FIELD OF INVENTION

This invention relates to computer networks. More specifically, it relates to a protocol and method for peer network device discovery in computer networks.

BACKGROUND OF THE INVENTION

The Internet is a world-wide network of interconnected computers. One component of the Internet includes a large number of individual networks called Autonomous Systems (“AS”). Autonomous Systems include network topologies that typically have a single administrative entity. Examples of Autonomous Systems include universities (e.g., mit.edu, wisconsin.edu, etc.), corporations (3com.com, microsoft.com, etc.) and Internet Service Providers (“ISP”) (e.g., aol.com, mci.com, etc.). An individual Autonomous System may include one or more Local Area Networks (“LAN”) connected by bridges or routers. As is known in the art, bridges store and forward data frames between network topologies, while routers translate differences between network protocols and route data packets to appropriate devices on a network topology. An Autonomous System may also include Wide Area Networks (“WAN”) running point-to-point or switched protocols.

Most Autonomous Systems comprise LANs connected by bridges or routers and only carry traffic to or from their own domain. Such Autonomous Systems are referred to as “stub” or “edge” networks and are typically interconnected to the Internet by a number of independent high speed backbone networks. Connectivity to the Internet in Autonomous Systems is often ad-hoc and based on administrative preferences rather than performance criteria. For example, network traffic between a first Autonomous System and a second Autonomous System in the same city may pass through another city tens or hundreds of miles away since the first and second Autonomous Systems may connect to the Internet through different backbones.

In some cases, multiple edge networks may be part of the same administrative entity. Large organizations with multiple sites use Virtual Private Networks (“VPN”) comprising multiple edge networks. Instead of using dedicated long-haul lines between sites, a VPN with Autonomous Systems connects each site through the Internet with an “edge router” or “firewall” typically capable of data encryption and/or data authentication. Data packets, such as Internet Protocol (“IP”) packets are encrypted and routed to the Internet traveling between multiple sites in the VPN. As is known in the art, IP is an addressing protocol designed to route traffic within a network or between networks.

Within an Autonomous System, routing and connectivity are typically determined by the organization's network administrator. Routing can be either static (e.g., statically assigned into a network device) or dynamic (e.g., using routing protocols such as Routing Internet Protocol (“RIP”), Open Shortest Path First (“OSPF”), etc.). For small to medium size Autonomous Systems, internal routes to the Internet do not change very often. Incoming and outgoing Internet traffic typically passes through a single router called a “gateway” or “edge router.” As is known in the art, a gateway stores and forwards data packets between dissimilar network topologies. However, on the Internet, routing is typically very dynamic. Paths between Autonomous Systems through the Internet may change minute-by-minute or they may remain static for long periods of time (e.g., days or weeks). Paths between Autonomous Systems may traverse several different backbones to complete an Internet connection. Routing on the Internet is discussed in “End-to-end routing behavior on the Internet,” by V. Paxson in

IEEE/ACM Transactions on Networking,

Vol. 5, No. 5, pp. 601-615, Octerber 1997, incorporated herein by reference.

There arc several problems associated with two or more Autonomous Systems with edge routers or firewalls using static routine to connect to the Internet, which uses dynamic routing. The Internet typically suffers from significant performance problems including excessive data packet delays and data packet losses that may addressly affect the Autonomous Systems. The data packet delays and losses typically occur at public Network Access Points (“NAP”) and private switches. Within each Autonomous System, network administration planning and fault tolerance can accommodate reasonable traffic growth for Internet connections. However, at Network Access Points, it is difficult to upgrade and maintain edge routers because multiple administrative entities for multiple Autonomous Systems arc involved.

There have been attempts to provide “intelligent” capabilities to edge routers. Intelligent edge router capabilities may include: Forward Error Correction (“FEC”), where loss resiliency is achieved by employing Forward Error Correcting Schemes, such as eXclusive-OR (“XOR”), Reed-Solomon codes, or other forward error correcting schemes known in the art; encryption, where performance and end-to-end privacy is enhanced with edge routers that encrypt packets that are being sent to edge networks with similar capabilities; compression, where performance is increased and bandwidth is reduced if packets are compressed and sent edge-to-edge; or other intelligence.

