Hi all,
I have a network divided into 3 IGP areas:
An OSPF area that is LDP only == An ISIS Area that is SR enabled == An OSPF area that is LDP only
I'm trying to ping from one side to another but SR/LDP interworking is not working at the border between ISIS and OSPF.
Here is my setup:

All devices can see each others loopbacks. SR is enable in the middle ISIS domain with SRGB range of 16000-20000.
I'm trying to get PE1 - the second to far left device - to ping PE2 (10.1.1.102/32).
In order to get end to end reachability within the SR domain P2 acts as a mapping server and gives 10.1.1.102 the index of 102. So it should have the segment label 16102.
And indeed when I trace my way through the network, P2 (which is also in the data path), swaps the incoming label of 24001 (it's local LDP label for 10.1.1.102) with 16102 and forwards it on to R4 in the middle. R4 then carries the segment on and passes the packet to R6 with label 16102 on top.
But R6 drops the label and when I look at is LFIB it is not installed a local SR label of 16102 for 10.1.1.102 - so it just drops it. And I'm not sure why. It does have an LDP label. But no SR label.
RP/0/RP0/CPU0:P6#show mpls forwarding prefix 10.1.1.102 255.255.255.255
Mon Jul 24 23:37:23.812 UTC
Local Outgoing Prefix Outgoing Next Hop Bytes
Label Label or ID Interface Switched
------ ----------- ------------------ ------------ --------------- ------------
24016 22 10.1.1.102/32 Gi0/0/0/2 10.6.7.7 0
RP/0/RP0/CPU0:P6#
RP/0/RP0/CPU0:P6#
RP/0/RP0/CPU0:P6#
RP/0/RP0/CPU0:P6#
RP/0/RP0/CPU0:P6#sh isis segment-routing label table
Mon Jul 24 23:37:47.852 UTC
IS-IS CORE IS Label Table
Label Prefix/Interface
---------- ----------------
16002 10.1.1.2/32
16003 10.1.1.3/32
16004 10.1.1.4/32
16006 Loopback0
16077 10.1.1.77/32
16101 10.1.1.101/32
16602 2001:1ab::2/128
16606 Loopback0
16677 2001:1ab::77/128
16701 2001:1ab::101/128
RP/0/RP0/CPU0:P6#
The next hop for 10.1.1.102 is via OSPF, which is LDP only. But I would expect it to have a local label of 16102 which is would swap out with R7s LDP label as per interworking?
If I strip SR from the middle the pings work fine - end to end. Also, I've shutdown P3 and P5 interfaces so there is only one path through the network (no ECMP or anything).
Any help would be appreciated. Happy to provide full configs/output if needed.