doc:LRP skipRedirectFromBackend with per packet LB

[MitchLewis930]

PR_042

[MitchLewis930]

@greptileai

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Greptile Overview

Greptile Summary

Updated documentation to reflect that the skipRedirectFromBackend configuration for Local Redirect Policy now supports per-packet based load-balancing in addition to socket-based load-balancing.

• Changed line 534 from "only supported with socket-based load-balancing" to "supported with socket-based load-balancing and per packet based load-balancing"
• This documentation change aligns with the BPF code implementation in commit 3c85f0e which added LRP loopback fix for non-socket LB mode
• The implementation uses the cilium_skip_lb4/6 maps with netns cookies to skip service translation when packets originate from local redirect backend pods
• Tests were added in bpf/tests/skip_lb_xlate_lrp_per_packet_lb.c to verify the per-packet LB behavior

Confidence Score: 5/5

• This PR is safe to merge with no risk - it only updates documentation to match existing code functionality
• The documentation change accurately reflects the BPF implementation added in commit 3c85f0e, which extended skipRedirectFromBackend support to per-packet load-balancing. The change is minor, well-supported by code and tests, and involves no functional code changes
• No files require special attention

Important Files Changed

Filename	Overview
Documentation/network/kubernetes/local-redirect-policy.rst	Updated documentation to reflect that skipRedirectFromBackend now supports both socket-based and per-packet load-balancing modes

Sequence Diagram

sequenceDiagram
    participant Backend as Backend Pod
    participant BPF as BPF Datapath (lb4_local/lb6_local)
    participant SkipLBMap as Skip LB Map (cilium_skip_lb4/6)
    participant Service as Service Frontend
    participant OtherBackend as Other Backend Pod
    
    Note over Backend,OtherBackend: skipRedirectFromBackend enabled for LRP
    
    Backend->>BPF: Packet to Service IP:Port
    BPF->>BPF: Check if service has SVC_FLAG_LOCALREDIRECT
    BPF->>SkipLBMap: Lookup (netns_cookie, service IP, source port)
    SkipLBMap-->>BPF: Match found
    BPF->>Service: Forward to original frontend (skip translation)
    Note over BPF,Service: Packet NOT redirected back to Backend
    
    Note over Backend,OtherBackend: Alternative: Without skipRedirectFromBackend
    
    Backend->>BPF: Packet to Service IP:Port
    BPF->>BPF: Apply LRP backend selection
    BPF->>Backend: Redirect back to Backend (loopback)
    Note over Backend: Creates loopback issue

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