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Cross-vendor lab work on the fabric layer: EVPN ESI multihoming between Cumulus and Arista, BGP unnumbered underlays, and the parts of it that only show up when you capture the traffic instead of trusting show output.
AI Networking pinned
Four leaves, two vendors, one Ethernet Segment. Five configuration differences between Cumulus and Arista stand between the RFC and a working all-active bond — four get solved here, and none of them are in the RFC.
AI Networking pinned
RA drives dynamic peer discovery in BGP unnumbered — and turning it off tears down established sessions instantly, with no flap and no timeout. Why, and what the ND cache does and does not tell you.
2,000 CE-marked packets in, 2,000 CNPs out. A byte-level look at a real ConnectX-5 CNP, the NIC rewriting ECN behind my back, and the DCQCN roles that soft-RoCE was missing.
tc marks 3,682 packets CE. All 3,682 arrive at the receiver. Soft-RoCE sends back zero CNPs. Where the line falls between what you can verify in software and what needs hardware — and how I nearly got the answer wrong.
The control plane agrees on the Designated Forwarder and the host still receives every broadcast twice. Multi-point captures, a same-vendor control group, and a packet capture that was quietly lying.
Arista and Cisco NX-OS, an unnumbered eBGP session, an IPv4 route installed with an IPv6 next hop — and no forwarding. The fix is one interface command, and the reason is RFC 8950.