quistion about PXE boot

[Julie Xu]

Hi,

 

I have problem with one campus PXE boot.

 

Basically, when you boot a window machine normally, it can get ip addres, but if you do PXE boot, it can not get.

 

This case happens when we change network switch. Yes, it is switch issue, not dhcp.

 

But, what is different PXE boot and normally boot different?

 

On PXE boot, I can see the dhcp discover send out; I can see dhcp offer send out from dhcp server. but, the dhcp offer never pass the switch to the machine.

 

 

Any comments will be appreciated

 

Thanks in advance

 

Julie Xu

 

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[Jim Glassford]

Hi Julie,

Maybe related to dhcp snooping on layer two switch.
If PXE server is different than dhcp server, snooping would block PXE
boot. Would see this in the switch logs.
If using HP ProCurve switch running older firmware, known problems
with PXE booting with dhcp snooping enabled, upgrade or disable dhcp
snooping. (not sure of versions with problems and nothing logged was
when this happened)

best!
jim

On Sat, 9 Apr 2016 00:21:43 +0000
  Julie Xu <[hidden email]> wrote:

> Hi,
>
> I have problem with one campus PXE boot.
>
> Basically, when you boot a window machine normally, it can get ip
>addres, but if you do PXE boot, it can not get.
>
> This case happens when we change network switch. Yes, it is switch
>issue, not dhcp.
>
> But, what is different PXE boot and normally boot different?
>
> On PXE boot, I can see the dhcp discover send out; I can see dhcp
>offer send out from dhcp server. but, the dhcp offer never pass the
>switch to the machine.
>
>
> Any comments will be appreciated
>
> Thanks in advance
>
> Julie Xu
>

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[Bob Harold]

On Sat, Apr 9, 2016 at 6:40 AM, Jim Glassford <[hidden email]> wrote:

Hi Julie,

Maybe related to dhcp snooping on layer two switch.
If PXE server is different than dhcp server, snooping would block PXE boot. Would see this in the switch logs.
If using HP ProCurve switch running older firmware, known problems with PXE booting with dhcp snooping enabled, upgrade or disable dhcp snooping. (not sure of versions with problems and nothing logged was when this happened)

best!
jim

On Sat, 9 Apr 2016 00:21:43 +0000
 Julie Xu <[hidden email]> wrote:

Hi,

I have problem with one campus PXE boot.

Basically, when you boot a window machine normally, it can get ip addres, but if you do PXE boot, it can not get.

This case happens when we change network switch. Yes, it is switch issue, not dhcp.

But, what is different PXE boot and normally boot different?

On PXE boot, I can see the dhcp discover send out; I can see dhcp offer send out from dhcp server. but, the dhcp offer never pass the switch to the machine.


Any comments will be appreciated

Thanks in advance

Julie Xu

Try adding:

      always-broadcast true;

to that subnet.  Some combinations of routers and clients need that option, but it increases the broadcast traffic, so I don't just use it everywhere.  (For me, it is Juniper switches and Mac clients that hit this issue.)

-- 

Bob Harold

 

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