CA2493501A1 - Modem relay aggregator device - Google Patents

Modem relay aggregator device Download PDF

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Publication number
CA2493501A1
CA2493501A1 CA002493501A CA2493501A CA2493501A1 CA 2493501 A1 CA2493501 A1 CA 2493501A1 CA 002493501 A CA002493501 A CA 002493501A CA 2493501 A CA2493501 A CA 2493501A CA 2493501 A1 CA2493501 A1 CA 2493501A1
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CA
Canada
Prior art keywords
modem
over network
aggregator
signals
control messages
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002493501A
Other languages
French (fr)
Inventor
Scott Anthony Boynton
Alex Urquizo
Vincent Todd Grove
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cisco Technology Inc
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of CA2493501A1 publication Critical patent/CA2493501A1/en
Abandoned legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/28Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/2854Wide area networks, e.g. public data networks
    • H04L12/2856Access arrangements, e.g. Internet access
    • H04L12/2869Operational details of access network equipments
    • H04L12/2898Subscriber equipments

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Telephonic Communication Services (AREA)
  • Communication Control (AREA)
  • Maintenance And Management Of Digital Transmission (AREA)

Abstract

A network device is disclosed. The network device has at least one port to receive modem over network signals. A router routes data associated with the modem over network signals received from an aggregator. The aggregator uncompresses the modem over network signals and sends the data associated wi th the signals to the router directly without relying upon a digital signal processor.

Description

MODEM RELAY AGGREGATOR DEVICE
BACKGROUND
1. Field This disclosure relates to modem relay, more particularly to modem relay devices that combine egress gateways and remote access servers.
2. Background l0 The International Telecommunications Union (ITU) is in the process of approving a new standard for modem sessions over packet networks, referred to as modem over Internet Protocol (V.MoIP). It must be noted that this standard may actually apply to all packet networks, not just IP.
Modem relay terminates the physical layer and link layer error correction/detection protocol at the ingress gateway and may send compressed data over a packet network to an egress gateway. The first leg of the call occurs between the modem and the ingress gateway, where the modem signals are converted to packets. The second leg of the call sends the packets across the data network to the egress gateway. The final leg of the call, between the egress gateway and the remote 2o access server, remodulates the packet data back into modem signals and sends the modem signals to the remote access server.
Typically, the egress gateway terminates the physical Iayer at the gateway and has a processor that handles the remodulation and connection between the egress gateway and the remote access server.
2s SiTMMARY
One embodiment of the invention is a network device having at least one port to receive modem over network signals. A router routes data associated with the modem over network signals received from an aggregator. The aggregator uncompresses the modem over network signals and send the data associated with the signals to the router directly.
Ingress gateways communicating with the network device negotiate with the client modem without waiting for modem response tones from the network device.
The ingress gateway has either already identified the network address to which the modem is trying to connect to be a such a network device, or it is informed of that during call setup. The ingress gateway then routes data associated with the call to the network device.
to The network device receives signals indicating that there is an incoming modem over data network call and communicates with the ingress gateway. The network device then routes the data as if it were a remote access server.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be best understood by reading the disclosure with reference 15 to the drawings, wherein:
Figure 1 shows an embodiment of a network employing modem relay, in accordance with the prior art.
Figure 2 shows an embodiment of a network employing modem relay, in accordance with the prior art.
2o Figure 3 shows an embodiment of a network employing modem relay, in accordance with embodiments of the invention.
Figure 4 shows a flow chart of one embodiment of a method to perform modem relay, in accordance with embodiments of the invention.
Figure 5 shows a flow chart of one embodiment of a method to perform 25 modem relay, in accordance with embodiments of the invention.

