[c-nsp] help on pxe boot

[teklay gebremichael]

hello,
I have a session server for thin clients to connect to.  the session server has 2 NICs(one connecting to the organization switching infrastucture and the other one to the thin client network/subnet only). i have connected one cisco 2960 switch (new switch with default confg) to connect the sun rays and the thin  stations to the server.
sun ray DTUs are working perfectly.

I have also thin stations that are connected to the session server like the sun rays.
with the thin station, the pxe boot doesn't work on the first trial and works on the second boot. again i tried tried with old pcs to boot from the server and yet not working at all.

but, i took another scenario that i have connected the server directly to the thin station  with out a switch and it boots on the first trial and the boot process is a bit faster.
and i tried it with the old pc and it is able to boot from the server directly with out the switch in between.

again i tried the case with another cisco switch and i got the same thing (not working).

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?

i appreciate your help in advance.

regards,
Teklay