U.S. patent application number 11/217586 was filed with the patent office on 2006-11-30 for system and method for retrying reservations in a rsvp environment.
This patent application is currently assigned to Cisco Technology, Inc.. Invention is credited to Rongxuan V. Chen, Subhasri Dhesikan, Keith A. Lantz, Kevin E. Miller, John K. JR. Restrick, James M. Stormes, Martin W. Wu.
Application Number | 20060268693 11/217586 |
Document ID | / |
Family ID | 37463179 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060268693 |
Kind Code |
A1 |
Dhesikan; Subhasri ; et
al. |
November 30, 2006 |
System and method for retrying reservations in a RSVP
environment
Abstract
A communication system includes a call agent that coordinates
and supervises communications between endpoints. The call agent
allocates a QoS agent for each endpoint involved in a call. The QoS
agents generate reservations for the call in order to provide the
call with a guaranteed amount of bandwidth and an established QoS.
Each endpoint or location associated with an endpoint has a
reservation policy that determines how calls are to be handled when
a reservation is or is not obtained and when a reservation is lost
or obtained during a call. The communication system is able to
handle reservations, or the lack thereof, during various situations
like on hold, call transfer, call forwarding, conference call, and
shared line services.
Inventors: |
Dhesikan; Subhasri; (San
Jose, CA) ; Miller; Kevin E.; (Cary, NC) ;
Chen; Rongxuan V.; (San Jose, CA) ; Restrick; John K.
JR.; (Palo Alto, CA) ; Wu; Martin W.; (Plano,
TX) ; Lantz; Keith A.; (Los Altos, CA) ;
Stormes; James M.; (Eatontown, NJ) |
Correspondence
Address: |
BAKER BOTTS L.L.P.
2001 ROSS AVENUE
SUITE 600
DALLAS
TX
75201-2980
US
|
Assignee: |
Cisco Technology, Inc.
|
Family ID: |
37463179 |
Appl. No.: |
11/217586 |
Filed: |
August 31, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11135697 |
May 24, 2005 |
|
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11217586 |
Aug 31, 2005 |
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Current U.S.
Class: |
370/229 ;
370/395.21 |
Current CPC
Class: |
H04L 47/70 20130101;
H04M 3/2227 20130101; H04L 47/724 20130101; H04L 47/745 20130101;
H04M 3/54 20130101; H04L 47/765 20130101; H04L 65/608 20130101;
H04L 41/5012 20130101; H04L 47/24 20130101; H04L 47/782 20130101;
H04L 47/20 20130101; H04L 65/1069 20130101; H04M 7/1275 20130101;
H04L 29/06027 20130101; H04L 65/80 20130101; H04M 3/428 20130101;
H04M 3/56 20130101; H04L 47/748 20130101; H04L 41/06 20130101; H04L
41/0896 20130101; H04L 41/5019 20130101; H04L 41/046 20130101; H04L
41/5087 20130101 |
Class at
Publication: |
370/229 ;
370/395.21 |
International
Class: |
H04L 12/26 20060101
H04L012/26; H04L 12/56 20060101 H04L012/56 |
Claims
1. A method for retrying reservations in a Resource Reservation
Setup Protocol (RSVP) environment, comprising: facilitating
communication between a first location and a second location during
a call using a first quality of service (QoS) agent and a second
QoS agent, wherein the first location is associated with the first
QoS agent and the second location is associated with the second QoS
agent; attempting to establish a reservation between a first
endpoint and a second endpoint, wherein the first endpoint is
associated with the first QoS agent and the first location and the
second endpoint is associated with the second QoS agent and the
second location; retrying the reservation between the first
endpoint and the second endpoint during a time interval in
accordance with the attempt to establish the reservation between
the first endpoint and the second endpoint.
2. The method of claim 1, wherein facilitating communication
between the first location and the second location includes
facilitating communication using an established reservation.
3. The method of claim 1, further comprising: determining whether a
reservation error has occurred during mid-call; retrying the
reservation mid-call in accordance with the determination whether
the reservation error has occurred during mid-call.
4. The method of claim 1, further comprising: determining whether a
reservation error has occurred during an initial call setup;
retrying the reservation during the initial call setup in
accordance with the determination whether the reservation error has
occurred during the initial call setup.
5. The method of claim 1, further comprising receiving a response
in accordance with retrying the reservation between the first
endpoint and the second endpoint.
6. The method of claim 1, further comprising granting resources for
the call between the first endpoint and the second endpoint in
accordance with retrying the reservation.
7. The method of claim 1, further comprising assigning the
reservation between the first endpoint and the second endpoint in
accordance with retrying the reservation.
8. The method of claim 7, further comprising providing an improved
quality of service between the first endpoint and the second
endpoint if the retried reservation is assigned between the first
endpoint and the second endpoint.
9. The method of claim 1, wherein facilitating communication
between a first location and a second location during a call
includes exchanging audio media between the first endpoint and the
second endpoint, wherein retrying the reservation between the first
endpoint and the second endpoint includes retrying the reservation
for the audio media.
10. The method of claim 1, wherein facilitating communication
between a first location and a second location during a call
includes exchanging video media between the first endpoint and the
second endpoint, wherein retrying the reservation between the first
endpoint and the second endpoint includes retrying the reservation
for the video media.
11. A computer readable medium including logic providing for
retrying reservations in a Resource Reservation Setup Protocol
(RSVP) environment, the logic operable to: facilitate communication
between a first location and a second location during a call using
a first quality of service (QoS) agent and a second QoS agent,
wherein the first location is associated with the first QoS agent
and the second location is associated with the second QoS agent;
attempt to establish a reservation between a first endpoint and a
second endpoint, wherein the first endpoint is associated with the
first QoS agent and the first location and the second endpoint is
associated with the second QoS agent and the second location; retry
the reservation between the first endpoint and the second endpoint
during a time interval in accordance with the attempt to establish
the reservation between the first endpoint and the second
endpoint.
12. The computer readable medium of claim 11, wherein facilitating
communication between the first location and the second location
includes logic operable to facilitate communication using an
established reservation.
13. The computer readable medium of claim 11, wherein the logic is
operable to determine whether a reservation error has occurred
during mid-call, the logic is operable to retry the reservation
mid-call in accordance with the determination whether the
reservation error has occurred during mid-call.
14. The computer readable medium of claim 11, wherein the logic is
operable to determine whether a reservation error has occurred
during an initial call setup, the logic is operable to retry the
reservation during the initial whether made that the reservation
error has occurred during the initial call setup.
15. The computer readable medium of claim 11, wherein the logic is
operable to receive a response in accordance with retrying the
reservation between the first endpoint and the second endpoint.
16. The computer readable medium of claim 11, wherein the logic is
operable to grant resources for the call between the first endpoint
and the second endpoint in accordance with retrying the
reservation.
17. The computer readable medium of claim 11, wherein the logic is
operable to assign the reservation between the first endpoint and
the second endpoint in accordance with retrying the
reservation.
18. The computer readable medium of claim 17, wherein the logic is
operable to provide an improved quality of service between the
first endpoint and the second endpoint if the retried reservation
is assigned between the first endpoint and the second endpoint.
19. The computer readable medium of claim 11, wherein the logic is
operable to facilitate communication between a first location and a
second location during a call includes logic operable to exchange
audio media between the first endpoint and the second endpoint, the
logic is operable to retry the reservation between the first
endpoint and the second endpoint includes logic operable to retry
the reservation for the audio media.
20. The computer readable medium of claim 11, wherein the logic is
operable to facilitate communication between a first location and a
second location during a call includes logic operable to exchange
video media between the first endpoint and the second endpoint, the
logic is operable to retry the reservation between the first
endpoint and the second endpoint includes logic operable to retry
the reservation for the video media.
