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Claims  |
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What is claimed is:
1. A protocol data unit processing device for use in a communication
network to transfer protocol data units within the communication network,
the protocol data unit processing device comprising:
(a) preprocessor means for establishing subsequent processing requirements
of a particular protocol data unit received from the communication network
to generate at least one associated directive for the particular protocol
data unit;
(b) synchronizing means, operatively coupled to the preprocessing means,
for synchronizing the particular protocol data unit with the at least one
associated directive for the particular protocol data unit to generate a
synchronized protocol data unit; and
(c) restructuring means, operatively coupled to the synchronizing means,
for restructuring the synchronized protocol data unit in accordance with
the at least one associated directive for the protocol data unit to
generate a restructured protocol data unit.
2. The protocol data unit processing device of claim 1 wherein the
preprocessor means includes means for establishing subsequent processing
requirements of the particular protocol data unit by identifying,
verifying, and generating at least one associated directive for the
particular protocol data unit.
3. The protocol data unit processing device of claim 1 wherein:
(a) the preprocessor means includes means for operating on a first and a
second protocol data units such that the preprocessor means can interleave
processing of both the first and the second protocol data units during a
single time span; and
(b) the synchronizing means comprises means for synchronizing both the
first and the second protocol data units with the at least one associated
directive for that particular protocol data unit.
4. The protocol data unit processing device of claim 1 wherein the
preprocessor means includes means for establishing the at least one
associated directive for the particular protocol data unit based upon only
a portion of the protocol data unit which enables an identification of the
particular protocol data unit.
5. The protocol data unit processing device of claim 4 wherein the
preprocessor means includes means for sequentially storing the particular
protocol data unit as it is received until the portion of the protocol
data unit which enables the identification of the particular protocol data
unit is received.
6. The protocol data unit processing device of claim 5 wherein:
(a) the preprocessor means includes means for establishing subsequent
processing requirements based upon the stored portion of the particular
protocol data unit; and
(b) the synchronizing means comprises means for storing a portion of the
particular protocol data unit such that the particular protocol data unit
can be synchronized with the at least one associated directive for the
particular protocol data unit.
7. The protocol data unit processing device of claim 4 wherein the
restructuring means operates on the synchronized protocol data unit prior
to the protocol data unit processing device receiving all of the protocol
data unit.
8. The protocol data unit processing device of claim 7 wherein the
restructuring means includes means for outputting a portion of the
restructured protocol data unit to a transmitting device prior to
receiving all of the protocol data unit.
9. The protocol data unit processing device of claim 1 wherein the
restructuring means includes means for restructuring the synchronized
protocol data unit by deleting, inserting, and replacing bits in the
synchronized protocol data unit in accordance with the at least one
associated directive for the protocol data unit.
10. The protocol data unit processing device of claim 1 wherein the
restructuring means includes means for monitoring the synchronized
protocol data unit by dropping, sending, sending a copy of, and auditing
the contents of the synchronized protocol data unit in accordance with the
at least one associated directive for the protocol data unit.
11. The protocol data unit processing device of claim 1 further comprising
receiving means, operatively coupled to the preprocessor means, for
receiving the protocol data unit from the communication network.
12. The protocol data unit processing device of claim 1 further comprising
transmitting means, operatively coupled to the restructuring means, for
transmitting the reconstructed protocol data unit over the communication
network.
13. The protocol data unit processing device of claim 1:
(a) wherein the restructuring means includes means for indicating a
particular transmit path for the restructured protocol data unit; and
(b) further comprising a plurality of transmitting means, operatively
coupled to the restructuring means, for transmitting the restructured
protocol data unit over the communication network via the particular
transmit path indicated by the restructuring means.
14. The protocol data unit processing device of claim 1 wherein:
(a) the protocol data unit processing device is selected from the group
consisting of a bridge, a router, a switch, an inline filter, a protocol
converter, an encapsulating device, and a security device;
(b) the protocol data unit is selected from the group consisting of a
frame, a cell, and a packet;
(c) the communication network is selected from the group consisting of
local area network, wide area network, metropolitan area network, and
wireless network; and
(d) the communication network transfers protocol data units having a
content selected from the group consisting of voice, video, and data.
