Reliable User Datagram Protocol

Internet protocol suite
Application layer
Transport layer
Internet layer
Link layer

In computer networking, the Reliable User Datagram Protocol (RUDP) is a transport layer protocol designed at Bell Labs for the Plan 9 operating system. It aims to provide a solution where UDP is too primitive because guaranteed-order packet delivery is desirable, but TCP adds too much complexity/overhead.

It extends UDP by adding the following additional features:

  1. Acknowledgment of received packets
  2. Windowing and flow control
  3. Retransmission of lost packets
  4. Overbuffering (Faster than real-time streaming)

RUDP is not currently a formal standard, however it was described in an IETF internet-draft in 1999. It has not been proposed for standardization.

Cisco RUDP

Cisco in its Signalling Link Terminals (either standalone or integrated in another gateway) uses RUDP for backhauling of SS7 MTP3 or ISDN signaling.

  1. RUDP v0 (no checksums) is used for SS7 MTP3 backhaul
  2. RUDP v1 (with checksum) is used for ISDN PRI backhaul

The versions are mutually incompatible and differ slightly from the IETF draft. The structure of the Cisco Session Manager used on top of RUDP is also different.

Microsoft R-UDP

Microsoft has introduced another protocol they refer to as R-UDP. It is used in their MediaRoom product for IPTV service delivery over multicast networks. This is a proprietary protocol and very little is known about its operation. It is not thought to be based on the above referenced IETF draft.

References