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isp
Expert
2–7 min

T-ISP-006 · BGP Path-Selection Analyzer

Explain why a given prefix's best path was chosen by replaying the BGP decision process (weight, local-pref, AS-path, origin, MED, eBGP>iBGP, IGP metric, router-id) across candidate paths.

Cisco IOS-XR
Cisco IOS/XE
Juniper Junos
Open in GeneratorOpen in Platform
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Capabilities

  • Full decision-process replay
  • Per-step winner annotation
  • Multipath candidate detection
  • MED/LP anomaly hints
  • Human-readable rationale
  • Machine-readable JSON

Required inputs

Parameters the script accepts. Defaults shown; some are vendor- or context-gated.

ParameterTypeDefaultNotes
Prefix to analyze
prefix
string203.0.113.0/24—

Hint 1 — Name your vendors and OS versions

Mention the exact platforms you run (Cisco IOS-XR, Cisco IOS/XE, Juniper Junos) so the generated isp & peering logic uses the right CLI/NETCONF syntax.

Hint 2 — State your real thresholds

Provide concrete values for Prefix to analyze instead of the defaults — they shape what counts as a fault.

Hint 3 — Prioritize the checks you need

This tool can full decision-process replay and per-step winner annotation. Ask for the subset relevant to your incident to keep output focused.

Hint 4 — Describe your inventory format

Tell the assistant whether your device list is CSV, YAML, or JSON and which columns it has, so parsing matches your data.

Sample inventory schema

Authoritative shape of the device/policy data this script consumes.

No bundled inventory sample. The script accepts standard device lists (CSV/YAML) with hostname, mgmt IP, vendor, and credentials.

Expected output

Reference terminal output the script should produce — used as a stylistic and structural target.

terminal
2026-06-15 14:00:09 INFO  Analyzing 203.0.113.0/24 (4 candidate paths)
2026-06-15 14:00:09 INFO  Step 2 local-pref: path via AS64500 wins (200 > 100)
2026-06-15 14:00:09 INFO  Best path: 198.51.100.7 (AS64500) — chosen on local-pref