15. A protocol data unit processing device for use in a communication
network to transfer protocol data units within the communication network,
the protocol data unit processing device comprising:
(a) a first and a second preprocessor, operatively coupled to a receiving
mechanism, for establishing subsequent processing requirements of a
particular received protocol data unit by generating at least one
associated directive for the particular protocol data unit, the first
preprocessor being operatively connected in series to the second
preprocessor such that the first preprocessor performs a portion of
processing necessary for generating the at least one associated directive
and the second preprocessor completes the processing necessary for
generating the at least one associated directive;
(b) synchronizing means, operatively coupled to the preprocessors, for
synchronizing the particular protocol data unit with the at least one
associated directive for the particular protocol data unit to generate a
synchronized protocol data unit;
(c) restructuring means, operatively coupled to the synchronizing means,
for restructuring the synchronized protocol data unit in accordance with
the at least one associated directive for the protocol data unit to
generate a restructured protocol data unit; and
(d) presenting means, operatively coupled to the restructuring means, for
providing the restructured protocol data unit to a transmitting mechanism.
16. The protocol data unit processing device of claim 15 wherein:
(a) the means for optimizing the first preprocessor a identification
process by selectively examining only significant bits of the particular
protocol data unit which affect an identification process and verifying
the identification process by comparing a portion of the particular
protocol data unit with a predetermined tuple; and
(b) the second preprocessor comprises means for generating the at least one
associated directive for the protocol data unit based on the verified
identification process.
17. The protocol data unit processing device of claim 16 wherein the means
for optimizing the first preprocessor comprises means for selectively
examining significant bits of the particular protocol data unit according
to a radix decision process.
18. The protocol data unit processing device of claim 16 wherein the first
preprocessor means for optimizing comprises means for selectively
examining several significant bits of the particular protocol data unit in
a single step of the decision process.
19. The protocol data unit processing device of claim 16 wherein the
predetermined tuple consists of known values for specific portions of the
particular protocol data unit.
20. The protocol data unit processing device of claim 15 wherein:
(a) each preprocessor comprises means for operating on a first and a second
protocol data units such that each preprocessor can interleave processing
of both the first and the second protocol data units during a single time
span; and
(b) the synchronizing means comprises means for synchronizing both the
first and the second protocol data units with the at least one associated
directive for that particular protocol data unit.
21. The protocol data unit processing device of claim 15 wherein the
restructuring means operates on the synchronized protocol data unit prior
to the protocol data unit processing device receiving all of the protocol
data unit.
22. The protocol data unit processing device of claim 15 further comprising
the receiving mechanism, operatively coupled to the first and the second
preprocessor means, which receives the particular protocol data unit from
the communication network, the communication network being selected from
the group consisting of a local protocol data unit source device, a local
area network, a wide area network, a metropolitan area network, and a
wireless network.
23. The protocol data unit processing device of claim 15 further comprising
the transmitting mechanism, operatively coupled to the presenting means,
which transmits the restructured protocol data unit over the communication
network, the communication network being selected from the group
consisting of a local protocol data unit source device, a local area
network, a wide area network, a metropolitan area network, and a wireless
network.
24. A protocol data unit processing device for use in a communication
network to transfer protocol data units within the communication network,
the protocol data unit processing device comprising:
(a) a first and a second preprocessor, operatively coupled to a receiving
mechanism, for establishing subsequent processing requirements of a
particular received protocol data unit by generating at least one
associated directive for the particular protocol data unit, each
preprocessor being optimized to perform the processing necessary for
generating the at least one associated directive for a particular type of
protocol data unit;
(b) synchronizing means, operatively coupled to the preprocessors such that
the first and second preprocessor are connected in parallel, for
synchronizing the particular protocol data unit with the at least one
associated directive for the particular protocol data unit to generate a
synchronized protocol data unit;
(c) restructuring means, operatively coupled to the synchronizing means,
for restructuring the synchronized protocol data unit in accordance with
the at least one associated directive for the protocol data unit to
generate a restructured protocol data unit; and
(d) presenting means, operatively coupled to the restructuring means, for
providing the restructured protocol data unit to a transmitting mechanism.