21. A system for retrying reservations in a Resource Reservation
Setup Protocol (RSVP) environment, comprising: a first quality of
service (QoS) agent and a second QoS agent operable to facilitate
communication between a first location and a second location during
a call wherein the first location is associated with the first QoS
agent and the second location is associated with the second QoS
agent, the first QoS agent operable to attempt to establish a
reservation between a first endpoint and a second endpoint, wherein
the first endpoint is associated with the first QoS agent and the
first location and the second endpoint is associated with the
second QoS agent and the second location, the first QoS agent
operable to retry the reservation between the first endpoint and
the second endpoint during a time interval in accordance with the
attempt to establish the reservation between the first endpoint and
the second endpoint; a call agent coupled to the first QoS agent
and the second QoS agent, the call agent operable to manage the
first QoS agent and the second QoS agent.
22. The system of claim 21, wherein the first QoS agent and the
second QoS agent facilitate communication between the first
location and the second location using an established
reservation.
23. The system of claim 21, wherein the first QoS agent is operable
to determine whether a reservation error has occurred during
mid-call, the first QoS agent is operable to retry the reservation
mid-call in accordance with the determination whether the
reservation error has occurred during mid-call.
24. The system of claim 21, wherein the first QoS agent is operable
to determine whether a reservation error has occurred during an
initial call setup, the first QoS agent is operable to retry the
reservation during the initial call setup in accordance with the
determination whether the reservation error has occurred during the
initial call setup.
25. The system of claim 21, wherein the call manager is operable to
initiate a retry timer to determine when to retry the
reservation.
26. The system of claim 21, wherein the call manager is operable to
determine whether the retried reservation between the first
endpoint and the second endpoint is established.
27. The system of claim 21, wherein the first QoS agent is operable
to grant resources for the call between the first endpoint and the
second endpoint in accordance with the determination whether the
retried reservation is established.
28. The system of claim 21, wherein the call manager is operable to
assign the reservation between the first endpoint and the second
endpoint in accordance with the determination whether the retried
reservation is established.
29. The system of claim 28, wherein the first QoS agent is operable
to assign the reservation between the first endpoint and the second
endpoint in accordance with the determination whether the retried
reservation is established.
30. The system of claim 28, wherein the call manager is operable to
provide an improved quality of service between the first endpoint
and the second endpoint if the reservation is assigned between the
first endpoint and the second endpoint.
31. The system of claim 21, wherein the first endpoint and the
second endpoint are operable to exchange audio media, the first QoS
agent is operable to retry the reservation between the first
endpoint and the second endpoint for the audio media.
32. The system of claim 21, wherein the first endpoint and the
second endpoint are operable to exchange video media, the first QoS
agent is operable to retry the reservation between the first
endpoint and the second endpoint for the video media.
33. A system for retrying reservations in a Resource Reservation
Setup Protocol (RSVP) environment, comprising: means for
communicating between a first location and a second location during
a call using a first quality of service (QoS) agent and a second
QoS agent, wherein the first location is associated with the first
QoS agent and the second location is associated with the second QoS
agent; means for attempting to establish a reservation between a
first endpoint and a second endpoint, wherein the first endpoint is
associated with the first QoS agent and the first location and the
second endpoint is associated with the second QoS agent and the
second location; means for retrying the reservation between the
first endpoint and the second endpoint during a time interval in
accordance with the attempt to establish the reservation because
the first endpoint and the second endpoint.
34. The system of claim 33, further comprising means for assigning
the reservation between the first endpoint and the second endpoint
in accordance with retrying the reservation.
35. The system of claim 34, further comprising means for providing
an improved quality of service between the first endpoint and the
second endpoint if the retried reservation is assigned between the
first endpoint and the second endpoint.
Description
RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
application Ser. No. 11/135,697 filed May 24, 2005.
TECHNICAL FIELD OF THE INVENTION
[0002] This invention relates generally to the field of
telecommunications and more specifically to a system and a method
for retrying reservations in a RSVP environment.
BACKGROUND OF THE INVENTION
[0003] The field of communications has become increasingly
important in today's society. In particular, the ability to quickly
and effectively interact with an individual through any suitable
communications media presents a significant obstacle for component
manufacturers, system designers, and network operators. This
obstacle is made even more difficult due to the plethora of diverse
communication technologies that exist in the current marketplace.
Because of the many communication technologies, many components
cannot interact with each other. As new communication platforms
become available to the consumer, new protocols need to be
developed to optimize these emerging technologies.
SUMMARY OF THE INVENTION
[0004] In accordance with the present invention, disadvantages and
problems associated with previous techniques for implementing a
retry policy in a Resource Reservation Protocol (RSVP) environment
in a communication system may be reduced or eliminated.
[0005] According to one embodiment of the present invention a
communication system is provided that includes a call agent
controlling the setup of a call between two or more endpoints. The
call agent interacts with a quality of service (QoS) agent that
establishes reservations between endpoints in order to guarantee a
certain amount of bandwidth for the call. The QoS agents provide
information concerning obtained and failed reservations between
endpoints to the call agent so that the call agent can establish an
appropriate connection for the call between the endpoints. The call
agent implements different pre-call and mid-call reservation
policies and initiates procedures to obtain a reservation for the
call upon a failure.
[0006] Certain embodiments of the invention may provide one or more
technical advantages. A technical advantage of one embodiment may
be that RSVP can be used in a system without having to touch every
endpoint. The endpoints may support different protocols and
interact with RSVP within the same system. Furthermore, endpoints
that are RSVP-enabled can communicate with non-RSVP enabled
endpoints. Another technical advantage of another embodiment may be
that calls do not fail if a RSVP reservation is not secured with
the initial attempt. Allowing calls to proceed without a RSVP
reservation prevents complete call failure. Yet another technical
advantage of an embodiment may be that calls may gain a reservation
during a call, which improves the QoS, or may restore a reservation
that fails mid-call, which also improves a call's QoS.
[0007] Certain embodiments of the invention may include none, some,
or all of the above technical advantages. One or more other
technical advantages may be readily apparent to one skilled in the
art from the figures, descriptions, and claims included herein.
BRIEF DESCRIPTION OF THE FIGURES
[0008] For a more complete understanding of the present invention
and its features and advantages, reference is now made to the
following description, taken in conjunction with the accompanying
figures, wherein like reference numerals represent like parts, in
which:
[0009] FIG. 1 is a simplified block diagram illustrating a
communication system that may implement a reservation feature;
[0010] FIGS. 2A-2C represent a flowchart and message flows
illustrating an embodiment of a method for securing a reservation
in the communication system;
[0011] FIGS. 3A, 3Ba, and 3Bb represent a flowchart and a message
flow illustrating an embodiment of a method for retrying a
reservation in the communication system;
[0012] FIG. 4 is a flowchart illustrating an embodiment of a method
for implementing a mid-call policy in the communication system;
[0013] FIGS. 5A-5B represent a flowchart and a message flow
illustrating another embodiment of a method for securing both an
audio and a video stream in the communication system;
[0014] FIGS. 6A-6B represent a flowchart and a message flow
illustrating an embodiment of a method for preserving bandwidth in
an on hold situation;
[0015] FIGS. 7A-7B represent a flowchart and a message flow
illustrating another embodiment of a method for preserving
bandwidth in a call transfer situation;
[0016] FIG. 8 is a flowchart illustrating another embodiment of a
method for preserving bandwidth in a conference call situation;
[0017] FIG. 9 is a flowchart illustrating another embodiment of a
method for preserving bandwidth in a call forwarding situation;
[0018] FIGS. 10A-10B represent message flows illustrating a shared
line situation;
[0019] FIG. 11 is a flowchart illustrating an embodiment for
activating video media during a connected call.