The “intelligent” edge router services described above and other services known in the art typically require that edge routers be able to identify each other (e.g., to negotiate an encryption or compression scheme). However, there is currently no mechanism to allow edge routers to identify one other using networking protocols (e.g., Transmission Control Protocol “TCP” ). As is known in the art, TCP provides a connection-oriented, end-to-end reliable protocol designed to fit into a layered hierarchy of protocols that support multi-network applications. Thus, it is desirable to provide a mechanism to allow “intelligent” edge routers to identify one another using networking protocols and increase network performance.

SUMMARY OF THE INVENTION

In accordance with a preferred embodiment of the present invention, problems associated with allowing “intelligent” edge routers to identify one another are overcome. A peer discovery protocol and peer discovery methods for peer network device discovery is presented. The peer discovery protocol includes a peer discovery marker for allowing a network device to discover a peer network device and a peer discovery table for storing peer network device information from a peer discovery marker. In a preferred embodiment of the present invention, the peer discovery marker is used as an additional option with an existing networking protocol such as TCP to allow discovery of peer network devices. However, the present invention is not limited to using the peer discovery marker with TCP, and other networking protocols could also be used.

The peer discovery table is maintained by a peer network device and is used with information from the peer discovery marker to record the existence of peer network devices. The peer table provides peer network device information in terms of two-way peer-to-peer data “flows” between subnets (e.g., peer network devices and associated host network devices) rather than connections between host network devices as is typically the case with router tables.

One aspect of a peer discovery method for a preferred embodiment of the present invention includes receiving an original first data packet from a first network device (e.g., a host network device) on a second network device (e.g., an edge router) on a first network. The first data packet (e.g., TCP/IP) is used to establish a connection from the first network device on the first network to a fourth network device on a second network (e.g., a host network device to another host network device). A peer discovery marker from a peer discovery protocol is added to a header in the first data packet on the second network device to create a modified first data packet as the packet passes through the second network device. The peer discovery marker includes a network address for the second network device that is trying to discover a peer network device. In a preferred embodiment of the present invention, the peer discovery marker is added as an additional networking option to a networking protocol such as TCP. The modified first data packet is sent from the second network device on the first network to a third network device on the second network via the third network (e.g., the Internet).

Another aspect of the peer discovery method for a preferred embodiment for the present invention includes receiving a modified first data packet on the third network device on the second network via the third network. Information from a peer discovery marker is extracted and stored in a first peer discovery table on the third network device. The peer discovery marker is deleted from the header on the modified first data packet on the third network device to recover the original first data packet. The original first data packet is sent to a fourth network device on the second network to help establish a connection between the first network device and the fourth network device.

Another aspect of the peer discovery method for a preferred embodiment for the present invention includes creating a second data packet on the third network device to establish a two-way peer-to-peer data flow to the peer second network device. The second data packet is created after the third network device receives a modified first data packet with a peer discovery marker. The second data packet can be a TCP, User Datagram Protocol (“UDP”) or other networking protocol data packet. As is known in the art, UDP provides a connectionless mode of communications with datagrams in an interconnected set of networks. The third network device adds its own network address and the network address of its associated host network device to the second data packet (e.g., IP addresses). The third network device sends the second data packet to the peer second network device via the third network (e.g., the Internet).

Information from the second data packet is extracted and stored in a second peer discovery table on the second network device, thereby providing network addresses for establishing a two-way, peer-to-peer data flow between the peer second network device and the peer third network device (e.g., peer edge routers) via the third network (e.g., the Internet).

In a preferred embodiment of the present invention, the first network device is a host computer, the second network device is an edge router, the third network device is an edge router, the fourth network device is a host computer. The first network and second networks are Autonomous Systems and the third network is the Internet. The first and second data packets are TCP/IP data packets, and the header including the peer discovery marker is a TCP header. However, the present invention is not limited to these network components and other network components could also be used.

The peer discovery protocol and peer discovery methods allow peer edge routers and other peer network devices to discover one another across a network like the Internet and provide “intelligent” edge router services. The peer discovery protocol and peer discovery method of a preferred embodiment of the present invention may enhance performance, reliability and security of data transmitted over the Internet to and from Autonomous Systems or other networks.

