Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
1999-07-01
2003-05-27
Kizou, Hassan (Department: 2662)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S235000, C370S392000, C370S395210
Reexamination Certificate
active
06570851
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to communication systems and methods of communication in which packet data transmissions between source nodes and destination nodes have a controlled per hop processing.
2. Description of the Prior Art
FIG. 1
illustrates a diagram of a prior art communication system
10
for transmitting packet data transmissions between a plurality of source nodes
12
A-N to a plurality of destination nodes
14
1-N. Each destination node
14
may be any type of receiving device, such as a cellular or asynchronous transfer mode (ATM) receiver, etc. Each source node
12
, which may be any type of data originating device, originates packet data transmissions each containing data packets which may be transmitted with various data protocols such as, but not limited to, TCP/IP. Individual packet data transmissions from the source nodes
12
are transmitted to one or more routers
16
which are typically under the jurisdiction of an internet service provider (ISP). The data packets are outputted from the routers
16
to a packet data network
18
which typically is an IP network. The packet data network
18
provides connectivity of the inputted data packets received from the routers
16
to one or more routers
20
. The routers
20
are also typically under the jurisdiction of an ISP. The last router
20
, in a non-wireless embodiment, transmits the packet data transmissions to the destination node
14
via a communication link
22
such as, but not limited to, a relatively low bandwidth telephone link and therefore, a limited data transmission capacity. Alternatively, the last router (n)
20
in a wireless application outputs the packet data transmissions to a base station
24
which transmits the packet data transmission via a wireless link
26
, typically of relatively low bandwidth, to the destination node
14
. All of the component parts of the communication system
10
are well known and in wide spread usage today.
Traditionally, ISPs have provided all customers with the same level of performance (best-effort service). Service differentiation has been limited to the pricing structure (individual vs. business rates) or the connectivity type (dial-up access vs. leased line, etc.). However, with the growth of the internet in recent years, a temporal scarcity of network capacity can arise which compromises performance of traditional mission critical applications. Additionally, new applications have emerged which demand improved service quality. As a result, ISPs are finding it necessary to offer customers alternative levels of service. As well as meeting new customer expectations, alternative levels of service allow ISPs to improve revenue through premium pricing and competitive differentiation of service offerings, which in turn can fund the necessary expansion of the network.
The internet engineering task force (IETF) has proposed a differentiated services architecture in which IP packets are labelled with a DS field by a source or other node, such as the source nodes
12
or other nodes in FIG.
1
. The IETF differentiated services scheme is described in the February 1999 draft—IETF-Diffserv-Framework-02.TXT which document is incorporated herein by reference in its entirety.
The differentiated services architecture is a one-way network to destination node protocol offering a framework within which ISPs can offer each customer a range of network services which are differentiated on the basis of performance in addition to pricing tiers used in the past. Customers request a specific performance level in a packet by packet basis, by marking a differentiated services (DS) field of each packet with a specific value. The DS field contains a differentiated services code point (DSCP). The DSCP is not a priority and is an abstract number which a controlling node, such as a router, maps to a specific per hop behavior (PHB) which in turn relates to quality of service (QOS) or more generically to the treatment of a packet relative to other packets by the controlling node (router) at the time. The PHB is meaningful in relation to other PHBs in the same class (or group) and to the service policy implemented by the controlling node (router). The DS field structure is 8 bits in length with 6 bits (
0
-
5
) being allocated to encoding the DSCP and 2 bits (
6
-
7
) encoding the quantity CU which is currently unused. The DSCP value selects the PHB processing that a packet receives at each node. The DSCP may be any value with most values not being standardized. The DS field structure is called a TOS field in the IPv4 header and a Class field in the IPv6 header. Typically, the customer and the ISP negotiate a profile (policing profile) describing the rate at which traffic can be submitted at each service level. Packets in excess of this profile may not be allotted the service level requested. A salient feature of differentiated services is scalability allowing deployment in very large networks. The scalability is achieved by forcing as much complexity out of the core of the network into the boundary devices which processes lower volumes of traffic and lesser numbers of flows, and offering services for aggregate traffic rather than on a per-micro-flow basis. The differentiated services architecture may be utilized in a communication system such as the prior art of FIG.
1
.
Certain deficiencies exist with the current differentiated services architecture. Slow access links (wireless or telephone modem) present the sender-oriented differential services architecture with serious drawbacks as a consequence of only the source, such as the source nodes
12
of the prior art diagram of
FIG. 1
, being in control of the per hop behavior of the packet data transmissions which are received by the destination nodes
14
as the result of only the source nodes typically specifying the value of the aforementioned DSCP field.
The prevalence of low bandwidth access links, such as links
22
and
26
in the prior art of
FIG. 1
, is a network limitation which will not disappear in the near future. Continued usage of dial up modems with plain old telephone service and a large growth in the number of wireless mobile phones acting as IP hosts will increase the number of low bandwidth access links.
Different types of problems result from low bandwidth access links which severely interfere with the destination nodes
14
of
FIG. 1
properly receiving data under the differentiated services architecture as a consequence of the PHB being solely dictated by the source nodes
12
or the upstream network. Source node control in an organization's access link can create problems between a company LAN and an ISP. A company may have a 64K bit/s incoming link from an ISP. When a company worker is connected to the world wide web and connects to an advertisement video, the high quality of service specified by the video at source node
12
will consume over 100K bit/s as a consequence of the DSCP value being marked with the highest value. As a result, a single advertisement video utilizes the whole access link capacity preventing all other activity with the link. Another example is when the user of a destination node is having a IP-telephone conversation. If the person receiving the IP call asks the user to look at a web page, the user's request for the web page consumes the available bandwidth as a result of it originating from a commercial web server, providing prompt responses in which all traffic is sent with the highest DSCP value. As a result, the IP-phone conversation can be severely degraded by the connectivity of the web page to the user. An additional example is when a multicast video is sent to a group of receivers in which the video is marked with a DSCP value representing a high priority. Receipt of this video will totally consume limited bandwidth links, such as links
22
and
26
in
FIG. 1
, connecting routers to destination nodes.
The current differentiated services architecture focus is totally on the network with the sender controlling the pe
Koskelainen Petri
Rajahalme Jarno
Antonelli Terry Stout & Kraus LLP
Kizou Hassan
Ly Anh-Vu H
Nokia Telecommunications Oy
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