ERS4950 / FOG Server

[charles_holbro1]

Currently, I am working with a school district that replaced all of their existing ERS 5500’s with new ERS 4900’s.  The issue they are having is when the 5500’s were in place their existing centralized FOG server worked flawlessly however with the introduction of the 4900’s this is no longer the case.  When the workstations PXE boot they pick up their ip address and run through the normal procedure however once they go to udhcpc they no longer get an address and fail.  I have read a few articles in regard to this and saw a few things about using rstp instead of mst for spanning tree since the issue is related to the port not reinitializing fast enough for the second DHCP address request.  I have seen where it is possible to switch the spanning tree mode from mst to rstp, I wanted to see if anyone had ran into a similar problem before I make this change and possibly break a few things.  Currently the switch is running software version 7.6.3.021 with a single vlan at this time but will be expanding in the near future with a voice vlan.  Any suggestions are greatly appreciated.

One thing I failed to mention above I did have a mini dumb switch in between the workstation and the ERS4950 and it did PXE boot correctly and image the workstation.

[EXTR_Paul]

The default STP type was changed from the ERS5500 to 4900/5900.  But I don’t think that it is your issue.  Unless you are interconnecting the ERS550s to the 4900 for a phased migration.

If the end nodes aren’t getting an DHCP address I suspect there is something wrong with the DHCP setting on the 4900s.   But if the work stations are getting an IP and the FOG server isnt working I suspect there is something wrong with Multicast.

Were the 5500s L2 only or were they routing?

Perhaps you can share the working config from your ERS5500 and a 4900 config for comparison.