25. The protocol data unit processing device of claim 24 wherein the first
preprocessor is optimized to perform the processing necessary for
generating the at least one associated directive for a particular type of
protocol data unit selected from the group consisting of a particular
physical layer media type, a particular link layer signaling protocol, and
a particular network layer protocol.
26. The protocol data unit processing device of claim 24 wherein:
(a) each preprocessor comprises means for operating on a first and a second
protocol data units such that each preprocessor can interleave processing
of both the first and the second protocol data units during a single time
span; and
(b) the synchronizing means comprises means for synchronizing both the
first and the second protocol data units with the at least one associated
directive for that particular protocol data unit.
27. The protocol data unit processing device of claim 24 wherein the
restructuring means operates on the synchronized protocol data unit prior
to the protocol data unit processing device receiving all of the protocol
data unit.
28. The protocol data unit processing device of claim 24 further comprising
the receiving mechanism, operatively coupled to the first and the second
preprocessor means, which receives the particular protocol data unit from
the communication network, the communication network being selected from
the group consisting of a local protocol data unit source device, a local
area network, a wide area network, a metropolitan area network, and a
wireless network.
29. The protocol data unit processing device of claim 24 further comprising
the transmitting mechanism, operatively coupled to the presenting means,
which transmits the reconstructed protocol data unit over the
communication network, the communication network being selected from the
group consisting of a local protocol data unit source device, a local area
network, a wide area network, a metropolitan area network, and a wireless
network.
30. A method for utilizing a protocol data unit processing device in a
heterogeneous communication network to transfer protocol data units within
the communication network, the method comprising the steps of:
(a) receiving a first and a second protocol data unit from the
communication network, the first and the second protocol data unit being
of different types;
(b) establishing subsequent processing requirements of the first and the
second protocol data unit to generate at least one associated directive
for each protocol data unit;
(c) synchronizing each protocol data unit with the at least one associated
directive for each protocol data unit to generate a first and a second
synchronized protocol data unit, respectively;
(d) restructuring each synchronized protocol data unit in accordance with
the at least one associated directive for each protocol data unit to
generate a first and a second restructured protocol data unit,
respectively; and
(e) providing the first and the second restructured protocol data unit to
other components in the communication network.
31. The method of claim 30 wherein the first and the second protocol data
unit differ from one another by being selected from the group consisting
of different physical layer media types, different link layer signaling
protocols, and different network layer protocols. |
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Claims |
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Description |
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RELATED INVENTIONS
The present invention is related to:
Co-pending U.S. patent application Ser. No. 08/366,221, filed on Dec. 23,
1994, which is entitled "Method And Apparatus For Accelerated Packet
Forwarding" by Mark Bakke et al.,
Co-pending U.S. patent application Ser. No. 08/366,221, filed on Dec. 23,
1994, which is entitled "Method And Apparatus For Radix Decision Packet
Processing" by Geof Stone,
Co-pending U.S. patent application Ser. No. 08/366,221, filed on Dec. 23,
1994, which is entitled "Method And Apparatus For Virtual Switching" by
Ken Hardwick et al.;
and which were all filed concurrently herewith and assigned to the assignee
of the present invention.
FIELD OF THE INVENTION
The present invention relates generally to data communication networks.
More particularly, the present invention relates to protocol data unit
forwarding systems that direct the flow of protocol data units in the data
communication networks.
BACKGROUND OF THE INVENTION
In a data communication network, a forwarding device (e.g., a data packet
switch) directs protocol data units (e.g., data packets) from one network
node to another. These data packets may include voice, video, or data
information as well as any combination thereof.
