Implementation reports for https://datatracker.ietf.org/doc/draft-ietf-idr-bgp-sendholdtimer
Two test tools have appeared in the ecosystem:
disable rx option, this option discards received messages and disables the hold timer (this option only exists for testing purposes!)One way to trigger the SendHoldTimer is to reply to each packet with a TCP-recv-window of 0; all the while sending BGP KEEPALIVE messages. After some time the system write buffer fills up and the BGP implementation can recognize messages are not making it across the wire.
Tested against bgp-zerowindow-test.
SendHoldTimer event implementation https://github.com/openbsd/src/commit/ab9b1ccdd3ae2f6b9b7be622908bbd31ddeef78a
Tested against bgp-zerowindow-test.
https://github.com/FRRouting/frr/pull/11225
https://github.com/FRRouting/frr/pull/12142
Tested against both bgp-zerowindow-test and BIRD's own disable rx option.
https://gitlab.nic.cz/labs/bird/-/commit/bcf2327425d4dd96f381b87501cccf943bed606e
Tested against bgp-zerowindow-test.
Closed source implementation.
IANA has registered code 8 for "Send Hold Timer Expired" in the "BGP Error (Notification) Codes" sub-registry under the "Border Gateway Protocol (BGP) Parameters" registry.
OpenBGPD: https://github.com/openbsd/src/commit/66500b2f7772472127e272da950033189f1a648e
BIRD: https://gitlab.nic.cz/labs/bird/-/commit/44a16bff6cbf3f5ae8db21ffcec602bc51295d0a
Patches to recognize error code 8 were merged into OpenBSD's tcpdump and the-tcpdump-group's tcpdump implementations.