DETAILED DESCRIPTION OF THE INVENTION
[0020] FIG. 1 is a simplified block diagram of a communication
system 10 for implementing a reservation feature within the
Resource Reservation Protocol (RSVP), which can optimize
communications, in any suitable environment. Communication system
10 includes a call agent 100 that manages calls in one or more
locations 102. The call agent 100 allows the locations 102 to
communicate internally and with other locations 102 using the
reservation feature at suitable times. Within a location 102, such
as location 102a or 102b, there may be a plurality of endpoints 106
that receive and originate media flows. As shown, location 102a has
endpoints 106a, 106b, and 106c. Location 102b has endpoints 106d,
106e, and 106f. Each location 102a and 102b includes a QoS (QoS)
agent 104a and 104b that controls the implementation of RSVP.
[0021] Call agent 100 is a centralized entity that controls the
exchange of media between locations 102a and 102b and between
individual endpoints 106 within locations 102a and 102b. Call agent
100 may also be responsible for RSVP signaling. As a result, call
agent 100 is located within the signaling path. Call agent 100 may
be configured to reflect the Reservation handling policies. Call
agent 100 may include a user interface that receives configuration
information. For example, a user may configure the Reservation
handling policy of locations 102a and 102b at call agent 100.
[0022] Locations 102a and 102b are logical groupings of endpoints
within communication system 10 and are not necessarily based on
geographic location. Each location 102 represents a series of
points or nodes of interconnected communications paths for
receiving and transmitting packets of information that propagate
through communication system 10. Locations 102 may communicate with
each other or with other devices and locations where appropriate.
Each location 102 may offer some service or capability to an
endpoint or set of endpoints. Locations 102 may also be connected
to one or more additional network elements. For example, locations
102 may be connected to a service provider network. Location 102
may also include the functionality of call agent 100. Locations 102
may be any suitable architecture, such as a local area network
(LAN), an enterprise network, a virtual private network (VPN), a
metropolitan area network (MAN), or a wide area network (WAN) or
any other appropriate architecture or system that facilitates
communications.
[0023] Endpoints 106 establish a communication tunnel, link, or
session in communication system 10 via locations 102. Endpoints 106
may be configured to implement a specific Reservation handling
policy when attempting to secure a reservation. Endpoints 106 may
include Skinny Client Control Protocol (SCCP) telephones, Session
Initiation Protocol (SIP) telephones, a computer, a personal
digital assistant, a laptop, videoconferencing devices, gateways,
or any other suitable endpoint. Endpoints 106 may be enabled by any
protocol such as SCCP, SIP, H.323, Media Gateway Control Protocol
(MGCP), or any other suitable protocol. In the illustrated
embodiment, location endpoint 106a may be an Internet protocol
telephone, endpoint 106b may be a computer and endpoint 106c may be
a gateway. For location 102b, endpoint 106d may be a SIP telephone,
endpoint 106e may be a gateway, and endpoint 106f may be a
videoconferencing device.
[0024] QoS agents 104a and 104b, respectively, are coupled to an
associated call agent 100 and to associated endpoints 106. QoS
agents 104 represent endpoints 106, reserve bandwidth on behalf of
endpoints 106, and are involved in the signaling and media exchange
between endpoints 106 as determined by call agent 100. QoS agents
104 control the implementation of RSVP by determining the available
bandwidth and making reservations on behalf of endpoints 106. A
call leg and a signaling path may be created by any one of QoS
agents 104. QoS agents 104 may be switches, gateways, bridges,
voice-mail servers, routers, and load balancers. Using QoS agents
104, RSVP support is extended to calls established by any
appropriate protocol such as a real-time protocol (RTP), a user
datagram protocol (UDP), SCCP, SIP, H.323, or any other appropriate
type of protocol or technology. QoS agents 104 may also accommodate
audio and video media streams, audio and video conferences, and
perform appropriate transcoding operations.
[0025] QoS agents 104 may provide Differentiated Services Code
Point (DSCP) marking of each packet in the media stream. DSCP
marking specifies the class of service for each packet. The DSCP
marking is updated based on the outcome of the reservation
function. Call Agent 100 will allow for special DSCP markings that
indicate a different level of service for calls that fail to obtain
a reservation or lose a reservation during the call. Thus, by
utilizing different DSCP values, Call Agent 100 can prevent calls
from failing even if the call is preempted by the network.
[0026] QoS agents 104 may also support Multi-Level Precedence and
Preemption (MLPP), in which calls with a higher priority
designation may preempt calls with a lower priority designation.
Call Agent 100 passes caller precedence levels to QoS agents 104 in
a QoS message. This allows a router to preempt a flow based on the
precedence level. QoS agents 104 notify call agent 100 about
reservation failures as a result of preemption. Call agent 100
handles the preemptions as per configured policies and notifies the
endpoints 106 if the call is to be preempted.
[0027] RSVP is a transport level signaling protocol for reserving
resources in an unreliable Internet Protocol (IP) based network
using a reservation. RSVP provides an alternate call admission
control mechanism within call agent 100. Customers in today's
telecommunications environment are attempting to move away from a
hub and spoke network topology for video conferencing and video
telephony applications. The use of RSVP will assist in realizing
this goal. Important features of RSVP include making a reservation
of bandwidth for a particular session, which is a flow that has a
particular destination address, destination port, and protocol
identifier. RSVP messages travel along the same path as the media
flow in a unidirectional manner. Thus, flows are reserved in one
direction only and each session is treated as an independent unit.
RSVP messages flow transparently through non-RSVP routers and
switches. RSVP supports unicast and multicast environments and is
receiver oriented in that the receiver of the stream requests the
reservation. By having a reservation, a call can utilize reserved
bandwidth and experience improved QoS.
[0028] For a brief overview of call operation, caller endpoint 106a
attempts to contact callee endpoint 106d. If call agent policies
provide for RSVP in establishing a given call, call agent 100
allocates resources of QoS agents 104 for calling and called
parties. Call agent 100 instructs QoS agents 104a and 104b to
attempt RSVP reservation on behalf of endpoints 106a and 106d. QoS
agent 104a initiates a PATH message that contains a description or
advertisement of the desired traffic flow. The PATH message travels
from QoS agent 104a to QoS agent 104b along the same path as that
of the media flow. Any RSVP-capable network devices along the path
will collect appropriate information from the PATH message and
store it as path state. When QoS agent 104b receives a PATH
message, it can request resources for the media flow described in
the PATH message by transmitting a RESV message. The RESV message
is transmitted along the reverse path as that of the PATH message
and the media flow. Each RSVP-capable device along the reverse path
receives the RESV message and decides whether to accept or deny the
request. If the request is accepted, then the necessary state is
stored and the RESV message is forwarded down the reverse path. If
the request is denied, a RESVERR message is generated and sent
along the original path and the RESV message is not forwarded any
further. The establishment of a one-way RSVP reservation
successfully completes when the QoS agent 104a receives a RESV
message in response to its PATH message. Upon securing a
reservation, call agent 100 rings callee endpoint 106d. Caller
endpoint 106a and callee endpoint 106d can then exchange media.
[0029] Whether a reservation is required for a given call depends
on a Reservation handling policy configured for a location or
endpoint. Calls within the same location may not require a
reservation by default. Any type of Call Admission Control (CAC)
may be used when RSVP is not implemented for a particular call. The
Reservation handling policy for the location or endpoint may be
configured by the user. A location's or endpoint's Reservation
handling policy may be one of the following: no reservation (none),
audio and video reservation mandatory (audio/video mandatory),
audio reservation mandatory and video optional (video optional), or
audio reservation optional and video optional (audio optional).
Though for discussion purposes only four Reservation handling
policies are mentioned, other Reservation handling policies may be
implemented as well, such as for example a video mandatory and
audio optional Reservation handling policy. A no reservation policy
means that a reservation is not necessary to connect a call. The
call may be connected through another call admission control
mechanism. In an embodiment, this may be the default for endpoints
within the same location. For an audio/video mandatory policy, a
call cannot be connected until every media stream being transmitted
receives a RSVP reservation. If a reservation is not successful for
any one of the media streams, the call will be released. For
example, if an audio stream receives a reservation but a video
stream does not receive a reservation, the call will be released.