The foregoing and other features and advantages of a preferred embodiment of the present invention will be more readily apparent from the following detailed description, which proceeds with references to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a block diagram illustrating a network system for peer network address discovery;

FIG. 2

is a block diagram illustrating a protocol stack for a network device;

FIGS. 3A and 3B

are block diagrams illustrating components of a peer discovery protocol;

FIGS. 4A

,

4

B and

4

C are block diagrams illustrating TCP/IP three-way handshake segments for establishing a TCP connection;

FIG. 5

is a flow diagram illustrating a method for peer network device discovery;

FIG. 6

is a block diagram illustrating a peer discovery data packet with a peer discovery marker;

FIG. 7

is a flow diagram illustrating a method for peer network device discovery;

FIGS. 8A and 8B

are block diagrams illustrating peer discovery tables;

FIG. 9

is a flow diagram illustrating a method for peer network device discovery; and

FIG. 10

is a flow diagram illustrating a method for peer network device discovery.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Network System

FIG. 1

is a block diagram illustrating a network system

10

for preferred embodiment of the present invention. Network system

10

includes a first network

12

with multiple network devices, two of which arc illustrated. First network

12

includes a first network device

14

and a second network device

16

. Second network

18

also includes multiple network devices, two of which are illustrated. Second network

18

includes a third network device

20

and a fourth network device

22

. Second network device

16

and third network device

20

are connected via a third network

24

(e.g., the Internet).

In a preferred embodiment of the present invention, first network device

14

is a host network device (e.g., a computer), second network device

16

and third network device

20

are peer network devices (e.g., edge routers) and fourth network device

22

is a host network device. First network

12

and second network

18

are Autonomous Systems and third network

24

is the Internet. However, other network devices, network types and network components can also be used and the present invention is not limited to the network devices, network types and network components described for a preferred embodiment. In addition, although illustrated with four network devices, network system

10

typically includes tens to thousands of network devices in networks (

12

,

18

).

An operating environment for network devices of a preferred embodiment the present invention include a processing system with at least one high speed Central Processing Unit (“CPU”) and a memory system. In accordance with the practices of persons skilled in the art of computer programming, the present invention is described below with reference to acts and symbolic representations of operations that are performed by the processing system, unless indicated otherwise. Such acts and operations are referred to as being “computer-executed” or “CPU executed.” Although described with one CPU, alternatively multiple CPUs may be used for a preferred embodiment of the present invention.

The memory system may include main memory and secondary storage. The main memory is high-speed random access memory (“RAM”). Main memory can include any additional or alternative high-speed memory device or memory circuitry. Secondary storage takes the form of long term storage, such as Read Only Memory (“ROM”), optical or magnetic disks, organic memory or any other volatile or non-volatile mass storage system. Those skilled in the art will recognize that the memory system can comprise a variety and/or combination of alternative components.

It will be appreciated that the acts and symbolically represented operations include the manipulation of electrical signals by the CPU. The electrical signals cause transformation of data bits. The maintenance of data bits at memory locations in a memory system thereby reconfigures or otherwise alters the CPU's operation. The memory locations where data bits are maintained are physical locations that have particular electrical, magnetic, optical, or organic properties corresponding to the data bits.

The data bits may also be maintained on a computer readable medium including magnetic disks, optical disks, organic disks and any other volatile or non-volatile mass storage system readable by the CPU. The computer readable medium includes cooperating or interconnected computer readable medium, which exist exclusively on the processing system or may be distributed among multiple interconnected processing systems that may be local or remote to the processing system.

Network Device Protocol Stack

FIG. 2

is a block diagram illustrating a layered protocol stack

26

for a network device (e.g.,

14

,

16

,

20

, and

22

) in network system

10

. Layered Protocol stack

26

is described with respect to Internet Protocol suites comprising from lowest-to-highest, a link, network, transport and application layer. However, more or fewer layers could also be used, and different layer designations could also be used for the layers in protocol stack

26

(e.g., layering based on the Open Systems Interconnection (“OSI”) model).

