Note: Descriptions are shown in the official language in which they were submitted.
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OFFERING DIFFERENTIATED SERVICES
BACKGROUND
This invention relates to offering differentiated
services.
A differentiated services architecture is a rule-based
mechanism that allows for differentiation of network services
based on performance. Different types of network traffic can
be identified, e.g., in a packet header, for different types
of forwarding or routing across the network. Using the
identification and network policies, network resources can be
reserved to forward or route the network traffic across the
network.
SUMMARY
According to an aspect of the present invention,
differentiated services are offered across multiple virtual
circuits running between the same destinations and different
service quality attributes are associated with the multiple
virtual circuits.
According t~ another aspect of the present invention,
quality characteristics of multiple virtual circuits running
across a network between the same destinations are signaled to
a destination having traffic to 'send across the network and it
is determined which virtual circuit to shunt the traffic t-o
based at least in part on service characteristics of the
virtual circuits and on service needs of the traffic.
According to another aspect of the present invention, a
process is associated with a destination and is configured to
determine which of multiple virtual circuits to send traffic
over based at least in part on service characteristics of the
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traffic and on the service characteristics of the multiple
virtual circuits.
One or more of the following advantages may be provided
by one or more aspects of the invention. Offering
differentiated services over a frame relay network having a
plurality of virtual circuits minimizes the burden of
configuration. Having multiple virtual circuits between
destinations allows traffic between two (or more) points to
receive different treatment and differentiated service; the
traffic is sent on a virtual circuit that can optimize the QoS
(quality of service) parameters of the traffic. Deciding
which virtual circuit to send traffic over before the traffic
reaches the network and/or the virtual circuits prevents the
network from being unable to classify the traffic because the
traffic's classification information was compressed before the
traffic reached the network or from having to decompress the
traffic, classify it, and recompress it.
DESCRIPTION OF DRAWINGS.
FIG. 1 is a diagram of a network configuration.
FIG. 2 is a flowchart showing a process of offering
differentiated services over a frame relay network in
accordance with an embodiment of the invention.
FIG. 3 is a diagram of a network configuration.
DETALhED DESCRIPTION
Referring to FIG. 1, a network arrangement 10 used to
offer differentiated services is shown. A service provider
(not shown) offers a frame relay network 12 including X
redundant virtual circuits 14a-N (where X is an, integer and N
corresponds to the number of virtual circuits, X) between two
destinations, e.g., a first CPE (customer premise equipment)
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16 via a first switch (router) 18 and a second CPE 20 via a
second switch 22. The actual destinations of the data
(traffic) may be elements (not shown) having access to the
CPEs 16, 18 such as telephones, servers, computers, facsimile
machines, personal digital assistants, and pagers.
A frame relay protocol is a packet-switching protocol for
connecting devices on a network and for transmitting data
across the network in the proper order. The frame relay
protocol operates between the network and an end-user device,
e.g., customer premises equipment, a computer workstation, a
local area network (LAN), a router, a front-end processor, or
other device. In transmitting the data, the network may use
any type of transmission method compatible with the frame
relay protocol.
The path from an originating end-user device, through the
network, and to a destination end-user device is called a
virtual path or a-virtual circuit: A virtual circuit allows
the originating end-user device and the destination end-user
device to communicate as if they have a dedicated connection
even though the data transmitted between them may travel
different routes before reaching the proper destination.
Virtual circuits may be permanent or temporary. Permanent
virtual circuits (PVC) are permanently available, while
switched virtual circuits (SVC) are set-up on an as-needed
basis and must be reestablished for each data transmission.
The virtual circuits 14a-N in FIG. 1 allow computer
terminals 24 connected the CPE 16 via a LAN 26 and a router 28
to send data to other computer terminals 30 connected to the
CPE 20 via another LAN 32 and another router 34. The virtual
circuits 14a-N are redundant in the sense that they run
between the same destinations. Each of the virtual circuits
14a-N has different service quality attributes. When the
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first CPE 16 (or the second CPE 20) has data to send to the
second CPE 20 (or the first CPE 16), the switch 18 (or the
switch 22), using a signaling routine 36, signals the quality
characteristics of the virtual circuits 14a-N to the sending
CPE 16 (or the CPE 20). The CPE 16 (or the CPE 20), using a
decision-making routine 38, maps the virtual circuits 14a-N to
differentiated service classes and allocates traffic to the
virtual circuits 14a-N based on service requirements, e.g.,
QoS (quality of service), of the application that issued the
data. This functionality may be combined with frame relay
end-to-end multilink, as defined in the August 1999 Frame
Relay Forum voluntary technical standard FRF 15 entitled "End-
to-End Multilink Frame Relay Implementation Agreement," to
allow a single flow of data to be sent over a set of redundant
virtual circuits.
Referring to FIG. 2, a process 40 offers differentiated
services using the signaling routine 36 and the decision-
making routine38. The signaling routine 36 and the decision-
making routine 38 may be included in a single routine (not
shown) accessible by the CPE 16 and/or the switch 28. The
process 40 includes three stages: initialization 42,
classification 44, and transmission 46. The initialization
stage 42 involves evaluating the virtual circuits 14a-N.
