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New Member

spantree portfast

I have some clients that are unable to get a DHCP address during the PXE boot. The clients are directly connected to a 48-port switch module on a Cat4006 chassis. I have enable spantree portfast on all ports that the clients are connected to. IP Helper is also configured on the vlan interface. Is there an additional configuration needed on the port or switch for PXE to work. Is it that this is not possible on the switch?

Thanks in advance.

  • Other Network Infrastructure Subjects

Re: spantree portfast

Switch would just switch the packets back and forth, most of the issue I have encountered with PXE is with the DHCP server itself or the PXE server. Please check the following suggestions:

option 60 is for PXEClient and Option 43 is for a set of parameters

including the IP of the server.

option 60 ascii PXEClient

option 43 hex your_hex_string_goes_here

Here's the PXE specification:

Here's a link from Intel (PXE creators) that references several vendors

This is a nicer link about how to create the binary string:

Please rate helpful posts.

New Member

Re: spantree portfast

Thank you for your response.

I will test these options and will go from there. Unfortunately I will not be able to test until next week.

I would like to add something that I should have added in my first post. I have other clients that are on the same vlan but just not directly conencted to the switch module on the chassis. They are connected to a 3500XL switch and then fiber to the chassis. Ports on the 3500XL switch are set to portfast. These clients are able to pickup a DHCP address fine. Which leads me to believe that the DHCP and PXE Server are configured correctly. Is it that clients that are connected to the switch module need these options set? Also, once the troubled workstations boot into the operating system, they are able to pick an address.

Let me know if you have any thoughts on this. I will look into the dhcp options.

Thanks again

Re: spantree portfast

One thing you can do is to connect this same client having problem to the switch where you said clients are not having problem. I do not think it is a switch specific issue but this is one way you can confirm. If the same clients having problem in the 4006 is also having problem while connected to 3500XL then that would tell you that the problem is not switch related. compare the clients not working and the ones working such as their settings.

New Member

Re: spantree portfast

I ended up adding an access switch (3500XL) and connected the troubled clients there instead of to the chassis. I am uplinking that switch to the chassis using fiber. All works fine that way. There is nothing wrong with the clients. There is something on the chassis switch module's configuration that I may be missing. This will be my permanent solution, but I would like to figure out what the issue is regardless.

Thanks in advance.


Re: spantree portfast

What command did you use to enable portfast on the 4006 . I have seen in the past in certain situations that portfast may not work (most cases it does ) , try using the command "set port host" on all client user ports , this will also turn off any trunking and channeling on the ports which adds to the delay on port activation.

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