Under a video optional policy, the audio stream of a call will not
be connected until a RSVP reservation succeeds. The call may
connect with only audio and video can be added to the call if a
reservation for the video stream succeeds. An audio optional policy
does not require a reservation to be established for an audio
stream before the call proceeds. An attempt may be made to secure a
RSVP reservation, but the call will proceed regardless of the
reservation's success. The call may not have a high QoS, but will
proceed with a "best efforts" quality. A video stream in an audio
optional policy will only be available if the RSVP reservation
succeeds for the video stream. Table I provides a summary of the
different Reservation handling policy procedures to be discussed in
greater detail below. TABLE-US-00001 TABLE I INITIAL RESERVATION
MID-CALL RESERVATION POLICY POLICY ACTION RESULT Mandatory Audio
N/A Initial audio Call fails to initiate Mandatory Video failure
Mandatory Audio N/A Initial video Call fails to initiate Mandatory
Video failure Mandatory Audio Fail after x retries Mid-call audio
Call fails if unable to Mandatory Video failure secure reservation
after x retries Mandatory Audio Fail after x retries Mid-call video
Call fails if unable to Mandatory Video failure secure reservation
after x retries Mandatory Audio Best effort and Mid-call audio
Audio proceeds as best Mandatory Video continue retries failure
effort until reservation is successful Mandatory Audio Best effort
and Mid-call video Call proceeds as audio Mandatory Video continue
retries failure call until video reservation is secured. Mandatory
Audio & N/A Initial audio Call fails video if reservation
failure successful Mandatory Audio & N/A Initial video Call
proceeds as audio video if reservation failure call successful
Mandatory Audio & Fail after x retries Mid-call audio Calls
fails if unable to video if reservation failure secure reservation
after successful x retries Mandatory Audio & Fail after x
retries Mid-call video Call proceeds as audio video if reservation
failure call until video successful reservation is secured.
Mandatory Audio & Best effort and Mid-call audio Audio proceeds
as best video if reservation continue retries failure effort until
reservation successful is successful Mandatory Audio & Best
effort and Mid-call video Call proceeds as audio video if
reservation continue retries failure call until video successful
reservation is secured. Optional Audio & N/A Initial audio
Audio proceeds as best video if reservation failure effort until
reservation successful is successful Optional Audio & N/A
Initial video Call proceeds as audio video if reservation failure
call successful Optional Audio & Best effort and Mid-call audio
Audio proceeds as best video if reservation continue retries
failure effort until reservation successful is successful Optional
Audio & Best effort and Mid-call video Call proceeds as audio
video if reservation continue retries failure call until video
successful reservation is secured.
[0030] The QoS for a call may be managed through a mixture of RSVP
and any other types of Call Admission Control mechanisms. It may
not be possible for the RSVP functionality to be operational over
the entire communication system 10. Thus, some devices in some
locations of communication system 10 will have a QoS agent
configuration while other devices may not. As an example, when a
call is initiated from a location that has RSVP capability to
another location that is not RSVP enabled, call agent 100 will
manage the QoS for the call using both mechanisms. The first part
of the call, from the RSVP enabled location to a hub or central
site that is RSVP enabled, will be processed through the RSVP
mechanism. The second part of the call, from the hub or central
site to the non-RSVP capable location, will be managed through
another Call Admission Control type. If either mechanism fails to
allocate appropriate bandwidth, the call fails. Since other Call
Admission Control types may not have any optional policy, the call
will be rejected if there is not enough location bandwidth. There
will not be a best efforts call as is available under the RSVP
mechanism. Accordingly, if the QoS for a call is managed by both a
separate Call Admission Control mechanism and a RSVP mechanism, the
Reservation handling policy only affects the portion of the call
that is managed by the RSVP mechanism. For the port of the call
managed by another Call Admission Control, only mandatory policy
behavior is supported and the call either succeeds or fails with no
possibility for degraded best efforts service for the call.
[0031] Modifications, additions, or omissions may be made to the
system without departing from the scope of the invention. For
example, locations 102 can be changed, modified, rearranged, or
reconfigured to achieve their intended operations as they pertain
to the reservation function. In an embodiment, the functions of
call agent 100 may be distributed to more than one call agent 100,
which decentralizes the functions of call agent 100. For example, a
separate call agent 100 may be associated with each location 102.
Between locations 102a and 102b, numerous pieces of network
equipment may be present, including routers, switches, WAN-links,
or any other suitable piece of network equipment.
[0032] Software, hardware, or a combination of the preceding may
reside in QoS agents 104 to achieve the reservation function and
the many features associated with the reservation function. QoS
agents 104 may be in call agent 100, in the media path of the media
stream, in a remote location, or in any suitable position to exact
the reservation function. In another embodiment, QoS agents 104 may
be included in endpoint 106 where endpoint 106 functions as a QoS
agent 104. These elements may be equipped with, or include, any
suitable component, device, application specific integrated circuit
(ASIC), processor, microprocessor, algorithm, read-only memory
(ROM), random access memory (RAM), erasable programmable ROM
(EPROM), electrically erasable programmable ROM (EEPROM),
field-programmable gate array (FPGA), or any other suitable element
or object that is operable to facilitate the operations of the
element. Additionally, any suitable logic comprising software,
hardware, other logic, or any suitable combination of the preceding
may perform the functions of communication system 10.
[0033] FIG. 2A is a flowchart 20 illustrating one embodiment of a
method for securing a reservation in communication system 10. At
block 200, the Reservation handling policy of location 102 of
endpoint 106 is determined. Determining the Reservation handling
policy of locations 102 allows call agent 100 to determine whether
a reservation is needed for the call. At decision block 202, if it
is determined that the Reservation handling policy is a no
reservation policy, endpoints 106 begin exchanging media at block
204. If the Reservation handling policy is not a no reservation
policy, call agent 100 determines whether the Reservation handling
policy is a mandatory Reservation handling policy at decision block
206. Upon determining that the Reservation handling policy is not a
mandatory Reservation handling policy, which means the Reservation
handling policy is an optional Reservation handling policy, call
agent 100 simultaneously instructs QoS agent 104 to attempt
securing a reservation and rings a callee endpoint 106d at block
208. Decision block 210 determines whether a reservation has been
secured for the optional Reservation handling policy. If a
reservation is secured, the endpoints exchange media with a high
QoS and the method proceeds at block 220. If a reservation is not
secured, call agent 100 may proceed at "A" in FIG. 3A. The call
connects at a lower QoS at block 212, and endpoints 106 exchange
media.
[0034] At decision block 206, if the Reservation handling policy is
determined to be a mandatory Reservation handling policy, call
agent 100 instructs QoS agent 104 to attempt to secure a
reservation at block 214. If a reservation is not secured at block
216, call agent 100 will exercise a reservation failure option at
block 218. The reservation failure options for mandatory
Reservation handling policy calls may include re-routing the call
through a Public Switched Telephone Network (PSTN), releasing the
call, or any other suitable reservation failure option. The
reservation failure option may include connecting the call with
degraded service. In order to prevent a call failure due to lack of
a reservation, the call can be allocated as a different class of
call and to a low priority queue in routers between the two
endpoints 106 with a degraded level of service. If QoS agent 104
secures a reservation, the call between endpoints is connected and
the exchange of media begins at block 220. Call agent 100 sends
reserve commands to the appropriate QoS agents 104 upon a
reservation being secured. After the reservation is secured, call
agent 100 alerts callee endpoint 106d and connects the call between
caller endpoint 106a and callee endpoint 106d.