Knowing the characteristics of the virtual circuits, 14a-N,
the classification stage 44 involves examining the data to
send across the virtual circuits 14a-N and choosing which
virtual circuits) 14a-N to use to send the data. The data
can then be shunted to a virtual circuits) 14a-N in the
transmission stage 46.
In the initialization stage 42, the signaling routine 36
signals 48 characteristics of each virtual circuit 14a-N to
the CPE having data to send (assume here that the sending CPE
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is the CPE 16). This implies that there should be a form of
signaling between the CPE 16 and the switch 18 that is richer
than traditional frame relay data link control management
protocols. Additionally, the switch network provisioning
system is enhanced to set up multiple virtual circuits between
endpoints, here the switches 18, 22. The protocol enables the
CPE 16 to recognize redundant virtual circuits and integrate
them into a differentiated services offering. One type of
protocol that may be used includes enhanced signaling and is
described in the April 6, 2000 Frame Relay Forum proposed
voluntary technical standard FRF 1.2, "PVC User-to-Network
Interface (UNI) Implementation Agreement."
The information that the switch 18 signals to the CPE 16
includes service parameters for each of the virtual circuits
14a-N. The service parameters provide the CPE 16 with
information to determine which virtual circuit 14a-N is best
suited for the particular type of.traffic that the CPE 16 has
to send. The virtual circuits 14a-N have individually
configurable service parameters. The service parameters have
default values. The default parameters include discard and
transit priorities for the virtual circuits 14a-N. For
example, a standard multimedia/data service pack of virtual
circuits, e.g., PVCs, is the Olympic model of a frame relay
network having three virtual circuits (X = 3, N = c),
colloquially called gold, silver, and bronze virtual circuits,
have default characteristics including:
~ gold, e.g., virtual circuit 14a: high transfer
and low discard priority for multimedia
applications;
~ silver, e.g., virtual circuit 14b: medium
transfer and discard priority for mission
critical applications; and
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~ bronze, e.g., virtual circuit 14c: low transfer
and discard priority for batch application.
Specific service parameters that the switch 18 signals to the
CPE 16 include:
~ committed burst size (Bc) - the number of
consecutive bits that the virtual circuit
agrees to carry without discarding data;
~ excess burst size (Be) - amount over the Bc
that the virtual circuit agrees to carry with a
greater likelihood that the data will be
discarded;
transmission interval (T);
~ frame transfer priority; and
~ frame discard priority.
At line initialization, the CPE 16 uses a protocol, e.g.,
an inverse (reverse) address resolution protocol (ARP), to
determine 50 the address, e.g., layer three address, at the
other end of the virtual circuits 14a-N. This implies that
the CPE 16 should be able to recognize common layer three
addresses that are discoverable via inverse ARP. The CPE 16
can use inverse ARP to discover its own Internet Protocol (IP)
address by broadcasting its physical address and receiving its
layer three address back. A layer three address includes
information such as message type and QoS requirements that the
CPE 16 can examine and use in prioritizing the data and
choosing a virtual circuit 14a-N. The CPE 16 also can group
52 all virtual circuits 14a-N that share a common layer three
address into service packs.
In the classification stage 44, the CPE 16 examines 54
the priority of data it has to send across the frame relay
network 12. The CPE 16 also looks at the type of data being
transmitted and the choice of virtual circuits 14a-N
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available. The CPE 16 makes 56 a forwarding decision based on
next-hop or per hop behavior. (PHB). The CPE 16 looks for a
low number of hops because the fewer the number of hops
between the data's source and destination, the less time is
required for the data to travel from the source to the
destination.
Each virtual circuit 14a-N within a service pack can be
mapped to a specific PHB. It is possible to interpret a
virtual circuit 14a-N as having a PHB of a certain type based
on the combination of discard and transfer priority associated
with the virtual circuit 14a-N. This determination is made by
bilateral agreement between the CPE 16 and the service
provider. Thus, for example, a virtual circuit with a
transfer priority of eight and a discard priority of seven
could represent an AF12 at one frame relay network and an EF
at another.
The classification of a data packet for forwarding can be
done using a simple mapping of the data's differentiated
services code point (DSCP) that indicates the level of service
desired. The DSCP maps the data to a particular forwarding
behavior, e.g., PHB, that provides service information, e.g.,
bandwidth, queuing, and discarding decisions, in accordance
with the frame relay network 12. The CPE 16 can then choose
58 the virtual circuit 14a-N that optimizes the QoS parameters
of the data stream and shunt 60 the data to the chosen virtual
circuits) 14a-N. In this way, the virtual circuits 14a-N are
chosen in a way that optimizes the QoS parameters of the
traffic being sent. The CPE 16 may also transmit
multiprotocol (non-IP) traffic over the virtual circuits 14a-N
as long as the CPE 16 takes into account the bandwidth lost in
doing so and makes sure that the virtual circuits 14a-N comply
with the IP service requirements.
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Referring to FIG. 3, a network arrangement 62 is shown
that can implement the process 40 (FIG. 2) over multiple frame
relay networks 64a-M and multiple virtual circuit segments
66a-M (a mufti-network virtual circuit 68) using routines 70,
72. The routine 70 implements the signaling routine 36 while
the routine 72 implements the decision-making routine 38, both
described above.
A number of embodiments of the invention have been
described. Other embodiments are within the scope of the
following claims.
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