Network devices (

14

,

16

,

20

, and

22

) are connected to networks (

12

,

18

, and

24

) with a link layer

28

. Link layer

28

includes Network Interface Card (“NIC”) drivers for hardware network devices connecting the network devices to a network (e.g., an Ethernet NIC). Above link layer

28

is a network layer

30

. Network layer

30

, includes an Internet Protocol (“IP”) layer

32

. As is known in the art, IP

32

is an addressing protocol designed to route traffic within a network or between networks. IP layer

32

, hereinafter IP

32

, is described in Internet Engineering Task Force (“IETF”) Request For Comments (“RFC”) RFC-791, incorporated herein by reference. In addition to IP

32

, other protocol layers may be used in network layer

30

including an Internet Control Message Protocol (“ICMP”) layer

34

.

ICMP layer

34

, hereinafter ICMP

34

, is used for network management. The main functions of ICMP

34

include error reporting, reachability testing (e.g., “pinging”) congestion control, route-change notification, performance, subnet addressing and other maintenance. For more information on ICMP

34

see RFC-792, incorporated herein by reference.

Above network layer

30

is a transport layer

36

. Transport layer

36

includes a Transmission Control Protocol (“TCP”) layer

38

and a User Datagram Protocol (“UDP”) layer

40

. TCP layer

38

, hereinafter TCP

38

, provides a connection-oriented, end-to-end reliable protocol designed to fit into a layered hierarchy of protocols which support multi-network applications. TCP

38

provides for reliable inter-process communication between pairs of processes in network devices attached to distinct but interconnected networks. For more information on TCP

38

see RFC-793, incorporated herein by reference.

UDP layer

40

, hereinafter UDP

40

, provides a connectionless mode of communications with datagrams in an interconnected set of computer networks. UDP

40

provides a transaction-oriented datagram protocol, where delivery and duplicate packet protection are not guaranteed. For more information on UDP

40

see RFC-768, incorporated herein by reference. Both TCP

38

and UDP

40

are not both required in protocol stack

26

.

Above transport layer is an application layer

42

where application programs reside to carry out desired functionality for a network device reside (e.g., application programs to provide “intelligent” services). More or fewer protocol layers can also be used in protocol stack

26

.

Peer Discovery Protocol

FIGS. 3A and 3B

are block diagrams illustrating components of a peer discovery protocol

44

. However, more or fewer peer discovery protocol components could also be used. As is illustrated in

FIG. 3A

, peer discovery protocol

44

includes a peer discovery marker

46

. Peer discovery marker includes a kind-field

48

, a length-field

50

and a network address-field

52

. However, more or fewer fields could also be used in peer discovery marker

46

. In a preferred embodiment of the present invention, peer discovery marker

46

includes a 1-byte kind-field

48

containing a unique number (e.g., 128). Length-field

50

is a 1-byte field indicating a length of the marker in bytes (e.g., 6 bytes). Network address-field

52

is a 4-byte field containing a network address (e.g., IP address) of a network device that wishes to be discovered. However, other field sizes and values could also be used and the present invention is not limited to the field sizes and values described.

As is illustrated in

FIG. 3B

, peer discovery protocol

44

also includes a peer discovery table

54

. Peer discovery table

54

includes a first column

56

, or “peer-field”, to store network addresses for peer network devices. Peer discovery table

54

also includes a second column

58

, or “peer host-field”, to store network addresses for host network devices associated with the peer network devices. An exemplary peer discovery table entry is illustrated by row

60

. However, more or fewer columns could also be used in peer discovery table

54

.

Network Device TCP Connection Establishment

For two network devices to establish a connection with TCP

38

, a TCP

38

three-way handshake is used.

FIGS. 4A

,

4

B and

4

C are block diagrams illustrating TCP/IP three-way handshake segments

62

. As an example, first network device

14

desires to establish a TCP

38

connection with fourth network device

22

. First network device

14

transmits a TCP

38

segment with a SYnchronize sequence Numbers (“SYN”) flag set, called a “TCP

38

SYN segment” to fourth network device

22

using IP

32

.

FIG. 4A

illustrates an exemplary TCP/IP SYN segment

64

sent from first network device

14

to fourth network device

22

. TCP/IP SYN segment

64

typically contains a TCP

38

Option for advertising a Maximum Segment Size (“MSS”) that the network device can accept. TCP

38

allows multiple configuration Options to be set. For more information on TCP

38

Options see RFC-793. TCP/IP SYN segment

64

illustrates an exemplary IP

32

address for first network device

14

of

128

.

