CA2298732A1

CA2298732A1 - 10 gigabit ethernet mappings for a common lan/wan pmd interface and simple universal pmd interface

Info

Publication number: CA2298732A1
Application number: CA 2298732
Authority: CA
Inventors: Paul A. Bottorff; Norival R. Figueira; David W. Martin; Timothy J. Armstrong; Bijan Raahemi
Original assignee: Nortel Networks Corp
Current assignee: Nortel Networks Corp
Priority date: 1999-06-01
Filing date: 2000-02-09
Publication date: 2000-12-01

Abstract

Apparatus and methods enabling High Speed (HS) transport of Ethernet data frames via a Unified Dual-Scrambler physical interface is described. The physical interface is adapted to convey Media Access Control (MAC) layer data in a Local Area Network (LAN) on Metropolitan Area Network (MAN) configuration at 10.000 Gb/s and further adapted to convey MAC layer data in a Wide Area Network (WAN) configuration at 9.58464 Gb/s. Physical layer data transport is provided over a Synchronous Optics NETwork (SONET) / Synchronous Digital Hierarchy (SDH) concatenated OC-192 links at a 9.95328 Gb/s signal rate in selectable frame formats selected from a LAN/MAN data transport frame format and a WAN data transport frame format. The use of the LAN/MAN data transport format and the WAN data transport format on the Unified Dual-Scrambler) physical layer interface is enabled via a Simple Universal Physical Medium Dependent (PMD) Interface (SUPI).

Description

1114UHU / 1~141HU y-1.3~Gtf~lUU(:, GIGABIT ETHERNET MAPPINGS FOR A COMMON
LAN/WAN PMD INTERFACE WITH A STMPLE UNIVERSAL
PHYSICAL MEDIUM DEPENDENT INTERFACE
CR088-REF~RENCL TO RELATED APPhIClITI0~8 5 This application is related to, and claims priorit of the Applicant s co-pending Canadian Patent P~plicatio serial number 2,273,522 filed June 18t, 1999 entitled ~HIG
SPEED ETHERNET BASED ON SONET TECHNOLOGY", the subjec matter of which is incorporated herein by reference.
10 T~ICIIL 8I8LD
The present invention relates to high speed dat transport over Local Area Networks (LANs), Metropolita Area Networks (MANS) and Wide Area Networks (WANs) and, i particular to High Speed (HS) transport of Ethernet frame using Synchronous Optical NETwork (SONET) / Synchronou Digital Hierarchy (SDH) technology at the PHYsical lin layer (PHY).
HJLCaCOR00~1D O! THE INV31~TION
For the last decades, the industry has evolved fro voice circuit switching to data message switching, then t data oriented packet switching. In the past years, othe technologies have been introduced into the marketplace t enhance or supplant these older technologies, such as fram relay, fast Ethernet, switched Ethernet, and ATM. Yet eve some of these technologies do not solve the curren problems; frame relay is fundamentally used for wide are.
network (WAN) technology and fast Ethernet and switche~
Ethernet are for local area network (LAN) technologies.

