The customer reported that the segment-routing strict-spf (Algo-1) labels are missing in the routing table for some non-Juniper nodes in the all segment-routing domain
ISIS will ignore the strict-SPF (Algo-1) segment identifier (SID) advertised by the nodes if the ISIS Link State Packet (LSP) fragment-ID number for that node which containing the Algo-1 prefix SID is lower than the ISIS LSP fragment-ID number containing router capability TLV. For example, in the below outputs, a non-Juniper node advertised the Algo-1 SID prefix in LSP fragment-ID 00 and the Router Capability in fragment-ID 02 this will cause stric-spf (Algo-1) label to be ignored and not installed in the routing table root@R3>show isis database R1 extensive <..> R1.00-00 Sequence: 0x113a1, Checksum: 0x3e41, Lifetime: 64033 secs IPV4 Index: 1028 IPV4 Index: 28 IPV4 Index: 2028 <..> R1.00-02 Sequence: 0x929f, Checksum: 0xc5d0, Lifetime: 64032 secs <..> TLVs: Router Capability: Router ID 192.168.100.33, Flags: 0x00 SPRING Capability - Flags: 0x80(I:1,V:0), Range: 32000, SID-Label: 16000 Node MSD Advertisement Sub-TLV:Type: 23, Length: 2 Unknown MSD:Type: 1, Value: 7 SPRING Algorithm - Algo: 0 SPRING Algorithm - Algo: 1 SPRING Algorithm - Algo: 128 <..>
The fix should be in PR 1797479