feat(srv6): SRv6-native (DSR) ClusterIP Services#1043
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/codebuild_run(29cbaed) |
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CI complains with the following errors: @ryskn Can you please run |
Replace cnat DNAT/un-DNAT with Direct Server Return for pod-backed ClusterIP services in the SRv6 data path. Traffic keeps dst=VIP end to end; backend pods accept the VIP on lo and reply from it, so no reverse translation is needed and the cross-node SRv6 un-DNAT failure disappears. Source IP is preserved (no SNAT). - config: SRv6NativeServicesEnabled feature gate + vppSRv6Native annotation - services: classify eligible ClusterIP services (gate + annotation + ClusterIP + port==targetPort), skip cnat, publish DSRService events, reconcile-based diff/withdraw - connectivity/SRv6: per-service ECMP SR policy over backend nodes' End.DT6 SIDs + steering; decap into PodVRF via sw_if_index; reconcile with retain-on-failure retry and periodic re-reconcile - cni: bind VIP on local backend pods (lo) + uRPF allow + PodVRF ECMP delivery route; per-pod cleanup tracking; reconcile on pod add/del Experimental; requires SRv6Enabled. Other services (NodePort/External, port-remapped, host-network backed) keep the cnat path. Signed-off-by: Ryosuke Nakayama <ryosuke.nakayama@ryskn.com>
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thanks! |
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/codebuild_run(c146809) |
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Summary
Adds an opt-in SRv6-native data path for pod-backed ClusterIP Services that
uses Direct Server Return (DSR) instead of cnat.
In an IPv6 single-stack + SRv6 setup, cross-node pod-backed ClusterIP Services
break: cnat's reverse session lives in the main FIB and the
cnat-lookupinputarc never runs on the SRv6-decapped inner packet, so the reply is never
un-DNAT'd (the SYN-ACK keeps the backend Pod IP → client RST). This is the
pod-backed counterpart of the host-network case fixed in #1028.
Approach
Rather than make cnat compose with SRv6, steer the VIP over SRv6 and let the
backend accept it directly (DSR): the inner packet keeps
dst=VIPend to endand the backend replies with
src=VIP, so no reverse translation is needed.Source IP is preserved.
srv6NativeServicesEnabled+ Service annotationcni.projectcalico.org/vppSRv6Native: "true". Eligible = ClusterIP, all portsport==targetPort, pod-backed. host-network / port-remapped / External-LBServices keep the cnat path.
End.DT6SIDs + steering;backends bind the VIP and are allowed through uRPF; PodVRF delivery route.
Reconcile-based, no NAT on the path.
Verified end to end on an IPv6 single-stack cluster: cross-node client reaches
the VIP with no cnat, no RST, and the client source IP preserved.