Configmgr 2007 : PXE boot & MTFTP……. defaulting and make you wait for 10–15 minutes

January 13, 2011 at 6:23 pm in Uncategorized by Kenny Buntinx [MVP]

Problem :

I am trying to setup OSD at a customers site. I am having issues when trying to network boot a client.  When doing a Network boot the client picks up DHCP information correctly and then displays "MTFTP….." and the dots continue on for quite some time(about 15 min), switch over to normal TFTP and then the PC will boot into Windows PE Running the task sequence as expected.

Within Site Management->Site->Site Settings->Site Systems->ConfigMgr Distribution Point I have the box for multicast unchecked.
Within Site Management->Computer Management->OSD deployment->Operating System Images-> under my target image’s distribution settings I have "allow this package to be transferred via multicast" unchecked.

So I didn’t know where that MTFTP came from and I didn’t know why my client is defaulting to a MTFTP connection instead of a normal TFTP connection? 

Solution :

On your DHCP scope , disable or delete any option 43 as shown below in the picture and asign them to specific reservations :

image

 

Explanation :

The customer has a cisco wireless AP in place with a cisco wireless LAN controller . In the DHCP scope options the option 43 called “Vendor specific option” is set.

When Cisco’s Wirelesss Unified Architecture is deployed, the Lightweight Cisco Aironet Access Points (AP) can use a vendor specific Dynamic Host Control Protocol (DHCP) Option 43 to join specific Wireless LAN Controllers (WLCs) when the WLC is in a different subnet than the LAP. 

If I looked closer , I saw that is was a ASCII value that option 43 was representing was an IP address.

Option 60 is included in the initial DHCP discover message that a DHCP client broadcasts in search of an IP address. Option 60 is used by the DHCP Clients (LAPs in this case) in order to identify itself to the DHCP server.

In order to facilitate AP discovery of WLAN controllers that use DHCP Option 43, the DHCP server must be programmed in order to return one or more WLAN controller management interface IP addresses based on the VCI of the AP. In order to do this, the DHCP server is programmed in order to recognize the VCI for each access point type, and then define the vendor specific information.

On the DHCP server, the vendor specific information is mapped to VCI text strings. When the DHCP server sees a recognizable VCI in a DHCP discover from a DHCP client, it returns the mapped vendor specific information in its DHCP offer to the client as DHCP Option 43. On the DHCP server , option 43 is defined in each DHCP pool (Scope) that offers IP address to the LAPs . In my case the AP’s  were on the same scope as my PXE clients , and those AP’s connect to the WLC with option 43 that is using MTFTP for Access points.. Unfortunately the Bootrom of the network card doing PXE is programmed to let option 43 go first , pointing with that IP address to the Mtftp service running  on the WLC (which is in this case referring to the WLC )

 

Hope it Helps ,

 

Kenny Buntinx

Tweet about this on TwitterShare on FacebookShare on Google+Share on LinkedInPin on Pinterest