Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-11-03
2002-12-03
Jung, Min (Department: 2663)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C709S227000
Reexamination Certificate
active
06490289
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of computer networks. More particularly, the present invention relates to managing multiple network connections from a single PPP link while performing network address translation.
2. The Background
The Point-to-Point protocol (PPP) is a data link protocol that provides dial up access over analog or digital transmission lines. PPP provides many advanced features, including error detection, support of multiple protocols, negotiation of IP addresses at connection time, and authentication. There are three main features of PPP. The first is that it provides a framing method to delineate the end of one frame and the beginning of the next one, in order to handle error detection. The second is a link control protocol for bringing lines up, testing them, negotiating options, and bringing them down again when they are no longer needed. This is known as the Link Control Protocol (LCP). The third is a way to negotiate network layer options in a way independent of the network layer protocol to be used. Thus, the method chosen may have a different Network Control Protocol (NCP) for each network layer supported.
PPP is commonly used as the data link protocol between a user and an Internet Service Provider (ISP) or access point. This is usually accomplished through the following method. The personal computer of the user is instructed to call the ISP through a modem. After the ISP's modem receives the call and establishes a physical connection, the personal computer sends a series of LCP packets in the payload field of one or more PPP frames. These packets, and their responses, comprise the negotiation of the session, and set the PPP parameters to be used during the session.
Once the negotiation is complete, a series of NCP packets are sent to configure the network layer. Typically, the personal computer wants to run a TCP/IP protocol stack, so it needs an IP address. The NCP for IP may then be used to assign an IP address to the user (dynamic assignment of IP addresses is now common for dial-up users). At this point, the personal computer has become an Internet host and may send and receive IP packets, just as a hardwired host could. When the user has finished, NCP is used to tear down the network layer connection and free the IP address. The LCP is then used to shut down the data link layer connection. Finally, the personal computer hangs up the modem, releasing the physical layer connection.
There are currently eleven types of LCP packets. These types are illustrated in Table 1 below, along with the direction in which they travel (from Initiator (I) to responder (R) or vice-versa) and their description.
In recent years, “intranets” have been rising in popularity, especially with large companies. An intranet is an internal network that serves only a specific type of person (such as employees of a corporation, or students at a school). The intranet is usually not accessible to the general public. Intranets have become popular mainly because they allow for much more productive communication between users within the network,
TABLE 1
Name
Direction
Description
Configure-request
I → R
List of proposed options and values
Configure-ack
I ← R
All options are accepted
Configure-nak
I ← R
Some options are not accepted
Configure-reject
I ← R
Some options are not negotiable
Terminate-request
I → R
Request to shut down the line
Terminate-ack
I ← R
OK to shut down the line
Code-reject
I ← R
Unknown request received
Protocol-reject
I ← R
Unknown protocol received
Echo-request
I → R
Please send this frame back
Echo-reply
I ← R
Here is the frame back
Discard-request
I → R
Discard this frame (for testing)
even when the users are dispersed over a wide geographic area (such as in multi-national corporations).
FIG. 1
is a block diagram depicting the typical connection to an intranet. Personal computer
10
connects through a link
12
to an Internet service provider (ISP) or access point (AP)
14
. The ISP or AP
14
then connects through link
16
to the Intranet
18
.
Many entities that maintain intranets, however, have also wanted to offer users access to the Internet or to other intranets as well. There were, however, a limited number of ways that this could be accomplished. The first, and most simple, way would be for the user to first terminate the existing PPP connection between the PC
10
and the ISP or access point
24
. Then the user could log into a second intranet or to the Internet. The major drawbacks of this solution are obvious. It does not allow for simultaneous connection to two intranets, or to one intranet and the Internet, thus limiting the productivity of the user. Additionally, it requires termination of the PPP link between the PC and the ISP, thus using up valuable time on the user's end, as he has to re-initiate a connection process.
The second way an entity could offer access to a second intranet or to the Internet is to have a preconfigured connection from the intranet to the second intranet or Internet, such that communications between the user and the second intranet or Internet pass through the intranet.
FIG. 2
is a block diagram illustrating a connection to the Internet
62
through an intranet
58
. A user at PC
50
maintains a PPP connection
52
to ISP
54
, which is connected to the intranet
58
. Intranet
58
is then connected through link
60
to the Internet
62
. The drawback of this solution is that the traffic from the user at PC
50
to the Internet
62
passes through the intranet
58
. This increases the traffic traveling through the intranet
58
and poses a security risk to the information sent via the intranet
58
.
One major drawback of PPP, therefore, is that it is designed as a point to point protocol, meaning that it is designed for use between two endpoints. Therefore, it is currently not possible for a user to connect to two independent endpoints simultaneously (such as an intranet and the Internet, or to two independent intranets) using a single PPP link.
What is needed is a method by which a user may connect to two independent endpoints simultaneously using a single PPP link.
SUMMARY OF THE INVENTION
Multiple simultaneous network connections from a single PPP connection may be accomplished by utilizing a gateway in the following manner. A first network connection is established between the gateway and a first network. A first real network address for the user is then received, the first real network address assigned by the first network. Then, the gateway may establish a network session between the gateway and a second network and receive a second real network address for the user, the second real network address assigned by the second network. A virtual network address may be assigned to the user for network address translation purposes. Additional network connections may be added in a similar manner. Network address translation is then performed on packets traveling between the user and any of the network sessions. This allows each of the simultaneous network connections to gain the benefits of network address translation.
REFERENCES:
patent: 4922486 (1990-05-01), Lidinsky et al.
patent: 5136580 (1992-08-01), Videlock et al.
patent: 5274631 (1993-12-01), Bhardwaj
patent: 5280480 (1994-01-01), Pitt et al.
patent: 5423002 (1995-06-01), Hart
patent: 5430715 (1995-07-01), Corbalis et al.
patent: 5555244 (1996-09-01), Gupta et al.
patent: 5570361 (1996-10-01), Norizuki et al.
patent: 5583862 (1996-12-01), Callon
patent: 5592470 (1997-01-01), Rudrapatna et al.
patent: 5594732 (1997-01-01), Bell et al.
patent: 5617417 (1997-04-01), Sathe et al.
patent: 5659542 (1997-08-01), Bell et al.
patent: 5671354 (1997-09-01), Ito et al.
patent: 5673265 (1997-09-01), Gupta et al.
patent: 5699521 (1997-12-01), Iizuka et al.
patent: 5737526 (1998-04-01), Periasamy et al.
patent: 5740171 (1998-04-01), Mazzola et al.
patent: 5740176 (1998-04-01), Gupta et al.
patent: 5787253 (1998-07-01), McCreery et al.
paten
Chu Jie
Dos Santos Maria Alice
Jin Jane Jiaying
Lou Shuxian
Zhang Shujin
Cisco Technology Inc.
Hanish Marc S.
Jung Min
Thelen Reid & Priest LLP
LandOfFree
Multiple network connections from a single PPP link with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multiple network connections from a single PPP link with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multiple network connections from a single PPP link with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2970805