[0035] From block 220, call agent 100 determines at block 222
whether the connected call has experienced a failing event. A
failing event may include a call being preempted by another call
that has a higher priority, a call that has insufficient bandwidth
to continue, or any suitable failing event. Instead of the call
being released because the failing event has occurred, the call
continues with degraded service. For example, the degraded service
may involve using a lower DSCP marking value, which lowers the QoS
of the call. To continue the call with degraded service and support
another call, the bandwidth originally supporting the call is
reallocated based on the availability of the QoS.
[0036] In the illustrated embodiment, communication system 10
allows higher priority calls to preempt lower priority calls.
Preempting the lower priority call may allow the higher priority
call to use the reservation once secured by the lower priority
call. In an embodiment, communication system 10 may not support
MLPP and does not allow preemption. If the call has not been
preempted, the exchange of media continues between endpoints 106 at
the higher QoS. If the call has been preempted, endpoints 106
continue exchanging media at block 224 using a lower DSCP marking
value, which means the media exchange has a lower priority and may
not receive the best QoS. At block 226, an attempt is made to
obtain a higher DSCP marking value during the call while the media
exchange continues. Obtaining a higher DSCP marking value during
the call improves the call's QoS. From block 226, the method may
continue from "A" in FIG. 3. The call terminates at block 228 and
the method subsequently ends.
[0037] FIG. 2B illustrates an example message flow among endpoints
106a and 106d, QoS agents 104a and 104b, and call agent 100 when a
reservation for an audio stream is mandatory. The sample call flow
refers to a scenario where both endpoints 106a and 106d are SCCP
phones. Changes to the call flow where one or both of endpoints
106a and 106d are SIP endpoints will be pointed out in the
following discussion.
[0038] When call agent 100 receives an inbound call request from
endpoint 106a, call agent 100 first checks the Reservation handling
policy for the call between endpoints 106a and 106d before
extending the call to endpoint 106d. If the Reservation handling
policy is audio/video mandatory or video optional for the call,
call agent 100 allocates QoS agent 104a for endpoint 106a and QoS
agent 104b for endpoint 106d. Call agent 100 sends a RTPPortReq
message to both QoS agents 104a and 104b to open RTP receiving
ports for two-way audio streams. Call agent 100 instructs QoS
agents 104a and 104b to listen on the receiving ports.
[0039] For the reservation from endpoint 106a to 106b, call agent
100 sends a QoSPath message to QoS agent 104a to instruct QoS agent
104a to initiate a PATH message to QoS agent 104b. Upon receiving
the PATH message, QoS agent 104b sends a RESV message towards QoS
agent 104a. The RESV message is transmitted along the reverse path
as that of the PATH message and the traffic flow. When QoS agent
104a receives the RESV message, it notifies call agent 100 about
the reservation status by sending a QoSRESVNotify message. A
similar message flow applies for the reservation from endpoint 106d
to endpoint 106a. A similar message flow will also occur for any
video or data streams associated with the call between endpoints
106a and 106d.
[0040] Upon successful reservations of both audio streams, call
agent 100 rings endpoint 106d and provides a ring back to endpoint
106a. When endpoint 106d goes off hook, call agent 100 connects the
audio media between endpoints 106a and 106d. Upon one of endpoints
106a and 106d going on hook and terminating the call, call agent
100 instructs QoS agents 104a and 104b to tear down the RSVP
reservation by sending a QoSTearDown message along with a direction
parameter. For the send direction, the appropriate QoS agent
initiates a PATHTear message. For the receive direction, the
appropriate QoS agent initiates a RESVTear message. RSVP
reservation teardown is independent of media stop streaming as
media may stop streaming while an RSVP reservation still needs to
be preserved. This is needed in the event of a hold/resume
situation where an endpoint is placed on hold and the reservation
is preserved in order to resume the call. Similar tear down message
transfers will occur for a video or data stream accompanying any
audio stream.
[0041] Call agent 100 can support different types of devices at
endpoints 106a and 106d other than the SCCP phones described above.
For example, an endpoint 106 may use a SIP device. The initial off
hook and dial message found with SCCP devices are replaced with an
INVITE message. The ringing, ring back, and off hook messages found
with the use of SCCP devices are replaced by an INVITE message
provided by call agent 100 to QoS agent 104b, a RINGING message
provided by QoS agent 104b to call agent 100, a 200 OK message from
QoS agent 104b to call agent 100 an ACK message from call agent 100
to QoS agent 104b, a 200 OK message from call agent 100 to QoS
agent 104a, and an ACK message from QoS agent 104a to call agent
100. At this point, media is streaming between endpoints 106a and
106d. The on hook message (assuming the example of endpoint 106d
going on hook first) is replaced by a BYE message from QoS agent
104b to call agent 100, a 200 OK message from call agent 100 to QoS
agent 104b, a BYE message from call agent 100 to QoS agent 104a,
and a 200 OK message from QoS agent 104a to call agent 100.
[0042] For an endpoint 106 using a H323 device, the initial off
hook and dial message is replaced by a H225Setup message. The
ringing, ring back, and off hook messages found with the use of
SCCP devices are replaced by a H225Setup message provided by call
agent 100 to QoS agent 104b, a H225Alert message provided by QoS
agent 104b to call agent 100, a H225Alert message provided by call
agent 100 to QoS agent 104a, a H225Alert message from QoS agent
104b to call agent 100, and a H225Alert message from call agent 100
to QoS agent 104a. Call agent 100 can also support other types of
endpoints 106 and also supports the implementation where endpoint
106a has a different type of device than endpoint 106d.
[0043] For the audio/video mandatory Reservation handling policy, a
failure in acquiring a reservation for both the audio stream and
the video/data stream in the direction from endpoint 106a to
endpoint 106d results in call agent 100 rejecting the call setup
request from the calling endpoint 106a. For the video optional
Reservation handling policy, call agent 100 rejects call setup if a
reservation is not obtained for an audio stream from endpoint 106a
to endpoint 106d. The same rejection applies if reservations from
endpoint 106d to endpoint 106a are not obtained for the call. It
may be possible to have a Reservation handling policy for endpoint
106a that is different than the Reservation handling policy for
endpoint 106d. Call agent 100 will reject any call setup requiring
a reservation that is not obtained.
[0044] FIG. 2C shows a message flow when call agent 100 is
connecting the media upon successful reservation of each audio
stream. When obtaining the reservations for each stream, call agent
100 will not know the exact bandwidth to use for the call before
connecting the media. At this time, call agent 100 provides
estimated bandwidth information in the QoSPath message. For an
audio call, call agent 100 may use any estimated bandwidth between
endpoints 106a and 106d determined in any manner. For a video call,
call agent 100 may use a desired minimum value default video
bandwidth. Upon connecting the media, call agent 100 can instruct
QoS agents 104a and 104b to adjust RSVP bandwidth reservation for
the call via a QoSModifyTSpec message. After each one-way media
stream is established, call agent 100 can instruct QoS agents 104a
and 104b to adjust bandwidth specifications if it is different from
the one used in the QoSPath and QoSResv messages.
[0045] FIG. 3A is a flowchart 30 illustrating an embodiment of a
method for retrying a reservation in communication system 10. The
blocks in flowchart 30 may be within flowchart 20 of FIG. 2A. At
block 300, call agent 100 determines whether a reservation error
has occurred during the media exchange. A reservation error may
include a mid-call failure or an initial call setup failing to
secure a reservation. For example, a reservation error may occur
when a call is preempted, when routers become inoperable during a
call, or when any other error occurs that may cause a reservation
to fail. A reservation error may occur if endpoints 106 lose an
established reservation mid-call, or if endpoint 106, having an
optional policy, cannot secure a reservation during the initial
call setup. Retrying a reservation may occur for an optional
Reservation handling policy call if a reservation is not secured
initially or during mid-call, may occur for a mandatory Reservation
handling policy call that fails mid-call, or may occur for any
suitable policy that fails at any time during the call. If call
agent 100 does not recognize an error, endpoints 106 continue
exchanging media and checking for a reservation error. Through this
retry mechanism, a call originally initiated with no reservation
and no QoS priority can obtain a reservation and improved QoS
during the call when resources and bandwidth-become available.