Figure 6 shows a block diagram of a network device capable of modem relay aggregation, in accordance with embodiments of the invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
An example of a network capable of transmitting modem signals over a network in accordance with the prior art is shown in Figure 1. Client modem 10 dials the ingress gateway 12. The ingress gateway 12 then connects to the egress gateway 16, which dials the remote access server (RAS) 18 based on the information provided by the ingress gateway. Both gateways proceed to negotiate their capabilities during call setup using out-band signaling such as H.323, session initiation protocol (SIP), or 1 o media gateway control protocol (MGCP). Once the gateways' capabilities are known, the modems proceed to negotiate. Usually, the answer modem (RAS) sends an Answer tone to start the modem physical layer train-up.
The ingress gateway 12 accepts the modem tone signals and converts them to packet data and transmits them across the network 14 to the egress gateway 16.
I5 Egress gateway 16 then reconverts the data back into modem tones via remodulation and transmits those tones to the remote access server (RAS) 18. The process is then performed in the reverse direction to facilitate call setup and negotiation between the modem 10 and the remote access server (RAS) 18.
In the ITLT standard for Modem Relay, currently under development, the 2o physical layer and link layer error correction/detection protocol are terminated at the ingress gateway. The egress gateway may perform error correctionldetection and remodulate the data into the modulated tones necessary for communication with the RAS 18.
In an alternative embodiment of current implementation in accordance with 25 the prior art, the egress gateway and the remote access server are combined into one device referred to as a modem relay aggregator (MR.A) 20. The MRA 20 has a digital signal processor 22 that generates and provides the modem response tones necessary to communicate with the client modem 10. However, it is possible to provide an MRA that does not require a digital signal processor, or any modem physical layer negotiation with the client modem.
As can be seen in Figure 3, the client modem 30 transmits modem tones to the ingress gateway 32, which converts those tones to packet data and transmits it across the network 34 to the MRA 36. With the deployment of an MRA, there can be an exchange of information during the call setup phase in which the ingress gateway to determines that the remote access server to which the user wants to gain access is actually an MRA. Alternatively, the ingress gateway may already have the existence of the MRA associated with the address of the RAS before receiving any calls from modems trying to connect to that address.
In either case, if the ingress gateway has the information that the end of the 15 connection is an MRA, the ingress gateway 32 can localize the modem negotiation and negotiate with the client modem 30 without receiving any modem response tones from the MRA 36. Once the modem negotiation is completed, the ingress gateway would route the information to the MRA 36 via the network 34 as if the MRA
were now the RAS to which the client modern was trying to connect. The MRA would 2o then route the data coming from the client modem, functioning as an RAS.
For purposes of the discussion here, this data will be referred to as 'data associated with the modem over network call,' as the data being routed by the MRA in the capacity of an RAS is coming from a client modem that 'thinks' it is connected to a RAS as in the prior art implementation such as that of Figure 1.

In this manner, there is no need for the MRA to generate modem response tones, and therefore no need for a DSP in the MRA. In addition to this simplification of the device, the MRA functioning without the modem response process eliminates any delays or packet drops that may occur during call discrimination or initial modem training. This may also provide faster modem connections, as there is only one modem connection in the circuit established between the modem 30 and the MR.A
36.
One embodiment of a process to connect a call at the MRA is shown in flowchart form in Figure 4. The MRA receives modem over network signals in a control signal exchange with the ingress gateway at 40. No response to these signals 1 o may be necessary, as there is no need to generate the modem response tones. The modem over network signals may be the initial signals for call setup between the MRA and the client modem, or they may be other signals that initiate a call.
If the ingress gateway does not already understand that the egress gateway/RAS combination has been replaced by an MRA, or that the MR.A will not 15 be providing modem response tones, the MRA may send an identification signal at 42 that informs the ingress gateway of the nature of the MRA. This will then cause the ingress gateway to perform the modem negotiation without waiting for modem response tones from the MRA or the R.AS. Once the call setup has been completed, the ingress gateway and the MRA may optionally negotiate call parameters such as 20 optimal data compression parameters at 44. The MRA then begins routing data from the client modem, functioning in the capacity of a R.AS, at 46.
One embodiment of a process to connect a call using an MRA from the ingress gateway is shown in Figure 4. The ingress gateway receives a call from a client modem at 50. As mentioned before, the ingress gateway may already realize that the 25 RAS to which the client modem is connecting is actually an MRA.
Alternatively, the ingress gateway may be informed of that during call setup. In the first scenario, the ingress gateway may perform an optional process of determining the appropriate MRA. to which the call should be routed at 52. This may be implemented using DhlIS
(dialed number identification service) in which the ingress gateway associates the dialed number with one of several MRAs. In the second scenario, the ingress gateway may need to determine that the egress gateway is an MRA, as shown at 54.
However, neither of these two processes is necessary. The ingress gateway may already realize that the RAS to which the modem is attempting to connect is an MRA and may start modem negotiation at 56, without any determination of an to appropriate MRA. Once the modem negotiation is complete, the ingress gateway routes the data associated with the call to the MRA at 58. The MRA would then function as the RAS and route the data accordingly. All of this is done without the use or need for a DSP, which will be referred to as routing the data directly.
The DSP can be replaced by a less expensive solution such as an FPGA (field 15 programmable gate array) or a general-purpose processor such as a RISC
(reduced instruction set) processor. The advantage of the FPGA is that it could implement in hardware the well-defined algorithms, which perform data compression such as V.42bis, and V.44, and create a solution that is faster than a DSP, supports more sessions and is Less expensive. The advantage of the general-purpose processor such 2o as a RISC processor is that it is a less expensive method to terminate the PPP protocol - stack.
As can be seen in Figure 6, one embodiment of an MRA is shown. The MRA
36 includes at least one port 60 through which the modem over data networks signals are received. As shown in Figure 6, the modem over data networks are specific to 25 Internet Protocol (IP) and may be either Voice over IP (VoIP) or Modem over IP

