We have a subsystem of specialized code dedicated to networking as a client to other servers (egress). It lives mostly in src/mongo/executor/ with some additional parts in src/mongo/client/.

Notable classes include (but are not limited to):

• NetworkInterface
• NetworkInterfaceTL
• TaskExecutor
• RemoteCommandResponse
• RemoteCommandRequest
• executor::ConnectionPool
• EgressTagCloser
• AsyncDBClient

There are a few distinct topics to speak to:

• Remote Commands
• Connection Pooling
• Legacy Networking (DBClient et al)

Egress networking is notably used across our codebase and lives in several directories, we should document it with a new markdown file in docs/.

This is intended to be abstract documentation, describe relationships and state transitions not code in common language.