Glossary

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Automated Repeat-reQuest (ARQ): Packets are identified by a sequence number and acknowledged by the receiver. Lost packets are retransmitted, usually after receiving a number of duplicate ACKs or a certain timeout.

Bind: The action of associating a name with a program or process. A process bound to a name will respond to incoming flow allocation requests for that name in that system. If a program is bound to a name, all subsequently instantiated processes will be bound to that name.

Broadcast Flow: A broadcast flow is the abstraction for a packet stream that is sent from a source node to a set of nodes. A Broadcast Flow is implemented by a Broadcast Layer.

EFCP: The protocol inside RINA IPCPs that is responsible for enabling IPC. It is a 2-component protocol consisting of the Data Transfer Protocol (DTP) and a Data Transfer Control protocol (DTCP) which share a state vector.

Enrollment: The action of adding an IPCP or a set of IPCPs to a Layer as an active member.

Flow: A flow is the abstraction for a packet stream between a number of application processes. Ouroboros makes a clear distinction between Unicast flows and Broadcast flows.

Flow Allocator: The component in the IPCP that is responsible for flow allocation, managing flow state and congestion avoidance.

Flow Descriptor: A handle used by an application to manipulate and read/write from/to flows, similar to a file descriptor for files.

Flooding: The algorithm that takes a packet on the incoming flow and then sends it out on all other (outgoing) flows. Flooding is the main algorithm implemented by the Data Transfer component of a Broadcast IPCP.

Forwarding: Any algorithm that takes as input a destination address and gives as output a set of flows. The forwarding algorithm is the main algorithm in the Data Transfer component of the unicast IPCP.

Inter-Process Communication Resource Management Daemon (IRMd): The IRMd is the central daemon that performs management functions for Ouroboros. It listens for management commands such as creating/destroying IPCPs, bootstrapping and enrolling IPCPs, binding programs and processes to service names and registering names with an IPCP.

IP fragmentation problem: Retransmission logic is handled by TCP, so the loss of an single IP datagram results in the retransmission of all the fragments constituting a (potentially much larger) TCP frame, instead of just this lost datagram.

Layer / layer: The Ouroboros model is subdivided in layers (lowercase), with similar intent as the TCP/IP model (5 layers) or OSI (7 layers) model which it aims to improve upon.; Ouroboros is multi-Layered (capitalized), allowing networks to overlay each other. There are 2 types of Layers: Unicast Layers and Broadcast Layers, consisting of Unicast IPCPs and Broadcast IPCPs respectively. Note that they can't be mixed (a Unicast IPCP can't enroll with a Broadcast IPCP), but it is of course possible for a program to implement both the Unicast and Broadcast IPCP functionality. The different use of layer/Layer can be initially confusing, and have considered other options such as stratum, but for the time being, we stick to Layer / layer.

Name: also known as Service Name; A non-descript string of characters in some namespace that can be bound to a program or process.

Process: In the Ouroboros framework, the instantiation of a program. It is logically identified by a local Process Identifier (PID), which on POSIX systems maps directly to the process ID (pid).

Program: In the Ouroboros framework, the code (for instance a compiled binary or a script) that can be executed as a Process.

Raw Flow: A best-effort Unicast Flow between two peers without any QoS guarantees.

Routing: Any algorithm that can construct a distance function to all other nodes in a Unicast Layer. The literature discerns at least 3 classes of Routing algorithms: geometric, link-state and distance/path-vector.; The output of a routing algorithm is needed to construct a forwarding algorithm. The routing algorithm is the main algorithm in the routing component of the unicast IPCP.

Unenrollment

The action of removing an IPCP or a set of IPCPs to a Layer.

Unicast Flow: A unicast flow is a point-to-point packet stream between two processes. A flow is identified at each end by a flow descriptor. A unicast flow is implemented as a network flow between two unicast IPCPs. A network flow is identified by a 4-tuple <source address, source EID, destination address, destination EID>. The Endpoint Identifiers (EIDs) are agreed upon during Flow Allocation. A Unicast Flow is not implying an application protocol.

Whatevercast: A proposed RINA concept for the unification of unicast, anycast, multicast and broadcast. The RINA DIF will resolve the correct set of destination nodes based on the whatevercast name and a set of rules associated with it. Our attempt at implementing whatevercast led to us formulating the Ouroboros multicast conjecture.

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