Overview

The RSSI is based upon RUDP (Cisco implementation) RFC-908, RFC-1151, draft-ietf-sigtran-reliable-udp-00.
The specifications in the drafts are modified by internal simplifications and improvements.
Performance for RSSI + UDP:
- HW-to-HW Performance
- SW-to-HW Performance

Differences from RUDP (RFC/draft)

General deviation summary:

No auto reset functionality.
No transfer state.
No out of sequence acknowledgments (EACK).
Different header structure (see headers on figures below).
Unit for the timeouts can be set in generic. The timeout unit is also communicated in SYN header.
Value in header corresponds to (-log Unit).  Example Unit 10E-6. Value =6.
Minor deviation in re-transmission mechanism (Re-transmission mechanism below).
Improved flow control using BUSY flag (Flow control using BUSY flag below).
Handling of BUSY/flow-control implemented from server->client only (i.e., the client may signal BUSY; the server never does).
Version without re-transmissions. Implemented only in firmware transmitter module.
Software client should be implemented to "Smart" ACK even though the segments are
missing or out of order (Version with no re-transmissions below). Use cases have to be defined.
Note

Empty ACK segment contains the sequence number of the next DATA, NUL or SYN segment (As per the standard).

Uros Legat

ulegat@slac.stanford.edu