1214080 / 1.21.4180 9-135213-lU

In 1984 CCITT adopted the first T-serie Aecommendations which was a milestone in the development o Integrated Services Digital Networks (ISDN). Thes Recommendations are concerned with services network-network interfaces (NNIy, user-network interface (UNIy and overall network aspects.
Open System Interconnection (OSI) is a referenc model defining a seven-layer framework of protocols fo data communications, designed with the purpose to allow an computer anywhere in the world to communicate with an other, as long as they obey the OSI standards. Layerin divides the total communications problem into smalle functions, while ensuring independence of each layer fro:
the next layer, by defining services provided by a layer t 1S the next layer, independent of how these services ar performed.
The lowest first layer is the PHYsical layer (PHY) covering the physical interfaces between the devices, an is concerned with transmitting raw bits over communicatio channels, and informing second layer (Data Link) of loss o connectivity. Physical layer functions are for example t add, drop and multiplex traffic. An add/drop multiplexe (ADM) unit can multiplex/demultiplex any of tributar inputs provided with into/from a signal. An AD1K can b used as a hub, a roister, or a terminal. vOhen used as roister, it only accesses signals that need to be dropped o added at that site, the rest of the traffic passes straigh through.
An important task of the data link layer (secon layer) is to break data into frames, to then transmit thes frames (sequentially) and, in some cases, to proces acknowledgement frames sent back .by a receiver. Th _ 3 _ network layer (the third layer) provides the functional an procedural means to set-up and terminate a connection, t route data and to control the data flow across the network The remaining layers are application oriented, bein concerned with providing various service functions t applications/users, such as session control, networ management, and other services.
Some technologies are more appropriately applied a certain layers. For example, SONET~ is a physical lave technology and is used as a transport service for ATM
S1~S, frame relay, T1, E1, etc, while ATM is transports over SONET, copper, twisted pairs, FDDI as physical layers having the data layer subdivided into an ATM layer and a:
ATM adaptation layer.
Local area networks (LANs) connect computers to on another. Hoth general pu~c~pose computers refered to a hosts or clients, and special purpose computers refered t as servers, provide communal files, e-mail, etc.
The oldest and most widely deployed LAN da transport complies with the Ethernet staz~dard. Ethern data transport in many cases is provided over a Fib Distributed Data Interface (FDDI) physical layer, and Media Access Control (MAC) data layer.
The IEEE became involved standardizing LAN dat transport under the 802 committee. The Etherne specification was published as the IEEE 802.3 standar designed for data applications and is based on a shared bu architecture in which all network nodes share the sam medium.

A Wide Area Network (WAN) is a packet switche public data network that connects various packet switchin nodes and transmission facilities to customer premise equipment (computer stations). A WAN differs from the LA
in geographic coverage and data transmission rates, an generally also in the data transmission technology used.
The Metropolitan Area Network (MAN) technolo differs from the LAN and WAN in geographic coverage a data transmission rates. A MAN could be owned by organization, or could be public, and enables users share efficiently widely distributed resources. A M
could also serve as a backbone for a network configured interconnect distributed LANs. Recently, the M
technologies have been evolves towards WAN technologies the backbone provision, due to the increased demand in da communication.
Recently it has become evident that LAN shared bu architecture is insufficient to meet the demands o applications that require a large bandwidth, and that LAN
are beginning to become the bottleneck in data trasport For this reason, the separation of data into cells i deferred until within the network, but the higher leve information is carried to the end station.
Switched Ethernet technology: was developed t provide more capacity to an end-user, does not rely on shared medium providing point-to-point data transpor between a network node and an Ethernet switch. Therefor instead of sharing a 10 Mbit/s medium, the network node ha access to a dedicated lOMbits/s feed. A switched Etherne network is more flexible, in that it may include nodes tha use a port. at a given full rate, nodes that share a port or nodes that have access to more than one port.

