[c-nsp] My sham-links disappeared?

[Code Monkey]

Hi,

I just upgraded a 7206 NPE 300 router running IOS (C7200-JK9S-M),
Version 12.2(15)T17 to an NPE G1 running (C7200-JK9S-M), Version
12.4(16).

I changed nothing in the configuration except for the interface names
(Fa0/0 bacame Gi0/1).

I was sure the new one had all that the old one had, I had tested it,
and almost everything is perfect -- except that the OSPF sham-links
with the other routers won't establish themseves. I hadn't checked
*that*, of course.

They don't show at all in sh ip ospf 10 neighbors, they do show as
"up" in sh ip ospf 10 sham, but the description stops with Hello and
so there is no Adjacency State FULL.

I've double and triple checked that the distribution is OK, yes, in
each vrf there is a loopback, the IP address for the loopback is the
router id, those IP addresses are not distributed into OSPF, there is
a B in front when I show route, and... and... what else? When I debug
ip ospf, I see both sides sending hellos over the OSPF_SLxx, but
nobody receiving any.

The exact same config worked fine with the old NPE and the old IOS.
I'm afraid that downgrading the IOS will shutdown the interfaces, so I
can't do that right now.

For a moment I thought it might be the MTU on the gigabit interfaces,
but that wasn't it.

I've done a diff on the configs before and after, the only changes I
can see are cosmetic (tag-switching becoming mpls)

Is there a compatibility issue between the IOSes? What can I do?
Thanks for any help.