10

.

20

.

31

as source IP

32

address and an IP

32

address for fourth network device

22

of

110

.

11

.

12

.

15

as destination IP

32

address. TCP/IP SYN segment

64

includes other fields that are normally set in the segments illustrated in FIG.

4

. However, such fields (e.g., TCP

38

header length, TCP

38

checksum, IP

32

total length) are not illustrated in FIG.

4

. For more information on such fields see RFC-793.

FIG. 4B

illustrates an exemplary TCP/IP SYN ACKnowledgment segment

66

. Fourth network device

22

responds to TCP/IP SYN segment

64

with “TCP/IP SYN ACK segment”

66

with the TCP

38

SYN, ACKnowledgment (“ACK”) and MSS option flags set and the IP

32

source and destination addresses reversed.

FIG. 4C

illustrates an exemplary TCP/IP ACK segment

68

. First network device

14

responds to TCP/IP SYN ACK segment

66

with a “TCP/IP ACK segment”

68

with ACK flags set. No TCP

38

option flags are set in the TCP/IP ACK segment.

The TCP/IP segments illustrated in

FIGS. 4A

,

4

B and

4

C do not contain any data. The segments are sent in a data packet as TCP

38

and IP

32

headers only with no data segment. After sending the TCP/IP ACK segment

68

, a TCP

38

connection is established between first network device

14

and fourth network device

22

. TCP

38

data can then be exchanged using IP

32

via third computer network

24

(e.g., the Internet).

Peer Network Device Discovery

As was illustrated above, first network device

14

on first network

12

typically initiates a TCP

38

connection to fourth network device

22

on second network

18

via third network

24

. It is desirable to allow second network device

16

functioning as an “edge router” to discover a network address of its peer edge router (e.g., third network device

20

) as the TCP

38

connection between host network devices first network device

14

and fourth network device

22

is being established. Once the edge routers have discovered each other, they can establish a two-way peer-to-peer “data flow” (i.e., another TCP

38

channel or a UDP

40

channel) between themselves and transmit information such as “intelligent” routing capabilities, requests, or commands and other information. Peer discovery is accomplished using peer discover protocol

44

.

FIG. 5

is a flow diagram illustrating a method

70

for peer network device discovery. At step

72

, an original first data packet is received from first network device

14

on second network device

16

on first network

12

. In a preferred embodiment of the present invention, the first data packet is a TCP/IP packet (e.g., TCP/IP SYN segment

64

,

FIG. 4A

) used to establish a TCP

38

connection from first network device

14

on first network

12

to fourth network device

22

on second network

18

. However, other data packets from other networking protocols could also be used.

At step

74

, peer discovery marker

46

from peer discovery protocol

44

is added to a header in the original first data packet on second network device

16

to create a modified first data packet. Peer discovery marker

46

includes a network address for second network device

16

(e.g., IP

32

address

128

.

10

.

20

.

30

).

FIG. 6

is a block diagram illustrating an exemplary peer discovery data packet

78

with a peer discovery marker

80

as a TCP

38

Option. Peer discovery data packet

78

is an exemplary modified first data packet created at step

74

. In a preferred embodiment of the present invention, peer discovery marker appears as an additional TCP Option in the TCP

38

header. However, peer discovery marker

46

may also be placed in another part of the TCP

38

header or in another networking protocol header. In addition, the present invention is not limited to using the peer discovery marker

46

as a TCP

38

Option and other types of peer discovery data packets could also be used.

Returning to

FIG. 5

at step

76

, the modified first discovery data packet is sent from second network device

14

on first network

12

, to third network device

20

on second network

18

, via third network

24

.

In a preferred embodiment of the present invention, first network device

14

(

FIG. 1

) transmits a TCP/IP SYN segment

64

(

FIG. 4A

) intended for fourth network device

22

(

FIG. 1

) to establish a TCP

38

connection. As TCP/IP SYN segment

64

passes through second network device

16

(i.e., a first edge router), second network device

16

puts its own IP

32

address (e.g.,

128

.

10

.

20

.

