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Routing Tag Description

IP.com Disclosure Number: IPCOM000038477D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Blanc, A: AUTHOR [+2]

Abstract

This mechanism is used in a high performance network composed of traditionnal network access nodes connected through one or several frame switching nodes (FSNs) which realize the network transit function. The main characteristics of the FSN are: . Multiplexing of HDLC (high level data link control) frames of variable length. . Routing of the incoming HDLC frame to the selected output line according to the routing tag information included in the transmission header of each frame. No error recovery. . Frame drop in case of overflow. The problem is to design a routing tag which can be easily calculated by the network access node, and decoded by the frame switching node.

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Routing Tag Description

This mechanism is used in a high performance network composed of traditionnal network access nodes connected through one or several frame switching nodes (FSNs) which realize the network transit function. The main characteristics of the FSN are: . Multiplexing of HDLC (high level data link control) frames of variable length. . Routing of the incoming HDLC frame to the selected output line according to the routing tag

information included in the transmission header of

each frame. No error recovery.

. Frame drop in case of overflow. The problem is to design a routing tag which can be easily calculated by the network access node, and decoded by the frame switching node. Moreover, the routing must be easily adapted to alternate routing (for RAS and network load purposes) without any problem of hierarchy. The routing tag is composed of a routing tag window (RTW) (1 byte) and several routing tag fields (RTFs) (2 bytes each). The routing tag window gives the number of nodes through which the message will be transferred. The routing tag field contains the physical address of the node (1 byte) and the physical address of the output line in the node (1 byte). For instance, a message to be transferred from network access node (1) to network access node (2) may have the following routing tag: a routing tag window RTW = 1, and two routing tag fields RTF1 and RTF2, RTF1 loaded with FSN(A) output address AdA1 and RTF2 loaded with FSN(D) output address Ad...