(MoIP). However, application of this invention is not restricted to IP, as it may be applied to any packet network. Similarly, both of these specific types of calls will be included in the description of 'modem over data network' call.
When the call is first brought up, the channel is considered a VoIP (Voice over IP) call. The channel is in Audio mode and it uses RTP (Real Time Transport Protocol). The V.MoIP standaxd specifies two methods to transport modem signals across the packet network. One is Modem Relay that uses a different transport protocol called SPRT (Simple Packet Relay Transport). Therefore, Modem Relay has a different protocol stack using SPRT even though it uses the same VoIP
channel. The to second method is call VBD (voice band data) where the channel uses RTP and modem signals are transported across the packet network using a codec suitable for modem signals such as under 6.711. So VBD is similar to Audio Mode. However, certain special voice setting need to be used in order to transport modem signals reliably, such as using a fixed fitter buffer. In essence, Modem Relay uses the same 15 infrastructure as a VoIP call, but uses a different transport protocol optimally designed to carry modem signals across a packet network.
In the example where a VoIP channel is used to carry on signals in the VBD
mode the modem signals are not terminated at the gateways. The gateways transport the modem signals as they are across the VoIP channel using RTP protocol. If 2o Modem Relay is used the physical and Link Layer error corrections are terminated at the gateway. The gateway then uses the protocol SPRT to carry on the modem data across the packet network.
A second port 68 may be used for communication with the network for routing the data associated with the modem over data network call. In actuality, it may be the 25 same port, but for ease of understanding, they are shown as two separate ports here.

The aggregator 64 is operable to receive the modem over network signals and terminate the modem or voice call, and then pass the data associated with that call to the router 66 directly, without any modem negotiation. The muter then routes the data accordingly. In terminating the call, the aggregator does not responds to the modem signals, as would an MRA with a DSP, but instead may send the signal that indicates that the ingress gateway should handle that activity, if necessary.
During call setup, the aggregator 64 may communicate with the ingress gateway to exchange control signals, beyond any signals sent to identify the device as an MRA. These may be performed using in-band signaling, H.323 or H.248 Megaco to format messages, media gateway control protocol (MGCP) messages, or session initiation protocol (SIP) messages, as examples. The aggregator may be a field-programmable gate array (FPGA), or an application specific integrated circuit (ASIC), as examples.
The elimination of the DSP at the MRA provides simplified requirements for 15 the network device hardware, which may in turn lead to lower costs. As mentioned earlier, the elimination of the modem negotiation signals required by current implementations of the MRA eliminates the possibility of delays and packet drops during call setup, making the connection complete faster.
Thus, although there has been described to this point a particular embodiment 2o for a method and apparatus for a modem relay aggregator, it is not intended that such specific references be considered as limitations upon the scope of this invention except in-so-far as set forth in the following claims.

