tests: fix bgp_soo topotest by separating IPv4/IPv6 address families

[enkechen-panw]

The bgp_soo topotest was flaky because IPv4 routes were being advertised over both IPv4 and IPv6 BGP sessions due to the default behavior of "bgp default ipv4-unicast" which auto-activates IPv4 unicast for all neighbors.

This caused inconsistent path counts depending on timing:

• Sometimes multiPathCount showed 2 or 3 instead of expected values
• The duplicate paths from IPv6 sessions carrying IPv4 routes caused the flakiness

Fix by adding "no bgp default ipv4-unicast" to all routers and explicitly activating only the appropriate neighbors in each address-family:

• IPv4 unicast: only IPv4 peers activated
• IPv6 unicast: only IPv6 peers activated

Update test expectations to reflect the correct path counts now that duplicate paths are eliminated.

Note: The core SoO functionality is validated by test_bgp_soo() which checks route filtering based on SoO extended community matching. The pathCount/multiPathCount changes in other tests only affect JSON output format validation, not SoO behavior. Updated docstrings to clarify this.

[greptile-apps]

Greptile Summary

This PR fixes a flaky topotest in bgp_soo by disabling the default IPv4 unicast auto-activation (no bgp default ipv4-unicast) on all four routers and explicitly activating only the correct address-family peers for each neighbor. This eliminates spurious duplicate IPv4 paths that were being carried over IPv6 BGP sessions, making path counts deterministic.

• BGP configs (cpe1, cpe2, pe1, pe2): Added no bgp default ipv4-unicast and explicit neighbor … activate statements per address-family so IPv4 peers are only active in address-family ipv4 unicast and IPv6 peers only in address-family ipv6 unicast.
• Test expectations: totalPaths in PE1 neighbor-routes views drops from 12 → 8, per-route multiPathCount drops from 2 → 1, and pathCount/multiPathCount for a few CPE1 advertised routes are reduced to reflect the now-clean single-path-per-AF topology.

Confidence Score: 5/5

Safe to merge — the change tightens address-family peer activation and updates test expectations to match; no production routing code is touched.

All five changed files are topotest infrastructure. The BGP config changes correctly apply no bgp default ipv4-unicast and re-add explicit per-AF activations, precisely matching the intended topology. The updated path counts in the Python test are internally consistent (4 routes × 2 total paths in VPN RIB = 8, single multipath per route after duplicate elimination). The core SoO filtering test logic is unchanged.

No files require special attention.

Important Files Changed

Filename	Overview
tests/topotests/bgp_soo/test_bgp_soo.py	Updated path-count expectations to match the now-deterministic topology; added module docstring clarifying which tests validate SoO behavior vs. JSON output format. Core SoO test logic is unchanged.
tests/topotests/bgp_soo/pe1/bgpd.conf	Added no bgp default ipv4-unicast to VRF RED instance and explicitly activated IPv4 peer (192.168.1.1) in ipv4 unicast and IPv6 peer (2001:db8:1::1) in ipv6 unicast. Correct and complete.
tests/topotests/bgp_soo/pe2/bgpd.conf	Added no bgp default ipv4-unicast to VRF RED instance and explicitly activated 192.168.2.1 in ipv4 unicast; IPv6 unicast already had explicit activation. Consistent with pe1 treatment.
tests/topotests/bgp_soo/cpe1/bgpd.conf	Added no bgp default ipv4-unicast and activated IPv4-only neighbors (192.168.1.2 eBGP, 10.0.0.2 iBGP) in ipv4 unicast; IPv6 neighbors are already exclusively in ipv6 unicast.
tests/topotests/bgp_soo/cpe2/bgpd.conf	Mirror of cpe1 changes: no bgp default ipv4-unicast, IPv4 peers activated in ipv4 unicast only. IPv6 neighbors correctly isolated in ipv6 unicast.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    CPE1["CPE1 (AS 65000)"]
    CPE2["CPE2 (AS 65000)"]
    PE1["PE1 VRF RED (AS 65001)"]
    PE2["PE2 VRF RED (AS 65001)"]

    CPE1 -- "IPv4 eBGP 192.168.1.x" --> PE1
    CPE1 -- "IPv6 eBGP 2001:db8:1::x" --> PE1
    CPE2 -- "IPv4 eBGP 192.168.2.x" --> PE2
    CPE2 -- "IPv6 eBGP 2001:db8:2::x" --> PE2
    PE1 -- "IPv4 VPN iBGP 10.10.10.x" --> PE2
    CPE1 -- "IPv4 iBGP 10.0.0.x" --> CPE2
    CPE1 -- "IPv6 iBGP 2001:db8:10::x" --> CPE2

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