Hmm, very frustrating, that's exactly the setup I'm using (although not on a Brocade DHCP server.) My TFTP server is the same machine as the default gateway. I've tried a few variations such as option 150 instead of 66, and still no luck. Thanks for going through the trouble though!
As for why the config gets downloaded, I know the switch defaults to pulling a config from its gateway, so my hunch is that the TFTP server address included in the DHCP reply is being ignored completely by the switch. This would possibly explain why it doesn't even try to download the manifest file.
It's a shame you aren't able to pull a packet trace since it's just a
switch-to-switch communication. There must be something different
getting sent by the Brocade DHCP server.
Just noticed you were asking about DHCP server config, but as I said I do not use switches for DHCP serving. Here's what a reply looks like:
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Offer
Server-ID Option 54, length 4: 172.16.0.1
Lease-Time Option 51, length 4: 6721
Subnet-Mask Option 1, length 4: 255.255.255.248
Default-Gateway Option 3, length 4: 172.16.0.1
Domain-Name-Server Option 6, length 4: 192.168.242.200
TFTP Option 66, length 10: "172.16.0.1"
TFTP-Server-Address Option 150, length 4: 172.16.0.1
BF Option 67, length 21: "FI08070a_Manifest.txt"