Symptom

The next-hop leaf list pushed-label-stack is being presented in the original FIB order, which considers Top -> Bottom. The OC-AFT model specifies that the rightmost label in the list should be the top, hence they use Bottom -> Top order. The output we're getting is in Top -> Bottom order in the oc-aft collections. We have issue where pushed label ordering is incorrect. We are getting SRTE pushed label stack top to bottom but according to OC-AFT model instructions are bottom to top. Please advise. https://github.com/openconfig/public/blob/master/release/models/aft/openconfig-aft-common.yang - the stack is encoded as a leaf list whereby the order of the entries is such that the first entry in the list is the label at the bottom of the stack to be pushed. To this end, a packet which is to forwarded to a device using a service label of 42, and a transport label of 8072 will be represented with a label stack list of [42, 8072]. SRTE B-SID CLI RP/0/RP0/CPU0:GOOGLE_AS_5508-3#sh segment-routing traffic-eng forwarding policy binding-sid 465500 Thu May 26 09:27:56.006 EDT SR-TE Policy Forwarding database -------------------------------- Color: 1000, End-point: :: Name: srte_c_1000_ep_:: Binding SID: 465500 Active LSP: Candidate path: Preference: 10 (configuration) Name: CORTEX1 Local label: 24525 Segment lists: SL[0]: Name: CORTEX1_1 Switched Packets/Bytes: 0/0 Paths: Path[0]: Outgoing Label: 400020 Outgoing Interfaces: Bundle-Ether506 Next Hop: 220.1.1.5 Switched Packets/Bytes: 0/0 FRR Pure Backup: No ECMP/LFA Backup: No Internal Recursive Label: Unlabelled (recursive) Label Stack (Top -> Bottom): { 400020, 400040 } FIB CLI ENCAP => [afi:ipv4, proto:mpls, ref:3, flags:[owner locked, pi only], nh:0x309eed0dc0(NHINFO), main_obj:0x309fd78cd8(TEP)] obj-id:[0x1000002008006ca1][0x309fb4e128] NHINFO => [type:tx, linkt:link_MPLS, nh_proto:IPv4, ifh:Bundle-Ether507(0x200090ac), nh:220.1.1.7, adj:0x3090b3e308, flags:[owner locked, pd bind pending] flags2:[]] obj-id:[0x10000020100017f8][0x309eed0dc0] LABEL_INFO => [stack [o-label:{400020 400040} ifh:0x20008fac l-label:24525 type:17 flags:[linked to lsw, ipv4, srte] ext-flags:[te-stack] stats-key:[0x5fcd00000001] pd-enc-id:0x13e8c00000001]] obj-id:[0x10000020100058c0][0x309fa07d48]] ST Collection openconfig-network-instance/network-instances/network-instance/default/afts/next-hops/next-hop/1152922329240570168/state/index, 1152922329240570168, 2022-04-08-16:39:30.241283002 openconfig-network-instance/network-instances/network-instance/default/afts/next-hops/next-hop/1152922329240570168/state/ip-address, 216.1.1.2, 2022-04-08-16:39:30.241283002 openconfig-network-instance/network-instances/network-instance/default/afts/next-hops/next-hop/1152922329240570168/state/pushed-mpls-label-stack, [400020 400040], 2022-04-08-16:39:30.241283002 openconfig-network-instance/network-instances/network-instance/default/afts/next-hops/next-hop/1152922329240570168/interface-ref/state/interface, Bundle-Ether108, 2022-04-08-16:39:30.241283002 This should be Bottom -> TOP openconfig-network-instance/network-instances/network-instance/default/afts/next-hops/next-hop/1152922329240570168/state/pushed-mpls-label-stack, [400040 400020], 2022-04-08-16:39:30.241283002

Conditions

Workaround

Further Problem Description

This issue affects 7.3.4 FCS image on NCS5500/8000/ASR9K platform. Issue will be resolved by SMU. Other releases are not affected by this issue.