Confirm neighbor reachability with TCP ACKs

As per RFC 4861 section 7.3.1,
  A neighbor is considered reachable if the node has recently received
  a confirmation that packets sent recently to the neighbor were
  received by its IP layer. Positive confirmation can be gathered in
  two ways: hints from upper-layer protocols that indicate a connection
  is making "forward progress", or receipt of a Neighbor Advertisement
  message that is a response to a Neighbor Solicitation message.

This change adds support for TCP to let the IP/link layers know that a
neighbor is reachable.

Test: integration_test.TestTCPConfirmNeighborReachability
PiperOrigin-RevId: 354222833

0 files changed, 0 insertions, 0 deletions