I'm trying to get a GRE tunnel up between my home network and my office
network so I can get multicast between the two.

Here's what I've got

Home:
NetBSD/i386 1.5_BETA (Haven't had the burning desire to upgrade the
kernel yet)

ifconfig gre0 204.192.127.178 208.184.7.43 netmask 255.255.255.255
ipforwarding is enabled via sysctl.
Running pimd with BROKEN_CISCO_CHECKSUM compiled in.
System is also running gif0 as an IPv6 tunnel to freenet6.net

Office:
Cisco 7206

interface Tunnel50
 description mbone tunnel to home
 ip unnumbered FastEthernet0/0
 ip pim bsr-border
 ip pim sparse-mode
 ip multicast ttl-threshold 64
 tunnel source FastEthernet0/0
 tunnel destination 204.192.127.178
end

FastEthernet 0/0 is 208.184.7.43

The Cisco shows the tunnel interface to be fully up until I try to pass
traffic across it, then it drops to "line protocol is down".

Obviously I'm missing something...any suggestions?