Switching

I am trying to get a PC to boot from a Novell Zen server on another subnet, getting its initial DHCP parameters from a DHCP pool on the local EX4200. This works OK for geenric Linux and pxelinux but the Novell Zen stuff requires several oddball DHCP options to be set on the DCP server.

 

I have a DHCP pool set up but I can't add "option 60" to it. I want the DHCP server on the EX4200 to return the string "PXEClient" when the PC typing to boot requests Option 60. I assume this is done thusly:

 

{master:0}[edit system services dhcp option 60]
wms2@ccf4200stack# set string PXEClient

{master:0}[edit system services dhcp option 60]
wms2@ccf4200stack# commit
[edit system services dhcp option]
  '60'
    Option can only be set by clients
error: configuration check-out failed

 

This fails too:

 

wms2@ccf4200stack# commit
[edit system services dhcp pool 10.3.1.0/24 option]
  '60'
    Option can only be set by clients
error: configuration check-out failed
 

 

You can see it's failing commit check, and I have no clue what "Option can only be set by clients" means. This error occurs regardless of whether I put the string in double quotes in the set command.

 

Here's the whole config. Any help is appreciated, especially if you've gotten DHCP working through a router. My other option is to forward all DHCP to the server using DHCP relay (which I assume works the same way as IOS forward-protocol), but I would much rather confine broadcasts to the local subnet. It doesn't help that Novell does all this bizarre multi-step boot stuff:

 

{master:0}[edit system services dhcp]
wms2@ccf4200stack# show
domain-name stmarys-ca.edu;
name-server {
[etc]
}
wins-server {
[etc]
}
boot-file dinic.sys;
next-server 149.137.1.142;
traceoptions {
    level info;
}

pool 10.3.1.0/24 {
    address-range low 10.3.1.100 high 10.3.1.249;
    router {
        10.3.1.254;
    }
    option 60 string PXEClient;
}
 

 

 

 

The error seems to be generated because at least according to RFC2132. Option 60 is an option passed up from the client to the DHCP server, not the other way round.

 

However , this document, however: http://www.markwilson.co.uk/blog/2004/03/configuring-dhcp-option-60-for-pxe.htm, implies Option 60 can be set on the server as well,  as an instruction to the client to so something.

 

Has anyone seen a document that describes in detail how to configure a JunOS DHCP pool to pass the proper params to a client that is one of these funky non-standard (Novell, Altiris, etc) boot clients?

 

 

Yes, this is an option the EX shoudl be able to supply, my Dell laptop clients are including Option 60 ("Vendor Class Identifier") in the list of requested options in the first DHCP Discover packet's Parameter Request List.

I've opened a support case for this and will report back.

The point of this exercise was to use the local EX switch as a DHCP server and to not use DHCP-relay. We are setting up DHCP pools on every switch port on campus, each port with its own RFC1918 private address space. Ports are aggregated into an OSPF stub area on each edge switch, which works very nicely. Managing the DHCP server on the EX's - we hope - will be easier than using a central DHCP service with 2000+ pools.The rub was getting clients to net boot off our weird and badly documented, Novel Zenworks image server.

 

Novell Zen asks us to set a cetain value of Option 60 on the DHCP server. But in JunoOS, I am not allowed to set up option 60 (or option 82) parameters in the DHCP server. According to the RFCs, Option 60 should only be set by a client, and Option 82 should only be returned by a DHCP Relay service. IOS lets me set these parameters, but I've never actually confirmed that this works.

 

As it happens, the Novell Zenworks image server uses some undocumented private DHCP options, I figured this out by snooping a successful net boot. Unlike a Linux boot which just boots pxelinux and away you go, the Zen boot requests three separate image files via DHCP during the boot process. The undocumented private dhcp options seem to control this process. The setting that finally worked for us are:

 

boot-file dinic.sys;
next-server <address of image server on distant subnet>;
option 180 ip-address <address of image server on distant subnet>;
option 181 ip-address <address of image server on distant subnet>;
option 182 ip-address 0.0.0.0;

 

In addition to the usual domain-name, default router, name-server, etc params. HTH, especially someone else who is afflicted with a Novell Zenworks environment. -w