Cisco IOS based Layer 3 Swtiches.

    We will be using ISC DHCPD server, however google turns up very few instructions on how to configure the ISC DHCPD server to use the agent.circuitID provided by the option 82 feature on the Layer 3 Switches mentioned above

    please help!
     
  10. Xipher

    Xipher 2[H]4U

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  11. PHUNBALL

    PHUNBALL Gawd

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    You can do this on your DHCP server. Simply pull the MAC addresses from each device (this can also be done by viewing the ARP cache on the switch where the devices are connected) and create an address reservation on your DHCP server for that IP and that MAC...
     
  12. MorfiusX

    MorfiusX 2[H]4U

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  13. PHUNBALL

    PHUNBALL Gawd

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    The problem is, he is trying to do this with a switch (possibly layer 3) and assign a single IP address from the same scope on each port of the switch...
     
  14. moetop

    moetop [H]ard|Gawd

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    From his original statement "(ie 192.168.0.1 to port 1 via DHCP protocol, 192.168.0.2 to port2, so if I plug a DHCP client device into port 1, it will get 192.168.0.1 as its address, plug the same device to port2 gets 192.168.0.2)" Doing a simple manual DHCP assignment wont get what he wants done. He wants it by port, so if the same MAC address travels from one port to another it will get a diffrent IP address.

    This is a realy odd request. Can we get more details to the reason you want to do this?
     
  15. tshen_83

    tshen_83 Limp Gawd

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    the reason is for manufacturing. If we get a bunch of Ethernet based control system devices(i can't go into details much more) they are all the same. We can purchase 20 of them and put it on the network. We don't want to write static IPs to each of them manually as that will take time and can't be automated. Writing MAC addresses into the DHCP server also takes time. What we want is to plug a device into one port and know that the device will get a specific IP. That way, replacing a device is also just unplug then plug another one in. All devices will be DHCP clients enabled
     
  16. Asgorath

    Asgorath [H]ard|Gawd

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    That would work if he always plugged the same device into that port, but he wants to be able to plug ANYTHING into that port and have it resolve to the same IP. ---> The mac address changes!

    That is the reason this is a crazy problem.
     
  17. Malk-a-mite

    Malk-a-mite [H]ard|Gawd

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    Do you have any idea the time you are looking at to setup the system you are asking about?

    VLANs with single IP scope per VLAN seems to be the best option for the situtation you have proposed. Unless something changes I'm not sure what else can be suggested.
     
  18. tshen_83

    tshen_83 Limp Gawd

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    I already read into the IP Helper command. It's not exactly what we want to do. Plus that will lock us into Cisco only switches.(If Layer3 Manged switch with Option 82 RFC3046 wasn't hard enough to find for cheap already)

    Please guys...someone out there in the industrial world probably thought about this already....

    For example MOXA EDS series of redundant switches support that feature...but they are too expensive.
     
  19. tshen_83

    tshen_83 Limp Gawd

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    I will look into that. Still is there anything out there that will give me instructions on how to configure the ISC DHCPD using the Option-82(RFC3046)'s agent.circuitID to assign each port? It looks possible, but not even ISC DHCP's own website has too much info on it.

    Thanks
     
  20. tshen_83

    tshen_83 Limp Gawd

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    what's the performance penalty of having each port as its VLAN(latency, bandwidth throughput)
     
  21. PHUNBALL

    PHUNBALL Gawd

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    I understnad that as per my previous comments, I'm just trying to give him a solution to a problem that does not have one...
     
  22. PHUNBALL

    PHUNBALL Gawd

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    Your problem would be that now you must route all of your traffic instead of simply switching the traffic. Routing obviously consumes more resources and is slower than switching. Are you saying that these devices get swapped out so often (daily??) that it is not possible to keep up with them???

    Basically, if this is a production environment, you would not want to do it that way...
     
  23. tshen_83

    tshen_83 Limp Gawd

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    Does anyone here know how to configure the ISC DHCPd server to support Option 82? Even ISC's own forum doesn't have much information on it.

    Thanks