[afnog] help on pxe boot

[Brian Candler]

On Thu, Sep 30, 2010 at 01:49:51AM -0700, teklay gebremichael wrote:
>     since we are planning to have computer lab with old pcs that will boot
>     from the server, this problem is very critical. is there some thing
>     enabled by default on the switch that prevents booting from the
>     network?

It's likely that the PC is enabling the NIC and then sending out boot
packets while the switch port is still blocking (non-forwarding).

Try setting "spanning-tree portfast" on all the PC-facing ports, or (more
risky) if this switch only has one uplink into the rest of your
infrastructure you could turn off spanning tree altogether.

There's quite a good description of the issue here, together with hints on
both CatOS and IOS configs:
http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00800b1500.shtml

HTH,

Brian.