Odd blocked packets

I have been unable to decifer what this blocked packet is.

14/07/2006 12:00:09.147627 pppoe0 @0:4 b x.x.224.1 ->
y.y.0.5 PR ospf len 20 (64) IN low-ttl

Rule 4 is as follows:

# Block in any packets that are not heading to my IP
block in log quick on pppoe0 from any to !x.x.226.32/32 head 11
#Unless they are destined for my NAT'd subnet (nat occurs before filtering)
pass in on pppoe0 from any to 192.168.1.0/24 group 11

x.x.224.1 - This is the first gateway I hit on my DSL
line on the way to my ISP

y.y.0.5 - This is some address I know nothing about. On a subnet
unrelated to my subnet (not even close).

My IP is x.x.226.32 - same subnet as the gateway otherwise.

So what is protocol "ospf"?

I started getting a bunch of these (thousands per hour, but not
significant bandwidth) about a week ago and it continues
to this day. My ISP is investigating, but it would help if
I could tell them what this is, or even speculate...

Thanks,
gene