To better understand how forwarding devices work within a data
communication network, an analogy may be helpful. In many respects, data
communication networks are similar to postal delivery systems, with pieces
of mail, such as letters or packages, being comparable to the data packets
which are transferred within a data communication network. In a postal
delivery system, the pieces of mail may be input into the postal delivery
system in a variety of ways. Once within the postal delivery system, all
of the pieces of mail are collected and transported to nearby processing
facilities where the pieces of mail are sorted for further processing.
Although each piece of mail will have a unique delivery address, most of
the pieces of mail are automatically sorted by a shorter zip code or some
other type of routing code. Letters without zip codes must be sorted and
processed by hand. Some postal delivery systems also have special forms of
encoded delivery addresses, such as Post Office box numbers at a Post
Office, which are not recognizable by other postal delivery systems such
as Federal Express or United Parcel Service. Regardless of which
particular postal delivery system the piece of mail is deposited into,
once the mail has been sorted by destination it is routed through
additional intermediary processing facilities until it arrives at the
local indicated by the destination on the piece of mail. At this point,
the zip code or routing code is no longer sufficient to deliver the piece
of mail to the intended destination and the local delivery office must
further decode the destination address in order to deliver the piece of
mail to the intended recipient. In addition to processing pieces of mail
for routing the mail to the correct destination, the pieces of mail may go
on through several other processing steps. For example, if the piece of
mail is going out of the country, it must go through a customs operation
in each country. If the national postal delivery system is being used to
deliver the piece of mail then it must also be transferred from one
national postal delivery system to another. In a private postal delivery
system however, this transfer step would not be necessary. The pieces of
mail may also be monitored or filtered for such things as mail fraud
violation or shipment of hazardous materials.
Data packets are manipulated in a data communication network in a manner
similar to that by which pieces of mail are delivered in a postal delivery
system. Data packets, for example, are generated by many different types
of devices and are placed onto a communication network. Typically, the
data packets are concentrated into a forwarding device, such as a local
bridge or router, and are then directed by destination over one or more
media types (e.g., fiber optic) which are connected to destination devices
that could be other larger or smaller bridges or routers. These
destination devices then deliver the data packet to its terminal end point
(i.e., the end user). Along the way the data communication network may
perform filtering and monitoring functions with respect to the data
packets.
Just like postal delivery systems have experienced ever increasing volumes
of mail which must be delivered, the volume of protocol data units being
transferred across computer networks continues to increase as experience
is being gained with this new form of communication delivery system and as
more and more applications, with more and more expansive means are being
developed. In addition, quickly changing technology has made the
underlying data transmission resources for computer communication networks
relatively inexpensive. Fiber optics, for example, offer data transfer
rates in the gigabyte per second range.
The capability or through put of a forwarding device and a computer
communication network can be measured either by the number of data packets
per second or by the number of bits per second which pass through the
forwarding device. The former measure is important because in typical
network traffic, the bulk of protocol data units or data packets are small
and the critical parameter is how many data packets a forwarding device
can handle. If network traffic is weighted by packet size, however, the
bulk of the data is carried in large packets. In large bulk data
transfers, the second measure of how many bits are being transferred is
more important regardless of the number of data packets that are handled.
This tension between packet transfer rate versus bit transfer rate is a
continuing dichotomy in through put measurements of forwarding devices.
Regardless of which through put measure is used, there is a need for
through put rates that are substantially higher than the through put rates
currently available in forwarding devices.
The existing types of forwarding devices which offer the greatest potential
to meet the increasing demand on through put rates are packet switches.
Several classes of packet switches exist. Each class differs substantially
from the other class of devices, but all may be commonly referred to as
packet switches or forwarding devices.
A first class of packet switches is that commonly used in digital telephone
exchanges. By analogy, these switches can perform the functions only of a
mail carrier picking up and delivering mail along a single route. These
switches are intended only to transfer packets among the devices in a
single station, such as a telephone exchange. The format of the packet in
these systems is chosen to make the hardware in the switch as simple as
possible; and this usually means that the packets include fields designed
for direct use by the hardware. The capabilities of this class of switches
(for example, in such areas as congestion control) are very limited in
order to keep the hardware simple.