[0046] If a reservation error is detected, call agent 100 initiates
an internal retry timer at block 302. Call agent 100 includes a
retry timer that sets at what time interval to retry securing a
reservation. Alternatively, call agent 100 may set a count value
establishing a total number of times retry is attempted. At block
304, QoS agent 104 attempts to secure a reservation during the time
interval set on the retry timer. At decision block 306, a
determination is made whether a reservation was secured during the
time interval. If a reservation is secured, the call continues and
endpoints 106 exchange media at block 308. The call may terminate
at block 310 and the method subsequently ends. If reservations are
lost in the middle of a call due to link/node or other failures,
the failure situation may correct itself within a small amount of
time. The retry timer or count avoids the teardown of a call
immediately upon receiving a failure indication and allows call
agent 100 to maintain the connection for the call and retry
obtaining the lost reservations for a short period of time before
the call fails.
[0047] If a reservation is not secured at decision block 306, call
number 100 determines whether the time interval has exceeded or a
maximum count has been reached at block 312. If not, the time
interval or count is updated and QoS agent 104 retries to secure
the reservation. If so, the method may proceed to "B" in FIG. 4. If
N retries has not occurred at block 314, the method continues to
retry securing a reservation.
[0048] FIGS. 3Ba-3Bb show an example message flow between endpoints
106a and 106d, QoS agents 104a and 104b, and call agent 100 when a
reservation for an audio stream is optional. This message flow also
covers the retry scenarios of when a reservation is not required to
connect endpoints 106 and when a reservation is lost or obtained
after endpoints 106 begin exchanging media. When a reservation is
not required to connect endpoints 106a to 106d, call agent 100 will
send a RING message to endpoint 106d and begin simultaneously
obtaining a reservation in parallel. Whether or not a reservation
is obtained prior to endpoint 106d going off hook, a connection
will be made between endpoint 106a and 106b. In an example, call
agent 100 passes a retry=true state and retryTimer value to QoS
agents 104a and 104b in the QoSPath and QoSListen messages. When
QoS agents 104a and 104b receive the QoSListen message, a
ListenTimer is started. If either QoS agents 104a or 104b do not
receive a PATH message before expiration of the ListenTimer, a
QoSErrorNotify message is sent to call agent 100. At this time, if
the Reservation handling policy was mandatory for the media stream,
call agent 100 would reject the call setup request from the calling
endpoint. In the optional scenario, call agent 100 merely logs the
error. If QoS Agents 104a or 104b receive a PathError message, a
path retry timer is started and a new PATH message is sent upon
expiration of the timer. QoS agents 104a and 104b need only notify
call agent 100 whenever there is a status change from an error
condition to a non-error condition and vice versa in order to avoid
repeatedly sending error messages to call agent 100.
[0049] FIG. 4 is a flowchart 40 illustrating one embodiment of a
method for implementing a mid-call policy in communication system
10. The blocks included in flowchart 40 may be within flowchart 30
of FIG. 3A at any suitable place. The mid-call policy may be used
to determine how a call proceeds when an attempt to secure a
reservation is re-tried or may be used when a mid-call failure
occurs. A mid-call failure may occur if a router becomes inoperable
during the call or the reservation is lost for any reason. At block
400, the mid-call policy of location 102 of endpoint 106 is
determined. Call agent 100 applies the mid-call policies, and the
mid-call policies may be configured to be any suitable policy. For
example, the mid-call policy may be a no reservation policy, a
mandatory policy, or an optional policy. The mid-call policy may be
the same as or independent of the original Reservation handling
policy for the endpoints involved. Thus, a call may have a
mandatory Reservation handling policy at initial setup but may have
a weaker policy in response to any mid-call failures. This will
prevent a call failure from occurring during the middle of media
exchange between endpoints 106.
[0050] If it is determined at decision block 402 that the mid-call
policy is a no reservation policy, endpoints 106 exchange media at
block 404 and the call eventually terminates at block 418. However,
if the mid-call policy is not a no reservation mid-call policy, it
is determined whether the mid-call policy is a mandatory mid-call
policy at block 406. If the mid-call policy is not a mandatory
mid-call policy, which means the mid-call policy is an optional
mid-call policy, the call proceeds with "best efforts" at block 408
and eventually terminates at block 418. Proceeding with "best
efforts" allows the call to continue with the best available
service, even though the service is not of the highest quality. A
retry procedure may occur at block 409 to secure a reservation for
this call. If a reservation is not secured at block 410, retry
efforts will continue. If a reservation is secured at block 410,
media is exchanged with the secured reservation at block 411.
[0051] With a mandatory mid-call policy, call agent 100 determines
mid-call handling of the mandatory mid-call policy at block 412. If
the mid-call handling is not "best efforts" at decision block 413,
a reservation failure option will be exercised at block 414. The
reservation failure options for a mid-call policy include
re-routing the call through a PSTN, releasing the call, or any
other suitable reservation failure option. A reservation failure
option may also involve a one-time reservation retry in an attempt
to obtain a reservation for the call prior to terminating the
connection between the endpoints. If the mid-call handling is "best
efforts," the call proceeds with the best available service and
retries the RSVP reservation at block 416. The call terminates at
block 418 and the method subsequently ends.
[0052] After resources between two endpoints 106 have been reserved
and media is streaming between the two endpoints 106, a situation
may arise where the reservation is lost. In an example situation
shown in FIGS. 3Ba-3Bb, QoS agent 104a receives a RESVError message
indicating that the reservation it established for endpoint 106a to
receive media from endpoint 106d has been lost. QoS Agent 104a will
send a QoSErrorNotify message to inform call agent 100 of the lost
reservation. Call agent 100 will send an UpdateDSCP message to QoS
agent 104b in order to change the DSCP marking to a lower class of
service. QoS agent 104a will start a ResvRetryTimer and then check
for a valid PATH state. If there is a valid PATH state, QoS agent
104a will send a RESV message in order to recover the reservation.
If the PATH state is still not valid, QoS agent 104a will reset the
ResvRetryTimer. Upon receipt of the RESV message, QoS agent 104b
will inform call agent 100 by sending a QoSResvNotify message. Call
agent 100 will then send an UpdateDSCP message to QoS agent 104b in
order to reset the DSCP marking to a higher class of service.
[0053] The features discussed with respect to FIGS. 2A, 2B, 3A,
3Ba, 3Bb, and 4 may also apply to a call exchanging both audio and
video streams. The features apply to each media stream separately.
For example, if a video stream fails during a call, call agent 100
and QoS agent 104 may retry securing the reservation for the video
stream while endpoints 106 continue exchanging the audio
stream.
[0054] FIG. 5A is a flowchart 50 illustrating another embodiment,
expanding on the concepts of FIGS. 2A and 2B, of a method for
securing both a video and audio stream reservation in communication
system 10. FIG. 5B shows an example message flow for an audio with
video call. At block 500, the Reservation handling policy of the
location is determined. If the Reservation handling policy is
determined not to be a mandatory Reservation handling policy at
decision block 502, which means the Reservation handling policy is
an optional Reservation handling policy, an attempt is made to
secure a reservation for each media stream, a reservation for the
audio stream and a reservation for the video stream, at block 504.
Call agent 100 also rings endpoint 106d at block 504 and the method
continues to block 508. If the Reservation handling policy is a
mandatory Reservation handling policy, an attempt is made to secure
a reservation for each media stream, the audio stream and the video
steam at block 506. In an embodiment, call agent 100 may determine
whether the Reservation handling policy is a no reservation policy
before determining whether the Reservation handling policy is
mandatory or optional. At block 508, a decision is made whether a
reservation for the audio stream has been secured. If the audio
stream has not secured a reservation, a reservation failure option
for the audio stream is exercised at block 510. Reservation failure
options for the audio stream may include releasing the call,
re-routing the call through a PSTN, or any other suitable
reservation failure option for the audio stream.