30

) in network address-field

52

(

FIG. 3A

) of peer discovery marker

46

. Kind-field

48

is set to

128

and length-field

50

is set to six, since the peer discovery marker is 6-bytes long.

Peer discovery marker

46

is added to TCP

38

header as an additional TCP

38

Option identified by a option “kind” number of

128

. The TCP

38

header is padded with TCP

38

No OPeration (“NOP”) bytes until it ends on a four-byte boundary (i.e., 8-bytes). Since the TCP/IP SYN segments do not carry a data payload, adding a 6-byte peer discovery marker and two-bytes of padding for a total of 8-bytes, will not adversely increase the size of the SYN segment beyond any Message Transfer Unit (“MTU”) previously defined by a network device.

Second network device

16

adjusts three fields in the TCP/IP SYN segment: IP

32

total length; TCP

38

header length; and TCP

38

checksum (fields not illustrated in the segments from FIG.

4

). The IP

32

and TCP

38

header lengths are increased by a fixed amount corresponding to the length of peer discovery marker

46

. In a preferred embodiment of the present invention, the TCP

38

checksum is computed by adding (e.g., in 16-bits 1's complement) the length of peer discovery marker

46

and associated padding to the original TCP

38

checksum. The original IP

32

length and TCP

38

header length values are subtracted from the TCP

38

checksum and the new IP

32

length and TCP

38

header length values are added to the TCP

38

checksum creating a new TCP

38

checksum. However, other methods can also be used to adjust the TCP

38

and IP header fields.

FIG. 7

is a flow diagram illustrating a method

82

for peer network device discovery. At step

84

, a modified first data packet (e.g., a TCP/IP packet with a peer discovery marker

46

in a TCP

38

header) is received on third network device

20

(i.e., a second edge router) on second network

18

via the third network

24

. At step

86

, information from the peer discovery marker in

46

the modified first data packet is extracted and stored in a first peer discovery table on the third network device

20

(e.g., the network address of second network device

16

). At step

88

, peer discovery marker

46

is deleted from the header in the peer discovery data packet by third network device

20

to recover an original first data packet (e.g., TCP/IP SYN segment

64

). At step

90

, the original first data packet is sent to fourth network device

22

.

In a preferred embodiment of the present invention, third network device

20

(i.e., second edge router) removes peer discovery marker

46

from TCP

38

header. The network address for the peer network device (e.(g., second network device

16

) from peer discover marker

46

is stored in a peer discovery table along with the network address for the host network device associated with the peer network device from the IP

32

header (e.g., from the IP

32

source field).

FIGS. 8A and 8B

are block diagrams illustrating exemplary peer discovery tables.

FIG. 8A

is a block diagram illustrating an exemplary peer discovery table

92

for peer third network device

20

created as a result of execution of methods

70

(

FIG. 5

) and

82

(FIG.

7

). Peer discovery table

86

(

FIG. 8A

) includes a network address (i.e., an IP

32

address

128

.

10

.

20

.

30

) for a peer network device, which is second network device

16

, and a network address for its associated host network device, first network device

14

(i.e.,

128

.

10

.

20

.

31

).

Third network device

20

re-calculates the IP

32

length, TCP

38

header length, and TCP

38

checksum fields using an inverse of the calculation described for adding peer discovery marker

46

to the TCP

38

header. However, other calculations can also be used for removing peer discovery

46

. This inverse calculation recovers an original data packet (e.g., TCP/IP SYN segment

64

), which is sent to fourth network device

22

to help establish a TCP

38

connection.

FIG. 9

is a flow diagram illustrating a method

100

for peer network device discovery. At step

102

, a second data packet is created on third network device

20

after receiving a modified data packet with a peer discovery marker

46

. In a preferred embodiment of the present invention, the second data packet is a TCP

38

data packet. However, other data packets could also be used (e.g., UDP

40

or other networking protocol data packets).

At step

104

, third network device

20

adds its network address (e.g., IP

32

address

110

.

11

.

12

.

14

) and a network address (e.g., IP

32

address

110

.

11

.

12

.

15

) for an associated host network device to the second data packet.