A second class of packet switches is used in smaller or restricted computer
networks, such as X.25 networks. By analogy, these switches are equivalent
to the Post Office in a single town with no connection to other Post
Offices. In some sense, these switches are little different from the first
class of packet switches described above, but there is one substantial
difference. The format of the packets (that is, the protocols) handled by
the second class of packet switches is much more complex. This greater
complexity is necessary because the protocols are designed to work in less
restricted environments, and because the packet switches must provide a
greater range of services. While the formats interpreted by the first
class of switches are chosen for easy implementation in hardware, the data
packets handled by this second class of switches are generally intended to
be interpreted by software (which can easily and economically handle the
greater complexity) and provides the inherit benefit of incremental
flexibility in the design of the packet switch.
In a third class of packet switches, the packet protocols are intended to
be used in very large data networks having many very dissimilar links
(such as a mix of very high speed local area networks (LANs) and low speed
long distance point to point lines). Examples of such protocols are the
United States designed Transmission Control Protocol/Internetwork Program
(TCP/IP), and the International Standards Organization's Internetworking
Protocol/Connectionless Network Service (IP/CLNS) protocols.
In addition, this third class of switches (commonly referred to as
bridge/routers) often must handle multiple protocols simultaneously. This
third class of switches is very similar to the mail processing devices
used in the modern postal system. Just as there are many countries, there
are many data packet protocols used in computer networks. While a single
postal system was once thought to be sufficient to handle mail going
anywhere in the world, today several competing systems like United Parcel
Service, Federal Express, and the U.S. Postal Service exist to handle the
special needs of mail going to every country, state, city, town, and
street in the world. Similarly, in computer communication systems, the
packet switches are more involved in the carrying of data, and must
understand some of the details of each protocol to be able to correctly
handle data packets which are being conveyed in that protocol. The routers
in this third class of packet switches often have to make fairly complex
changes to the data packets as they pass through the packet switch.
It is this latter class of packet switches to which the following detailed
description primarily relates. It will be appreciated however, that the
detailed description of this invention can readily be applied to the first
and second class of switches as well. In current conventional packet
switch design, a programmed general purpose processor examines each data
packet as it arrives over the network interface and then processes that
packet. Packet processing requires assignment of the data packet to an
outbound network interface for transmission over the next communications
link in the data path. While attempts are being made to build higher speed
packet switches, based on this architecture of using general purpose
processors, the attempts have not been very successful. One approach is to
use faster processors, another is to make the software run faster, and a
third is to apply multiple processors to the processing task. All of these
approaches fail to meet the increasing performance demands for packet
switches for the reasons noted below.
The approach which uses faster processors simply keeps pace with processor
dependent (future) demands because the traffic which the packet switch
will handle will depend upon the speed of the user processors being used
to generate the traffic. Those user processors, like the processors in the
packet switches, will increase in speed at more or less the same rate.
Accordingly, there is no overall increase in the ability of the future
packet switch over present packet switches, relative to traffic load.
Furthermore, this approach may be impractical as not being cost-effective
for widespread use. For example, two high speed machines, distant from
each other, must have intermediate switches which are all equally as
powerful; deployment on a large scale of such expensive switches is not
likely to be practicable.
The approach which increases the execution rate of the software itself by,
for example, removing excess instructions or writing the code in assembly
language, leads to a limit beyond which an increase in performance cannot
be made. The gains which result are typically small (a few percent) and
the engineering costs of such distortions in the software are significant
in the long term. This type of assembly code optimization restricts the
ability to enhance the software as well as port the software to a
different processor platform.
