Multicast data distribution system

Details Multicast data distribution system Multicast data distribution system

2000-03-24

2002-06-18

Chin, Wellington (Department: 2664)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S432000, C714S011000

Reexamination Certificate

active

06408000

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to systems for automatically electronically distributing information. In particular, the invention is described with respect to a system for distributing securities market information using electronic transmission.
Securities Industry Automation Corporation (SIAC), the assignee of this application, collects and distributes trade and quote data for the U.S. stock and options markets. The data has been distributed using the system depicted in FIG.
1
and is also described in an article entitled “Wall Street Takes Stock of IP Multicast” by A. Francis Bach published in BUSINESS COMMUNICATIONS REVIEW, January, 1998.
As depicted in
FIG. 1
the current system includes two sites from which data is transmitted to provide redundancy and resistance to system failure. One site, “site B”, is located at SIAC's facility in Brooklyn, N.Y. The other site, “site A”, is located at 55 Water Street, New York, N.Y. Site A includes Option Price Reporting Authority (OPRA) system
12
, which is a tandem computer which is operated by SIAC to gather and distribute option trade and quote information from all U.S. option exchanges on behalf of the Options Price Reporting Authority consortium. A similar system
16
is provided at site B. Systems
12
and
16
provide redundant capabilities so that if there is a failure of system
12
, the tasks normally performed by system
12
will be performed by system
16
, and vice versa. In addition to option price reporting, SIAC provides reporting of the stock trading activities on behalf of the Consolidated Tape Association consortium, including a Consolidated Tape System (CTS) which reports trades and a Consolidated Quote System (CQS) which reports quotations. These systems collect, integrate and distribute listed securities' trade and quote data from the New York Stock Exchange (NYSE), the American Stock Exchange (AMEX), the National Association of Securities Dealers (NASDAQ) and the regional exchanges. Systems
14
and
18
normally provide the CQS service and the CTS service, respectively, but each system has have the capability to assume operations on behalf of the other system in the event of a system failure.
In addition to the redundancy of computers
12
,
14
,
16
,
18
, there is provided further redundancy in connection with the distribution of information to the users. In particular each of computers
12
,
14
,
16
and
18
includes a primary network interface (P) and a backup network interface (B). Each interface is connected to a multicast packet replicator
20
which provides duplicated packet outputs to a local area network through source router
22
. One packet is supplied to a distribution router
24
A at site A, and the other packet is provided to another distribution packet router
24
B at site B via the local area network. Communication of the replicated packets between the sites are provided using an optical cable system.
Distribution routers
24
A and
24
B at each of the sites distribute identical packet streams called stream A and stream B to users
26
to provide for redundancy in the event of a communications or equipment failure. Further redundancies are built into the system. For example, in the event of a failure in one of the multicast packet replicators
20
or source routers
22
, the data stream from any of the systems
12
,
14
,
16
and
18
can be sent through the backup connection to another multicast packet replica
20
and to an alternate source router. While systems
12
and
16
each have a primary and a backup network port, systems
14
and
18
have a primary, a backup and foldover network ports. In the event of a failure, for example, of system
16
the tasks undertaken by that system would be folded over to system
12
and transmitted using the primary network port of system
12
along with the data normally generated by system
12
. The backup ports on systems
12
and
16
are used in the event of a failure of the primary port. In the event of a system failure of system
18
, the functions of system
18
would be taken up by system
14
and the data generated would be provided to the network foldover port provided on computer
14
while the primary function and backup ports of computer
14
would continue to provide their normal primary function and provide the backup function for both the primary and foldover network ports. The system as illustrated includes two source routers at each site for providing further redundancy in routing the data stream distributed by each site.
In some instances where subscribers to a data service receive the redundant stream A and stream B data through different receiving ports in a user network, an anomalous behavior can occur which prevents the systems from simultaneously receiving the redundant data streams. Referring to
FIG. 2
there is shown a data network of user
26
having two network ports
32
and
36
respectively receiving data stream
30
from site A and data stream
34
from site B. Network ports
32
and
36
, are preferably located at Sites A and B respectively. Receiving ports
32
and
36
of system
26
interact with distribution routers
24
A and
24
B following a Distance Vector Multicast Routing Protocol (DVRP), which in some cases controls the receiving ports
32
and
36
to only receive data stream
30
via receiving port
32
. It is an object of the present invention to eliminate such anomalous behavior and provide a system which transmits two data steams, both of which can be received by a user network using the DVMRP protocol
SUMMARY OF THE INVENTION
According to the invention there is provided an improvement in a system for electronically distributing data via first and second redundant data distribution facilities, wherein replicating apparatus receives original data packets and provides output first and second data packets for distribution through the first and second data distribution facilities. According to the invention, the replicating apparatus provides the first and second data packets via first and second network interfaces, such that the first and second data packets have different source address data corresponding to the first and second network interfaces.
In a preferred arrangement the first and second data packets are provided via first and second source routers coupled to the first and second network interfaces.
For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description, taken in conjunction with the accompanying drawings, and its scope will be pointed out in the appended claims.


REFERENCES:
patent: 5436886 (1995-07-01), McGill
patent: 5926463 (1999-07-01), Ahearn et al.
patent: 6201808 (2001-03-01), Wang et al.
Aggarwal et al, “Dualcast: A Scheme for Reliable Multicasting”, Network Protocols, 1994, pp. 15-22.*
“Wall Street Takes Stock of IP Multicast”, A. Francis Bach, Business Communications Review, Jan. 1998, pp. 48-52.
“The Use of IP Multicasting to Disseminate Market Data Information”, A. Francis Bach, WSTA Ticker, Sep./Oct. 1997.

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