However, switched Ethernet provides only limite bandwidth and supports data traffic only. As Ethernet hub and switches are growing in use, they have become a inexpensive means to provide more bandwidth t workstations. A more efficient solution for bursty traffi is needed.
Nonetheless, of great concern for network provider is LAN performance at high speeds. A IOGb/s market i emerging fast in campus backbone networks.
In addition, several existing problems cannot k solved by the current solutions. For example, the LF
bandwidth is currently provisioned in a rigid manner, whit many users need application dependent scaleable bandwidth.
It would be highly beneficial to have a unif 1S architecture for LANs, MANS and WANs, by seamles bridging the LAN technology onto MAN and WAN through same frame protocol/format and transmission technology.
The dominant signal format in the fiber opti networks follows the synchronous standard SONET in Nort America and SDH elsewhere. In this specification, SONET i defined to include SDH. SONET enables the multiplexing adding and dropping and general transmission of signal through links..
It is a valuable attribute for a service to b adapted for transport over a SONET network. The networ provider can make use of the large base of installs SONET-compatible equipment. As well, SONET provides th ability to combine and consolidate traffic from differen locations through one facility (grooming), and reduces th amount of back-to-back multiplexing. More importantly network providers can reduce the operation cost of thei transmission network by using the operation administration, maintenance arid provisioning (OAM&P
features of SONET.
Mapping of one rate or format into another is wel known. Hellcore GR-232 describes in detail the standar mapping of the common asynchronous transmission format (DSO, DS1, DS2, DS3, etc) onto SONET. Similar mappings ar defined for the ETSI hierarchy mapping into $DH. Optics transmission equipment designed for mapping one proprietar format into another is also available on the market, e.g Nortel's FD-565 could carry the FD-135 proprietary forma as well as the DS3 standard format.
As a physical carrier technology and also due t the advantages listed above, SONET looks as a candidate o choice for carrying Ethernet.
Applicant's co-pending Canadian Patent Applicati serial number 2,273,522 proposes means for achievi efficient HS Ethernet frame mapping into a SONET contain at a data transport rate of 9.58464Gb/s for LAN/MAN/OV
configurations to take advantage of the SONET features a of the installed base of SONET equipment.
Cisco Systems also has made a proposal seekin standardization claiming data throughput rates of 10 Gb/
for LAN configurations and 9.29419 Gb/s fox WA
configurations.
There remains a need for further improvement efficiently mapping HS Ethernet frames into SONET fre such that the data stream can be added and drox _ 7 efficiently with low risk (high reliability) a comparatively inexpensive hardware.
801~1RY 08 T8B INV~IZ'I011T
The present invention broadens the scope of th lOGE SONET-based system described in Applicant's co-pendin Canadian Patent Application serial number 2,273,522, b providing a lOGE LAN application, in addition to th previous LOGE WAN application. The present inventio provides a lOGB mapping with a common physical medi dependent (PMD) interface, specifically a common framin format and line rate, for both LAN and tnTAN PHY application Thus an aspect of the present invention provides common PMD interface to compass 10GE PHY LAN and WA
application using inter-frame gap (IFG) compression t reduce the 20.0 Gb/a data rate from the MAN, in combinatio with a SONET frame stripped of all overhead (OH) bytes except for a subset of the Al and A2 framing bytes. I
this way the data from the 10.0 Gb/s MAC can be containe in a line rata signal of 9.953280 Gb/s.
An advantage of the present invention is that, defining a unified LOGE mapping for both the LAN and PHYs, the installed base and future networks of OC-192 seamlessly carry lOGE.
The present invention further defines a 4x ~2.5Gb/
2S physical interface for use between transmission component operating at a serial rate of ~lOGb/s. Each of the fou lanes (e. g. WDM channels or fibers) carries a scramble signal divided from the original ~10 Gb/s signal.
By operating at ~2.5 Gb/s, the system of present invention uses lower risk (i.e. more robust 1214080 / 1214180 9-13528-lU0 _ g _ reliable) technology than previous proposals in whic payload data is encoded at a higher signal rate to achiev the same data throughput. By operating at this rate, wit is a factor of -4x some other proposals, 'Sb fewer signa pins and traces are required. The present inventio provides an optimum solution for minimizing interfac complexity, while operating at the maximum rate technicall achievable with minimal risk.
An advantage of the present invention is that b using a scrambled encode, the data rate and signal rate ax identical. This achieves optimum transmission efficiency without increasing the signal rate (and therefore risk).
BRIEF' DESCRIPTION 08 T98 DR11~9iT,~Nf3S
Further features and advantages of the prese invention will become apparent from the following detail description, taken in combination with the append drawings, in which:
Fig. 1.
It will be noted that throughout the appe drawings, like features are identified by like refer numerals.
DS't'7lITrSD D8~8CRIFTI08 08 TI3E PREI~RRED $EHODI

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a 1214080 / 1214180 Z ~ 9-13528-10 The embodiments) of the invention described a is (are) intended to be exemplary or~.ly. The scope of invention is therefore intended to be limited solely by scope of the appended claims.

Claims

I/WE CLAIM:

1. A method of add high speed Ethernet frames onto one of a SONET OC-192 and a SDH VC-4-64 concatenated signals, the method comprising the steps of:
a) providing a SONET frame stripped of at least a portion of a frame overhead;
b) compressing an inter-frame gap between frames of a MAC signal; and c) mapping the compressed MAC signal onto the stripped SONET frame.