ITEM: Q4308L

bootp server, secondary bootp server setup


Item: Q598820        Dated: September  92

I am trying to configure Risc System/6000's as both primary and
secondary bootp servers.  We have successfully defined the bootptab
entry as a primary server.  We are booting both IBM x-stations and
a lot of 3rd party hardware (bridges, etc.).  We are having difficulty
defining the entry as a secondary server.  We would like to be able
to set a timeout value on the secondary server so that it will not
boot the device unless the primary server is down.  We cannot make
the timeout value work correctly.  Can you give us a working example
of a bootptab entry with a timeout?  Thank you.

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A: The T175 tag is the field your looking for in the bootptab entry.
   for example (/etc/bootptab):


   Note that this is the type of entry that would be created if you
   were to define an Xstation's server as a secondary boot host.

   By adding the T175=60 parameter, you are specifying that this
   server is secondary, and it will wait 60 seconds in responding
   to the bootp request.

   Background information:

   There is a field in the bootp REQUEST packet sent by the bootp
   client (i.e. Xstation or whatever) which indicates the elapsed time
   (seconds) since the client first attempted to boot.  This field is
   part of the bootp protocol, so that any client should fill in the
   field.  When a bootp request is received by the server (bootpd), the
   bootpd will locate the requesters entry in /etc/bootptab.  If an
   entry is found, and the T175 tag exists, the elapsed time specified in
   the bootp request packet is compared with the value associated with
   the T175 tag.  If the value in the request packet is greater than the
   T175 tag value, then bootp returns the appropriate values to the
   client, otherwise it does not.

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Item: Q595701        Dated: August  92

I'm am in need of "how-to" information on setting up a Risc/6000
bootp server for PCs running IBM's TCP/IP for DOS V2, and do not
find such step-by-step procedures in the AIX V3 commands reference
or communications books.  A customer wants to set up such an
environment over their Ethernet LAN in which the bootp request
gets in response its IP address.

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A: First, the function of bootp is, given the hardware address of a
   client machine, provide a server address and possibly a pathname of
   a bootfile to download using TFTP.  This is the function that
   both our IBM Xstations and the 220 Diskless/Dataless environments
   use and that is probably the best source of information. i.e.
   The Xstation System Management Guide, and the IBM Diskless
   Workstation Management Guide.

   I will outline the steps in setting up a bootp entry in
   the /etc/bootptab file which is where the resolution takes place.

     if your running AIX 3.1 you need Xstation Manager - Bootp is part
     of the x_st_mgr.obj software in 3.1.  If your running AIX 3.2 it
     is part of the BOS - so you DON'T need x_st_mgr installed to have
     bootp functionality.

     /etc/services - verify the following entries exist:
         bootps       67/udp
         bootpc       68/udp
         tftp         69/udp

    /etc/inetd.conf - verify the following entries exist and uncommented:
      tftp   dgram   udp    wait   nobody   /etc/tftpd     tftpd -n
      bootps drgam   udp    wait   root     /etc/bootpd    bootpd

    The tftp entries are not really important if your not downloading
    a boot image - but I provide them to you as examples of what the
    Xstation and IBM Diskless environment use for consistency.

    Issue these command to make the above changes take effect:
       refresh -s inetd

   Next you will "construct" a bootptab entry in /etc/bootptab:
     Assumptions for example:
       PC hardware address of   08005a123456
       IP address of PC
       hardware type is         token ring
       hostname is              pc1

   /etc/bootptab entry would be:


    Functionally what happens?  The PC broadcasts it's hardware address
    to the LAN - inetd picks up the request and sees that it's a bootp
    request and starts bootpd.  Bootpd looks in it's /etc/bootptab file
    for a hardware address match, and send back the appropriate IP
    address which corresponds if found.

$IBM    One additional source of information (in addition
$IBM    to the x_st_mgr documentation and diskless documentation) is
$IBM    the BOOTP RFC.  To obtain:

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Support Line: bootp server, secondary bootp server setup ITEM: Q4308L
Dated: January 1995 Category: N/A
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