At step

106

, the second data packet is sent from third network device

20

on second network

18

to peer second network device

16

on first network

12

via third network

24

. Third network device

20

uses the second data packet to initiate a two-way peer-to-peer data flow to peer second network device

16

. The two-way peer-to-peer data flow is established outside of, and separate from, the TCP

38

connection being established between first network device

14

and fourth network device

22

. For example, the second data packet is sent from third network device

20

to peer second network device

16

to establish a two-way peer-to-peer data flow connection as second network device

16

is sending the TCP

38

handshake segments illustrated in

FIG. 4

to third network device

20

to establish a TCP

38

connection between first network device

12

and fourth network device

22

.

FIG. 10

is a flow diagram illustrating a method

108

for peer network device discovery. At step

110

, a second data packet is received on second network device

16

on first network

12

via the third network

24

from third network device

20

. At step

112

, network address information for a peer network device and its associated peer host network device is extracted from the second data packet. At step

114

, the network address information extracted from second data packet is stored in a peer discovery table (e.g., peer discovery table

96

of

FIG. 8B

) on second network device

16

. Peer discovery table

96

(

FIG. 8B

) includes a network address (e.g., an IP

32

address) for a peer network device, which is third network device

20

, and a network address for its associated host, fourth network device

22

. Peer discovery table

96

includes an exemplary table entry

98

illustrating an network address (i.e., IP

32

address

10

.

11

.

12

.

14

) for peer third network device

20

and its associated host, fourth network device

22

(i.e., IP

32

address

110

.

11

.

12

.

15

).

In one embodiment of the present invention, peer third network device

20

and peer second network device

16

execute the TCP

38

handshake sequence illustrated in FIG.

4

and described above to establish a two-way peer-to-peer TCP

38

data flow (e.g., a TCP

38

channel) between peer network devices. However, other peer-to-peer data-flows may also be established between the peer network devices (e.g., a UDP

40

channel or other networking protocol channel).

A two-way, peer-to-peer data flow is established between the peer network devices (

16

,

20

) via third network

24

as first network device

12

and fourth network device

22

are establishing a TCP

38

connection. The peer-to-peer data flow is separate from the TCP

38

connection established between first network device

14

and fourth network device

22

.

Peer second network device

16

is able to determine that fourth network device

22

is reached via peer third network device

20

with peer discovery table

96

. Peer third network device

20

is able to determine that first network device

14

is reached via peer second network device

16

with peer discovery table

92

. The peer-to-peer network devices can now exchange routing “intelligent” routing capabilities, requests, or commands and other information. The exchange of information allows the peer network devices to exchange and negotiate “intelligent” edge router capabilities such as error correction, encryption, compression, and other data transmission parameters that may improve transmission bandwidth between Autonomous Systems.

In a preferred embodiment of the present invention, the modified first data packet is a TCP/IP data packet with a peer discovery marker

46

added to the TCP

48

header as an additional TCP

38

Option. In such an embodiment, if a network device receives a modified data packet with peer discovery marker

46

, and the network device does not implement peer discovery protocol

44

and the peer discovery methods described herein, peer discovery marker

46

is ignored. The default action for TICP

38

upon receipt of an unknown TCP

38

Option is to silently ignore the unknown TCP

38

Option. Thus, attempting to use the peer discovery protocol and methods with TCP

38

described herein, should not have any adverse effects on existing network devices that do not implement peer discovery (i.e., assuming that a network device has a proper implementation of TCP

38

that handles unknown TCP

38

options correctly).

The peer discovery protocol and peer discovery method described here allow peer edge routers and other peer network devices to discover one another across a network like the Internet using existing networking protocols. The peer network devices can then provide “intelligent” edge router services such as error correction, encryption, compression and other services. The peer discovery protocol of the present invention is used with existing networking protocols used for the Internet and can be used with network devices that do not implement the peer discovery protocol without disruption. Thus, the peer discovery protocol and peer discovery methods of a preferred embodiment of the present invention may enhance performance, reliability and security of data transmitted over the Internet to and from Autonomous Systems or other subnets or networks.

In view of the wide variety of embodiments to which the principles of the present invention can be applied, it should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the present invention. For example, the steps of the flow diagrams may be taken in sequences other than those described, and more or fewer elements may be used in the block diagrams.

The claims should not be read as limited to the described order or elements unless stated to that effect. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the invention.