[0055] Securing a reservation for the audio stream at block 508
allows the method to proceed to block 512 where call agent 100
connects the call and endpoints 106 begin exchanging audio. At
decision block 514, it is determined whether the video stream has
secured a reservation. If the video stream has not secured a
reservation, a reservation failure option is exercised for the
video stream at block 516. The reservation failure options for the
video stream may include releasing the video stream or any other
suitable reservation failure option for the video stream. If the
video stream does secure a reservation, endpoints 106 exchange
video and continue exchanging audio during the call at block 518.
The call between endpoint 106 may terminate at block 520 and the
method subsequently ends.
[0056] If a reservation is not obtained at block 508, for an audio
optional Reservation handling policy, the call is connected at a
lower QoS at block 522. The check for a video stream reservation is
made at block 514. If a video stream reservation is not made, most
likely since an audio stream reservation was not obtained, audio is
continued to be exchanged between endpoints 106 at block 524. It is
possible to provide video at this point with a lower QoS if so
desired at block 524. The retry procedure discussed above may also
be incorporated into this flowchart as desired whenever an audio or
video reservation is not secured.
[0057] Bandwidth may be preserved in a RSVP environment. Preserving
bandwidth is initiated when a feature is implemented during media
exchange between endpoints 106. The feature may include placing an
endpoint 106 on hold, invoking a supplementary service during the
media exchange, conferencing among three parties, or any suitable
feature to trigger preserving bandwidth. A supplementary service
causes the parties to change during a call.
[0058] FIG. 6A is a flowchart illustrating an embodiment of a
method for preserving bandwidth when an endpoint 106 is placed on
hold. FIG. 6B is an example message flow for the on hold situation.
Endpoints 106a and 106d exchange media using a RSVP reservation in
block 600 that has been established as discussed above. At decision
block 602, it is determined whether endpoint 106d is placed on hold
by endpoint 106a. If endpoint 106d has not been placed on hold, the
media exchange continues between endpoints 106a and 106d using the
RSVP reservation. If endpoint 106d has been placed on hold by
endpoint 106a, the reservation that endpoints 106a and 106d used is
preserved at block 604. Preserving the reservation preserves the
bandwidth that endpoints 106a and 106d used to exchange media.
[0059] A Music-on-Hold (MOH) server is used during on hold
situations. At block 605, a determination is made as to whether a
RSVP reservation is need between the MOH server and on hold
endpoint 106d. If not, the MOH server sends media to on hold
endpoint 106d at block 607 when endpoint 106a places endpoint 106d
on hold. If a RSVP reservation is needed, a reservation is obtained
at block 606 before media is exchanged at block 607. The MOH server
may be in the path of QoS Agent 104a, 104b, or it may be remotely
located. If MOH server is co-located with on hold endpoint 106d and
QoS agent 104b, the preserved RSVP reservation is maintained and
not used between the MOH server and on hold endpoint 106d. If the
MOH server is co-located with endpoint 106a that placed endpoint
106d on hold, the preserved RSVP reservation may be reused to
connect the MOH server with on hold endpoint 106d and reused again
when endpoint 106a takes endpoint 106d off hold. If the MOH server
is remotely located from both endpoint 106a and endpoint 106d, a
new RSVP reservation may need to be established between on hold
endpoint 106d and the MOH server. Decision block 608 determines
whether on hold endpoint 106d is taken off hold by endpoint 106a.
If on hold endpoint 106d remains on hold, the MOH server continues
sending media to on hold endpoint 106d. If on hold endpoint 106d is
taken off hold at decision block 608, the media exchange between on
hold endpoint 106d and endpoint 106a resumes at block 610, using
the preserved RSVP reservation. Therefore, the original RSVP
reservation can be reused between holding endpoint 106a and holder
endpoint 106d after the hold state ends. The original RSVP
reservation may also be used when the MOH server is co-located with
endpoint 106a and QoS Agent 104a when placing endpoint 106d on
hold. The call eventually terminates at block 612 and the method
subsequently ends. If reservations between on hold endpoint 106d
and the MOH server cannot be obtained, tone on hold will be applied
to on hold endpoint 106d.
[0060] FIG. 7A is a flowchart 70 illustrating another embodiment of
a method for preserving bandwidth when a call is transferred to a
new endpoint 106. FIG. 7B is an example message flow for the call
transfer situation. Endpoints 106a and 106d exchange media using a
RSVP reservation in block 700 that has been established as
discussed above. A supplementary service may be invoked during the
media exchange. The supplementary service may include transferring
a call between endpoints 106, forwarding a call to another endpoint
106, and any suitable supplementary service to enhance the media
exchange. At decision block 702 in the illustrated embodiment, it
is determined whether the call is to be transferred to another
endpoint 106c. If the call is not to be transferred, the media
exchange continues between endpoints 106a and 106d using the RSVP
reservation. If endpoint 106a is transferring the call, the
reservation used between endpoints 106a and 106d is preserved at
block 704. Preserving the reservation preserves the bandwidth that
endpoints 106a and 106d used to exchange media. Upon endpoint 106a
initiating a transfer, endpoint 106d may be placed on hold as
outlined above.
[0061] At decision block 706, it is determined whether transferred
endpoint 106d is in the same location as endpoint 106c receiving
the transferred call. If transferred endpoint 106d and receiving
endpoint 106c are in the same location, transferred endpoint 106d
and receiving endpoint 106c exchange media at block 708 either
using a new reservation determined at block 707 or without using a
reservation at all and the preserved RSVP reservation is released.
The call eventually terminates at block 712. If the receiving
endpoint is in a different location from both endpoints 106a and
106b at block 709, process also flows to block 707. If receiving
endpoint 106c is in the same location as endpoint 106a, the
preserved RSVP reservation from the original media exchange between
transferred endpoint 106d and endpoint 106a may be reused. At block
710, the non-co-located endpoints 106 exchange media. The call
eventually terminates at block 712 and the method subsequently
ends.
[0062] The method may apply when any suitable supplementary service
is invoked. For example, a conference call may re-use a preserved
reservation if the conference bridge is in the same location as the
endpoint beginning the conference call. Additionally, steps may be
performed in any suitable order without departing from the scope of
the invention.
[0063] FIG. 8 is a flowchart 80 illustrating another embodiment of
a method for preserving bandwidth upon establishing of a conference
call. Endpoint 106a establishes the exchange of media with endpoint
106d at block 800. Assuming reservations were obtained for the
media exchange between endpoints 106a and 106d, these reservations
will be preserved when endpoint 106a attempts to initiate a
conference call among endpoint 106d and another endpoint 106f. Upon
initiation of a conference call at block 802, the media exchange
between endpoints 106a and 106d is disconnected and the reservation
is preserved at block 804. This event essentially places endpoint
106d in an on hold state, the establishment of such a state being
previously discussed above. Endpoint 106a will then establish a
connection with endpoint 106f at block 806, using reservations as
needed and as discussed above. Since endpoint 106f is in the same
location as endpoint 106d, it may be possible to reuse the
preserved reservations for the connection between endpoints 106a
and 106d.
[0064] Upon establishing a connection with endpoint 106f, endpoint
106a initiates the conferencing capability so that each of
endpoints 106a, 106d, and 106f can exchange media with each other.
Endpoint 106d will be removed from its on hold status. Upon
initiating the conference call, each of endpoints 106a, 106d, and
106f are redirected to a conference bridge at block 808 so that
media exchange can occur. The reservations between endpoints 106a
and 106f will be preserved at block 810. Call agent 100, through
QoS agents 104a and 104b, will perform RSVP reservations
individually for each of endpoints 106a, 106d, and 106f with the
conference bridge. Preserved Reservations may be reused if the
conference bridge is co-located with either QoS agents 104a or
104b. If endpoint 106d leaves the conference call at block 812,
call agent 100 may redirect endpoints 106a and 106f off of the
conference bridge at block 814 and reestablish the preserved
reservations between endpoints 106a and 106f for a direct exchange
of media. Call agent 100 will release the reservations between
endpoints 106a and 106d and endpoints 106a and 106f at block 816
upon termination in each reservation by one of the endpoints
106.
