Gigabit per-second optical packet switching with electronic control

• US 5,278,689 A
• Filed: 02/19/1993
• Issued: 01/11/1994
• Est. Priority Date: 12/19/1990
• Status: Expired due to Term

• Current Assignee: AT&T, Inc.
• Original Assignee: AT&T, Inc.
• Inventors: Haas, Zygmunt, Gitlin, Richard D.
• Primary Examiner(s): Chilcot, Jr., Richard E.
• Assistant Examiner(s): BACARES, RAFAEL D
• Application Number:
  US08/022,614
• Time in Patent Office: 326 Days
• Field of Search: 359/137, 359/128, 359/135, 359/139, 359/140, 370/84, 370/94.1, 370/94.2, 370/94.3, 370/60, 370/60.1, 370/110.1, 370/112
• US Class Current: 398/54
• CPC Class Codes: H04J 14/08 Time-division multiplex systems
• CPC Class Codes: H04J 3/22 in which the sources have different rates or codes simultaneous speech and digital data or video transmission H04M11/06; see provisional also H04J3/16
• CPC Class Codes: H04J 3/247 ATM or packet multiplexing
• CPC Class Codes: H04L 49/30 Peripheral units, e.g. input or output ports
• CPC Class Codes: H04L 49/3081 ATM peripheral units, e.g. policing, insertion or extraction
• CPC Class Codes: H04L 49/357 Fibre channel switches
• CPC Class Codes: H04L 7/06 the synchronisation signals differing from the information signals in amplitude, polarity or frequency or length
• CPC Class Codes: H04Q 11/0001 using optical switching
• CPC Class Codes: H04Q 11/0066 Provisions for optical burst or packet networks

Abstract

Currently, with optical time division multiplexing, a switching node is operated at the peak transmission rate. For example, if the data transmission rate is 10 Gbps, the line cards in the switching circuit are also required to operate at this rate despite the fact that the switching node does not actually need to access the data at this rate. Thus, the electronics, which includes the line cards at the switching node, is expensive and less reliable than a low-speed design. In this invention the requirement of operating the switching node electronics at the high speed link bit rate is eliminated by encoding the packet header field at a lower rate than the information in the data field. As a result, the line cards need only operate at the lower header rate. This is possible because the switching node does not need to process the data portion of the packet, but only the header information. The high-speed data portion of the packet is not optically to electrically converted at the switching node, but it passes almost transparently through the switching node. The invention also discloses overlapping several logical networks on the same physical network.

Claims

1. The method of interconnecting at least two logical networks where a first logical network operates at a first bit rate and a second logical network operates at a second bit rate, and each logical network is adapted to receive information via an optical packet having a header field and a data field;

comprising the steps of

connecting the first logical network to an optical fiber for receiving an optical packet, the first logical network being adapted to detect a header field at a third bit rate and a data field at the first bit rate where the first bit rate is greater than the third bit rate,

connecting the second logical network to the optical fiber for receiving an optical packet, the second logical network being adapted to detect a header field at the third bit rate and a data field at the second bit rate where the second bit rate is greater than the third bit rate and is not equal to the first bit rate,

encoding a packet for transmission via the optical fiber to the first and second logical networks with header information at the third bit rate which is detectable by both the first and second logical networks and encoding the packet with data information at either the first or the second bit rate for detection by only one of the first or second logical networks.

2. The method of claim 1 wherein the optical packet has a trailer field further

comprising the steps of

encoding the packet with trailer information at the third bit rate which is detectable by both the first and second logical networks.