The use of multiple processors to avoid the "processor bottleneck" provides
some gains but again has limits. Given a code path to forward a data
packet, it is not plausible to split that path into more than a few
stages. Typically these stages would involve network input, protocol
functions, and network output. The basis for this limitation is the
overhead incurred to interface the different processors beyond a limited
number of task divisions. That is, after a certain point, the increase in
interface overhead outweighs the savings obtained from the additional
stage. This is particularly true because of the need to tightly integrate
the various components; for example, congestion control at the protocol
level requires dose coordination with the output device. Also, the
interface overhead costs are made more severe by the complication of the
interface which is required.
Currently, most bridge/router implementations rely heavily on off-the-shelf
microprocessors to perform the packet forwarding functions. The best
implementations are able to sustain processing rates approaching 100,000
packets per second (PPS). When dealing with media such as ethernet or
current telecommunications lines, this processing rate is more than
adequate. When faster media such as Fiber Distributed Data Interchange
(FDDI) is used, existing processing rates may still be sufficient as long
as there is only one such high packet rate interface present. When
multiple high packet rate interfaces are used, 100,000 PPS become
inadequate. Current software-based implementations for bridges/routers are
simply not capable of media-rate packet forwarding on emerging media such
as asynchronous transfer mode (ATM) or Optical Connection-12 Synchronous
Optical Network (OC-12 SONET) which can accommodate communication rates up
to 6 times the current 100 megabits per second limits to rates of 600
megabits per second.
It should be noted that the ever increasing power of off-the-shelf
microprocessors might solve the throughput problem, but this is probably a
vain hope. For example a single OC-24 ATM interface can sustain nearly 3
million internetworking protocol (IP) packets per second. This is over 30
times the rates achieved by the current best software techniques. If
processing power doubles every year, the wait for sufficient processing
power to make a software approach viable would be at least 4-5 years. In
addition, the media capabilities will likely continue to increase over
such a span of years. Additionally, any such processor will likely require
large amounts of the fastest (most expensive) memory available to operate
at full speed, resulting in an unacceptably high system cost.
In general then, the multiprocessor approach is not the answer to
substantially increasing the throughput of the packet switching network.
This has been borne out by several attempts by technically well-regarded
groups to build packet switches using this approach. While aggregate
throughput over a large number of interfaces can be obtained, this is, in
reality, little different than having a large number of small switches. It
has thus far proven implausible to substantially speed up a single stream
using the multiprocessing approach.
A need still exists for an improved protocol data unit (i.e., frame, cell,
or packet) forwarding system which solves the above-identified problems in
a manner which can better handle large numbers of input streams, large
numbers of output destinations and lines, many different types of
communication protocols, and large and small data packets at both high bit
throughput rates and high packet throughput rates, while maintaining
reasonable costs and complexity.
SUMMARY OF THE INVENTION
The present invention provides a packet processing system with improved
throughput performance by means of a method and apparatus for accelerated
processing of protocol data units. The present invention addresses the
problem of media rate forwarding of packets at gigabyte rates by providing
an architecture for the design of bridges/routers that are capable of
forwarding packets across different media which can sustain multi-gigabyte
rates. This architecture also includes design approaches for implementing
key features of a packet-forwarding device operating at these high
transfer rates, such as filtering functions. By splitting processing
functions, the present invention avoids the "processor bottleneck"
inherent in prior art processing device architectures.
In accordance with a first aspect of the invention, a protocol data unit
processor is used in a communication network to transfer protocol data
units within the communication network. The processor includes a
preprocessor which establishes subsequent processing requirements of a
particular protocol data unit received from the communication network to
generate at least one associated directive for the particular protocol
data unit. Subsequently, a synchronizing mechanism synchronizes the
particular protocol data unit with the at least one associated directive
to generate a synchronized protocol data unit. A restructuring device
restructures the synchronized protocol data unit in accordance with the at
least one associated directive for the protocol data unit to generate a
restructured protocol data unit. In addition, a method of operating the
protocol data unit processor in a heterogeneous communication network is
provided.