Claims (21)

WHAT IS CLAIMED IS:
1. A network device, comprising:
a port to receive modem over network signals;
a muter to route data associated with the modem over network signals; and an aggregator to uncompress the modem over network signals and send the data associated with the signals to the router directly.
2. The network device of claim 1, wherein the aggregator further comprises a field programmable gate array.
3. The network device of claim 1, wherein the aggregator further comprises an application specific integrated circuit.
4. The network device of claim 1, wherein the device further comprises a second port to route the signals from the router.
5. The network device of claim 1, wherein the aggregator is further to deframe point-to-point protocol frames received as data associated with the modem over network signals.
6. A method of providing modem relay, the method comprising:
receiving modem over network signals from an ingress gateway;
sending an identification signal to the ingress gateway notifying the ingress gateway that modem negotiation is unnecessary; and routing data associated with the modem over network signals directly.
7. The method of claim 6, wherein the method further comprises negotiating optimal data compression with the ingress gateway.
8. The method of claim 6, wherein the modem over network signals further comprise control messages using in-band signaling.
9. The method of claim 6, wherein the modem over network signals further comprise control messages using H.323.
10. The method of claim 6, wherein the modem over network signals further comprise control messages using session initiation protocol.
11. The method of claim 6, wherein the modem over network signals further comprise control messages using media gateway control protocol.
12. The method of claim 6, wherein the modem over network signals further comprise control messages using H.248 Megaco.
13. The method of claim 6, wherein the method further comprises using dialed number identification service to route the call to a network device.
14. A method of providing modem connection, the method comprising:
receiving a call from a client modem;
performing modem negotiation with a client modem without receiving any modem tone from a modem relay aggregator; and transmitting data to the egress gateway.
15. The method of claim 14, wherein the method further comprises using dialed number identification service to identify an appropriate modem relay aggregator.
16. The method of claim 14, wherein the method further comprises determining that the terminating device is a modem relay aggregator prior to performing modem negotiation.
17. The method of claim 16, wherein determining that the terminating device is a modem relay aggregator further comprises exchanging control messages using in-band signaling.
18. The method of claim 16, wherein determining that the terminating device is a modem relay aggregator further comprises exchanging control messages using session initiation protocol.
19. The method of claim 16, wherein determining that the terminating device is a modem relay aggregator further comprises exchanging control messages using H.323.
20. The method of claim 16, wherein determining that the terminating device is a modem relay aggregator further comprises exchanging control messages using media gateway control protocol.
21. The method of claim 16, wherein the modem over network signals further comprise control messages using H.248 Megaco.
CA002493501A 2002-07-30 2003-07-30 Modem relay aggregator device Abandoned CA2493501A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US10/209,052 2002-07-30
US10/209,052 US7359369B2 (en) 2002-07-30 2002-07-30 Modem relay aggregator device
PCT/US2003/024085 WO2004012398A1 (en) 2002-07-30 2003-07-30 Modem relay aggregator device

Publications (1)

Publication Number Publication Date
CA2493501A1 true CA2493501A1 (en) 2004-02-05

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Application Number Title Priority Date Filing Date
CA002493501A Abandoned CA2493501A1 (en) 2002-07-30 2003-07-30 Modem relay aggregator device

Country Status (8)

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US (1) US7359369B2 (en)
EP (1) EP1525715B1 (en)
CN (1) CN100505656C (en)
AT (1) ATE381826T1 (en)
AU (1) AU2003268042B2 (en)
CA (1) CA2493501A1 (en)
DE (1) DE60318209T2 (en)
WO (1) WO2004012398A1 (en)

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Also Published As

Publication number Publication date
ATE381826T1 (en) 2008-01-15
AU2003268042A1 (en) 2004-02-16
CN100505656C (en) 2009-06-24
WO2004012398A1 (en) 2004-02-05
US20040022241A1 (en) 2004-02-05
US7359369B2 (en) 2008-04-15
EP1525715A1 (en) 2005-04-27
DE60318209T2 (en) 2008-12-04
CN1672366A (en) 2005-09-21
AU2003268042B2 (en) 2009-03-05
EP1525715B1 (en) 2007-12-19
DE60318209D1 (en) 2008-01-31

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Legal Events

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EEER Examination request
FZDE Discontinued