WDM Enterprise Imaging Accross WAN – Need Some Help

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  • #1147
    mlgary
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    I am new to this forum and relativly new to thin clients so I appreciate any help I can get. Now I know first thing off is that imaging accross the WAN is not a good idea but I need some direction anyways. Our company will do images accroos the WAN as an option of last resort. Here is my delima. Our DHCP is handled locally on the router. All of my branch sites are on class C network. We are bridging from one class C to another class C network. Using the IP helper on our interface the server sees the 941G terminal as PXE capable accross the wan. We start the reboot and the terminal then fails to get an IP address from the local router during PXE. When the router , server, and terminal are on the same subnet using the came DHCP router code it works fine. Something is getting lost in the transition from WAN to WAN. I would think the local terminal should still pick up an IP address but it does not. The image process tries and retries unitl it times out. Here is a snip of our router code on the side of the lan that the terminal is on. The other side is our corporate network.
    We are using Cisco 2801 routers and 2950 switches. Any ideas appreciated.

    ip dhcp pool wyse_pool
    network 10.10.2.0 255.255.255.0
    bootfile Xpe_Full
    default-router 10.10.2.1
    option 186 ip 10.10.5.6 (


    WDM server
    option 187 ascii “4011”

    interface FastEthernet0
    ip address 10.10.2.1 255.255.255.0
    ip helper-address 10.10.5.6 (—- WDM server
    speed auto

    #12769
    ConfGen
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    Have you done a network trace to see if the DHCP server is handing out an IP address?
    Do you get an error message on the client after PXE?

    CG

    #12771
    mlgary
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    • Regular Joe
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    I can see from my wireshark in the bootstrap portion that the pxe device ( mac address ) is picking up the first address in the pool. But from there that address never gets forwarded over to the WDM server even though I have the IP helper addresses in place. The PXE…. process keeps going until I get a no Bootfile message. I get a DHCP discover and offer for each of the …. Has anyone ran WDM imaging accross a wan using the router on the client side as the dhcp server? I have tried placing the helper on the ethernet and the serial interface to no avail. If the server is placed on the same subnet all is well. I know something isnt getting routed but I cannot figure out what.

    #12772
    thinkthin
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    Great question but this will require a long answer – I will post back shortly…

    #12777
    thinkthin
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    Hi,

    The issue is here to do with the way the PXE RFC is constructed. Primarily that the PXE service and DHCP both listen for the UDP DHCP REQ packet and this is on port 66.

    So when you run DHCP on the router the router responds to the packet and does not forward it on. The same would happen if you ran DHCP and PXE on the same Windows box. So what to do?

    Well, if these are the only PXE boxes on the network you can hard-code the PXE response into a DHCP option tag on the Cisco router and remove the IP Helper (it has no effect anyway)

    Now as I am on the road at the moment I will need to look up some notes on the correct format and which tag it is. I remember its a binary value and I can say that it works like a dream but any device that is PXE booted will try to contact the WDM server.

    Sorry this answer is 3 parts over 2 days, I have been meaning to write up a tech doc on this solution for a while!

    Cheers,
    -TT

    #12784
    Harry20
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    • Regular Joe
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    I’ve hit this too. My network guy implemented the hex and now it sees PXE a treat….bar it’s too slow to work!

    If you can’t find the Hex let me know and I’ll post it or PM it to u.

    #12789
    mlgary
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    • Regular Joe
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    Thanks I would appreciate the write up the tags I get from the documentation are (to me) represented like this..

    option 186 ip 10.10.5.6 (


    WDM server
    option 187 ascii “4011” (


    Communitcation Port

    Please help me rewrite these tags and I’ll kill the IP helper.

    I run a mixed HP thin client and wyse network but no store has both installed. I keep the 2 manufaturers split so there is no chance of routing problems. The HP’s will be managed by Altiris.

    Some stores will be Altiris managed (20%) some will be WDM (80%)

    #12803
    thinkthin
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    Hi,

    Ok, in a nut shell we need to user the following in you DHCP Pool:

    option 60 ascii “PXEClient”
    option 43 hex 0601.0708.0700.0e01.0a10.02ab.0905.000e.0252.420a.0200.52ff

    Now the important part is the breakdown of the code the first Hex digit is the sub option code, the next one is the length of the data and the next n are the data, so this: 06 01 07 08 07 00 0e 01 [0a 64 0f 74] 09 05 00 0e 02 52 42 0a 02 00 52 ff

    Now see the square brackets, we need to get out the calculator and convert the ip address to hex.

    I hope this makes sense,

    Cheers,
    -TT

    #12817
    mlgary
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    • Regular Joe
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    Thank You very much that did the trick.. My project is back on schedule. WDM will be in production in 2 weeks.. I have 1200 Thin Clients to manage.

    Once again your a life saver.

    Michael Gary
    Branch Services Supervisor
    Goodman Manufacturing Co LP

    #12855
    Harry20
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    • Regular Joe
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    Great to here someone else has had success with this, I had it outstanding for ages until I got a solution.

    Now all I need is mega bandwidth!

    #12858
    thinkthin
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    Or WDM enterprise, you can run FTP on one of the terminals with the image in the remote subnet and and use it as the image source. This actually works well!

    Cheers,
    -TT

    #12902
    mlgary
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    • Regular Joe
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    thats along the lines of my plan. PXE boot 1 image to my store accross our slow WAN. Then use the local FTP to fix the other devices on the local subnet.

    #12903
    mlgary
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    • Total Post: 27
    • Regular Joe
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    option 60 ascii “PXEClient”
    option 43 hex 0601.0708.0700.0e01.0a10.02ab.0905.000e.0252.420a.0200.52ff

    Is any of this Hex string vendor specific to WDM?

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