With reference to the postal delivery analogy, the present invention can be
likened to a system which both increases the speed at which pieces of mail
can be moved through the postal delivery system and provides an ability to
handle in a common system pieces of mail entered into a variety of
different postal delivery systems. By utilizing the preprocessor and
restructuring device of the present invention to split the required
protocol data unit processing functions, the present invention is able to
significantly increase the through put of the processing device, both in
terms of the number of data packets per second and in terms of the number
of bits per second which pass through the processing device.
The preprocessor preferably establishes the subsequent processing
requirements of the particular protocol data unit by identifying,
verifying, and generating at least one associated directive for the
particular protocol data unit. In addition, the restructuring device
preferably restructures the synchronized protocol data unit by deleting,
inserting, and replacing bits in the synchronized protocol data unit in
accordance with the at least one associated directive for the protocol
data unit. Alternatively, the restructuring device may, in addition to or
in place of modifying particular bits, monitor the synchronized protocol
data unit by dropping, sending, sending a copy of, and/or auditing the
contents of the synchronized protocol data unit in accordance with the at
least one associated directives for the protocol data unit.
In order to accelerate the processing of a received protocol data unit, the
preprocessor preferably is configured to operate on a first and a second
protocol data unit such that the preprocessor can interleave processing of
both the first and the second protocol data unit during a single time
span. In addition, multiple preprocessors connected in either parallel or
series may be used to increase the through put of protocol data units.
This use of multiple preprocessors may necessitate the use of a more
sophisticated synchronizing mechanism which is able to track and
synchronize more that one protocol data unit at a time with the particular
associated directives for each protocol data unit. In addition, the
preprocessor is configured to establish the at least one associated
directive for the particular protocol data unit after having received only
a portion (i.e., the first several bits or bytes) of the protocol data
unit. The preprocessor may need to buffer into memory or store a portion
of the particular protocol data unit as it is received until a large
enough portion or the particular portion of the protocol data unit which
enables the identification of the particular protocol data unit is
received. Similarly, the restructuring device preferably is configured to
operate on the synchronized protocol data unit prior to the protocol data
unit processing device receiving all of the protocol data unit. This
optimization can be taken a step further by outputting a portion of the
restructured protocol data unit to a transmitting device prior to
receiving all of the protocol data unit. All of these optimizations are
particularly important when manipulating large protocol data units which
extend over several frames or consist of several smaller parts that are
received at various times and/or from various incoming interfaces.
In accordance with a second aspect of the invention, a method of operating
a protocol data unit processing device in a heterogeneous communication
network is provided to transfer protocol data units within the
communication network. This method is performed by device-implemented
steps in a series of distinct processing steps that can be implemented in
one or more processors. In the first processing step a first and a second
protocol data unit are received from the communication network where the
first and the second protocol data unit are of different types. The second
processing step involves establishing the subsequent processing
requirements of the first and the second protocol data unit to generate at
least one associated directive for each protocol data unit. Each protocol
data unit is synchronized with the at least one associated directive for
each protocol data unit to generate a first and a second synchronized
protocol data unit, respectively. Then, each synchronized protocol data
unit is restructured in accordance with the at least one associated
directive for each protocol data unit to generate a first and a second
restructured protocol data unit, respectively. Finally, the first and the
second restructured protocol data unit are provided to other components in
the communication network.
The first and the second protocol data unit may differ from one another in
several ways in the heterogeneous communication network including but not
limited to being of different physical layer media types, different link
layer signaling protocols, and/or different network layer protocols.
These and various other features as well as advantages which characterize
the present invention will be apparent upon reading of the following
detailed description and review of the associated drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a prior art network device.
FIG. 2 is a block diagram of a preferred embodiment network device in
accordance with the present invention.
FIG. 3 is a block diagram of an alternative preferred embodiment network
device having serial connected preprocessors in accordance with the
present invention.
FIG. 4 is a block diagram of an alternative preferred embodiment network
device having parallel connected preprocessors in accordance with the
present invention.
FIG. 5 is a block diagram of a preferred embodiment decision processor and
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