Multiplex communications – Pathfinding or routing
Reexamination Certificate
1998-05-01
2001-08-28
Harrison, Jessica J. (Department: 3713)
Multiplex communications
Pathfinding or routing
C370S360000
Reexamination Certificate
active
06282188
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electronic network switching device, and more particularly to a hub device used in a network loop architecture and which includes a plurality of interconnected internal hubs which may operate in conjunction to form a unified loop or subsets of the available interconnections.
BACKGROUND INFORMATION
Electronic data systems are frequently interconnected using network communication Systems. Area-wide networks and channels are two approaches that have been developed for computer network architectures. Traditional networks (e.g., LAN's and WAN's) offer a great deal of flexibility and relatively large distance capabilities. Channels, such as the Enterprise System Connection (ESCON) and the Small Computer System Interface (SCSI), have been developed for high performance and reliability. Channels typically use dedicated short-distance connections between computers or between computers and peripherals.
Features of both channels and networks have been incorporated into a new network standard known as “Fibre Channel”. Fibre Channel systems combine the speed and reliability of channels with the flexibility and connectivity of networks. Fibre Channel products currently can run at very high data rates, such as 266 Mbps or 1062 Mbps. These speeds are sufficient to handle quite demanding applications, such as uncompressed, full motion, high-quality video. ANSI specifications, such as X3.230-1994, define the Fibre Channel network. This specification distributes Fibre Channel functions among five layers. The five functional layers of the Fibre Channel are: FC-
0
—the physical media layer; FC-
1
—the coding and encoding layer; FC-
2
—the actual transport mechanism, including the framing protocol and flow control between nodes; FC-
3
—the common services layer; and FC-
4
—the upper layer protocol.
There are generally three ways to deploy a Fibre Channel network: simple point-to-point connections; arbitrated loops; and switched fabrics. The simplest topology is the point-to-point configuration, which simply connects any two Fibre Channel systems directly. Arbitrated loops are Fibre Channel ring connections that provide shared access to bandwidth via arbitration. Switched Fibre Channel networks, called “fabrics”, are a form of cross-point switching.
Conventional Fibre Channel Arbitrated Loop (“FC-AL”) protocols provide for loop functionality in the interconnection of devices or loop segments through node ports. However, direct interconnection of node ports is problematic in that a failure at one node port in a loop typically causes the failure of the entire loop. This difficulty is overcome in conventional Fibre Channel technology through the use of hubs. Hubs include a number of hub ports interconnected in a loop topology. Node ports are connected to hub ports, forming a star topology with the hub at the center. Hub ports which are not connected to node ports or which are connected to failed node ports are bypassed. In this way, the loop is maintained despite removal or failure of node ports.
FIG. 1A
illustrates two conventional hubs with attached node ports, where a node port represents a connection to a single operational device or may represent a loop segment of a series of devices directly interconnected. Each node port typically has two data channels, one data channel carrying data from the hub port to the node port, and one data channel carrying data from the node port to the hub port.
In
FIG. 1A
, hub
100
has four hub ports
102
,
104
,
106
,
108
(the number of hub ports shown in the hubs of figures herein is for illustrative purposes only and is not a limitation on the operation or construction of hubs according to embodiments within the scope of the present invention). Hub ports
102
-
108
of hub
100
are interconnected by a series of internal hub links
110
,
112
,
114
,
116
. In this way, hub ports
102
-
108
are connected in a loop topology by internal hub links
110
-
116
. The data path of the loop flows: from hub port
102
through internal hub link
110
to hub port
104
; out to node port
124
and back to hub port
104
; through internal hub link
112
to hub port
106
; through internal hub link
114
to hub port
108
; through internal hub link
116
to hub port
102
; out to node port
118
and back to hub port
102
, completing the loop.
Node ports are attached to hub
100
in a physical star topology. However, the internal loop topology of hub
100
provided by the interconnection of hub ports
102
-
108
provides an effective loop topology for node ports attached tb hub
100
. A node port
118
is attached to hub
100
at hub port
102
. A data channel
120
carries data from node port
118
to hub port
102
. A data channel
122
carries data from hub port
102
to node port
118
. These data channels
120
,
122
create the connection between node port
118
and the loop internal to hub
100
. A second node port
124
is also attached to hub
100
at hub port
104
with data channels in the same way.
FIG. 1A
also shows a second hub
150
. Hub
150
, similar to hub
100
, contains four hub ports
152
,
154
,
156
,
158
which are interconnected by internal hub links
160
,
162
,
164
,
166
in a loop topology. Two node ports
168
,
170
are attached to hub
150
at hub ports
152
and
156
, respectively, with pairs of data channels. As shown in
FIG. 1A
, hub
100
and hub
150
form two independent loops. Thus, node port
118
and node port
124
can communicate, node port
168
and port
170
can communicate, but node port
118
has no connection to node ports
168
or
170
.
A conventional technique for joining the loops contained within hub
100
and hub
150
is illustrated in FIG.
1
B. As described above, each hub port of a hub has two data channels which are available to connect the hub port to a node port (recall in
FIG. 1A
, data channel
120
carries data from node port
118
to hub port
102
and data channel
122
carries data from hub port
102
to node port
118
). In
FIG. 1B
, the connection of hub
100
to hub
150
is accomplished by linking data channels of two hub ports, one hub port from each hub. In
FIG. 1B
, two data channels
172
,
174
connect hub port
106
of hub port
100
to hub port
164
of hub
150
. Data channel
172
carries data channel from hub port
106
to hub port
154
. Data channel
174
carries data from hub port
154
to hub port
106
. Data channels
172
,
174
perform a similar function to internal hub links
110
-
116
,
160
-
166
, carrying data from one hub port to the next hub port in the loop. This interconnection between hub ports
106
and
154
connects the loops contained within hubs
100
and
150
.
The datapath throughout the linked loop topology follows a circular pattern of hub ports and no deports:
102
,
104
,
124
,
104
,
106
,
154
,
156
,
170
,
156
,
158
,
152
,
168
,
152
,
154
,
106
,
108
,
102
,
118
,
102
. In this sense, hub ports
106
and
154
act as a common juncture between the two loops defined by hubs
100
and
150
. In contrast to the configuration in
FIG. 1A
, in
FIG. 1B
node port
118
can communicate with any of the other node ports in the expanded loop: node port
124
, node port
168
and node port
170
.
A problem with the technique illustrated in
FIG. 1B
is that each hub must dedicate at least one hub port to the linking operations and connections between hubs. In this event, the logic and circuitry internal to a hub port, which is designed to interact with a node port or loop segment, is rendered idle and wasted.
In addition, the connection and disconnection of hubs, which are connected as illustrated in
FIG. 1B
, is sometimes a logistically complicated physical process involving the actual movement of cable or devices. Another problematic aspect of the hub port to hub port connection illustrated in
FIG. 1B
is that such a connection process is only useful to join separate hubs. It may be desirable to divide a hub into smaller pieces in order to increase the granularity of the loop
Brewer David
Hashemi Hossein
Henson Karl M.
Emulex Corporation
Fish & Richardson P.C.
Harrison Jessica J.
Nguyen Kim T.
LandOfFree
Scalable hub does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Scalable hub, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Scalable hub will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2452894