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Temporary Relief From Addressing Problems

IP.com Disclosure Number: IPCOM000045969D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 6 page(s) / 81K

Publishing Venue

IBM

Related People

Ryder, KD: AUTHOR

Abstract

A technique for merging SNA (System Network Architecture) networks is described. The technique allows address-space isolation between interconnected SNA networks. At the same time, full resource sharing and communication between those networks is retained. These effects are achieved by providing address transformations at the boundaries between interconnected networks. The algorithm for executing these transforms is called TRAP (Temporary Relief from Addressing Problems).

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Temporary Relief From Addressing Problems

A technique for merging SNA (System Network Architecture) networks is described. The technique allows address-space isolation between interconnected SNA networks. At the same time, full resource sharing and communication between those networks is retained. These effects are achieved by providing address transformations at the boundaries between interconnected networks. The algorithm for executing these transforms is called TRAP (Temporary Relief from Addressing Problems).

TRAP is implemented via modifications to the ACF Network Control Program (ACF/NCP). This software operates in an IBM 3705 Communications Controller.

The interconnected network environment merges two basic network types. There is a single backbone network, supporting the TRAP capability. There are multiple attached networks which are logically and physically connected to the common backbone. These connection points are referred to as TRAP Nodes.

Flows and functions which operate across a network boundary are referred to as cross-network. A flow from the backbone network to an attached network is outbound. A flow from an attached network to the backbone network is inbound.

An overview of the multi-network environment is provided by Fig. l.

The TRAP function causes the backbone network and attached networks to perceive a physical and logical environment which is different from the actual configuration. This difference in perception leads to the Pseudo Node concept. A Pseudo Node appears as a Communications Controller which is interposed between one or more attached networks and a TRAP Node.

A Pseudo Node manifests itself to each attached network as part of the address space of that attached network. To the backbone network, a Pseudo Node appears as part of the backbone network address space. Each TRAP Node has one or more backbone network Pseudo Nodes associated with it.

Physical connectivity between a TRAP Node and each attached network consists of one or more links. To the backbone network, all connectivity outboard of a TRAP Node is represented by a single Pseudo Link. This Pseudo Link provides a single link appearance for purposes of outbound traffic routing.

Although attached networks perceive Pseudo Nodes, they have no need for a Pseudo Link view of physical connectivity. Each communications Controller node in an attached network is limited to a single physical connection to the backbone network. Hence, for attached networks, there is a complete correspondence between perceived and actual links.

The TRAP Node Table (TNT) is a table containing the attached network addresses of all attached network resources which can be accessed through a particular TRAP Node (Fig. 2). A TNT is unique to a given TRAP Node. Its content is determined by the attached networks which are directly connected to that TRAP node. The TNT contains separate segments for each attached

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network link. Within each segment of the TNT, the a...