[0065] FIG. 9 is a flowchart 90 illustrating another embodiment of
a method for preserving bandwidth for a call forwarding
implementation. Call agent 100 may support at least three types of
call forwarding--call forward all, call forward no answer, and call
forward busy. An example forwarding situation when endpoint 106a
calls endpoint 106d at block 900 and endpoint 106d has its calls
possibly forwarded to endpoint 106f at block 902. If call
forwarding is not enabled, then media is exchanged between
endpoints 106a and 106d at block 904. For a call forward all
operation, a call from endpoint 106a to endpoint 106d will
immediately be extended to endpoint 106f. Call agent 100 needs to
only establish RSVP reservations between QoS agents 104a and 104b
at block 908 for an exchange of media between endpoints 106a and
106f at block 910. For a call forward no answer operation, call
agent 100 establishes reservations between endpoints 106a and 106d
at block 912. A timer is initiated and the call will be extended to
endpoint 106f upon expiration of the timer if endpoint 106d does
not answer at block 914. Before forwarding the call to endpoint
106f, call agent will release the reservations associated with
endpoint 106d and establish reservations associated with endpoints
106a and 106f. Call agent 100 may reuse the reservations associated
with endpoint 106d for endpoint 106f if they are co-located. For a
call forward busy operation, no timer is used and forwarding will
begin immediately upon determining that endpoint 106d is off hook
at block 916. If endpoint 106d should answer, then media is
exchanged between endpoints 106a and 106d at block 916. The call
eventually terminates at block 918.
[0066] FIG. 10A is a message flow illustrating a shared line
implementation. In this scenario, endpoints 106d and 106f share the
same directory number. When endpoint 106a desires to establish a
connection through this directory number, RSVP reservations are
established between endpoint 106a and both endpoints 106d and 106f.
If endpoints 106d and 106f are in the same location, a single QoS
agent 104b is used in establishing the RSVP reservations that are
shared for endpoints 106d and 106f. If endpoints 106d and 106f are
in different locations, separate reservations are established
through QoS agent 104b for endpoint 106d and a different QoS agent
for endpoint 106f. Upon establishing, or concurrently with
establishing, the reservations between endpoint 106a and endpoints
106d and 106f, ring signals are provided to both endpoints 106d and
106f. In the example shown, endpoint 106d goes off hook first and
media is exchanged between endpoint 106a and 106d. Any reservations
established with endpoint 106f will then be torn down.
[0067] FIG. 10B is a message flow illustrating an on hold event in
a shared line implementation. In this scenario, endpoint 106a
places endpoint 106b on hold as previously discussed and the
reservations are preserved. However, being a shared line, endpoint
106f resumes the call with endpoint 106a. If endpoint 106f is
co-located with endpoint 106d, then the preserved reservations can
be reused for the endpoint 106a to endpoint 106f connection. If
endpoint 106f is in a different location than endpoint 106d, then
the preserved reservations are released and new reservations for
the endpoint 106a to endpoint 106f connections are established in a
manner as previously described above. Call agent 100 allocates a
new QoS agent for endpoint 106f and the connection with endpoint
106d is torn down.
[0068] FIG. 11 is a flowchart 1100 illustrating an embodiment for
activating video media during a connected call. Endpoints 106
exchange audio media between each other in block 1101. Call agent
100 dynamically determines whether video has been activated at
decision block 1102. If video is not activated, caller endpoint
106a and callee endpoint 106d continue to exchange audio media. If
video is activated, call agent 100 determines the video capability
of callee endpoint 106d at block 1104. Decision block 1106
determines whether callee endpoint 106d is video enabled. If callee
endpoint 106d does not have video capability, call agent 100 does
not add video media to the media stream and the exchange of audio
media between caller endpoint 106a and callee endpoint 106d
continues. If callee endpoint 106d is video enabled, video media is
added to the call with a RSVP reservation at block 1110. Endpoints
106 now may exchange audio and video media at block 1112. While
exchanging audio media, video media, or both, the call terminates
at block 1114 and the method subsequently ends.
[0069] In another embodiment, endpoints 106 may be exchanging video
media in addition to the audio media. In this embodiment, the video
media is deactivated from the call if receiving endpoint 106c is
not video enabled. For example, callee endpoint 106d may transfer
the call from caller endpoint 106a to receiving endpoint 106c.
While caller endpoint 106a and callee endpoint 106d exchanged video
media, receiving endpoint 106c may not have video capability. Call
agent 100 dynamically detects the video capability of receiving
endpoint 106c, instructs QoS agent 104 to release the reservation
resources for the video media, and initiates the RSVP reservation's
release.
[0070] As discussed above, the RSVP mechanism is synchronized with
call signaling in order to, when appropriate, delay or hold the
ring alert to the called party until the reservation is successful
under mandatory conditions. Call agent 100 also has the ability to
fail or re-route the call on a reservation failure as appropriate,
including providing proper notification to the end user. For
example, call agent 100 provides at least the same notification as
other Call Admission Control types about the reservation failure to
an end user in a mandatory situation. For an IP phone, call agent
100 may display "not enough bandwidth" and provide a fast busy tone
to the end user. The fast busy tone may be replaced by a voice
prompt indicating the failure condition. In an optional situation,
the call can still proceed even with a RSVP failure during call
setup. The call is then likely to begin with poor voice quality.
However, this poor quality state may be transient and the automatic
reservation retry capability may succeed during the call to provide
adequate bandwidth. Call agent 100 may initially inform the end
user that impaired audio may be experienced for the call. Once a
reservation is obtained, call agent 100 may inform the end user
that normal network conditions have been achieved and good audio
quality has been restored.
[0071] QoS agents 104 act as a proxy for call agent 100 in
implementing the RSVP mechanism. QoS agents 104 work independently
of the endpoints 106 and provide appropriate RSVP control messaging
to call agent 100. In this manner, endpoints 106 may be of various
types of devices implementing different protocols as shown above.
QoS agents 104 coordinates with call agent 100 to synchronize the
RSVP signaling with the call signaling. The functionality of QoS
agents may be contained in a single entity or distributed
throughout the network. The QoS agent functionality may be placed
into call agent 100 or locations 102 in whole or in part. Through
the use of QoS agents 104, the RSVP mechanism may be separated and
apart from the media path between endpoints 106.
[0072] Modifications, additions, or omissions may be made to any
flowchart or message flow described above without departing from
the scope of the invention. Additionally, steps may be performed in
any suitable order without departing from the scope of the
invention.
[0073] Certain embodiments of the invention may provide one or more
technical advantages. A technical advantage of one embodiment may
be that RSVP can be used in a system without having to touch every
endpoint. The endpoints may support different protocols and
interact with RSVP within the same system. Furthermore, endpoints
that are RSVP-enabled can communicate with non-RSVP enabled
endpoints. Another technical advantage of another embodiment may be
that calls do not fail if a RSVP reservation is not secured with
the initial attempt. Allowing calls to proceed without a RSVP
reservation prevents complete call failure. Yet another technical
advantage of an embodiment may be that calls may gain a reservation
during a call, which improves the QoS, or may restore a reservation
that fails mid-call, which also improves a call's QoS.
[0074] While this disclosure has been described in terms of certain
embodiments and generally associated methods, alterations and
permutations of the embodiments and methods will be apparent to
those skilled in the art. Accordingly, the above description of
example embodiments does not constrain this disclosure. Other
changes, substitutions, and alterations are also possible without
departing from the spirit and scope of this disclosure.
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