TECHNIQUE FOR DUAL HOMING INTERCONNECTION BETWEEN COMMUNICATION NETWORKS

• US 20120147740A1
• Filed: 08/09/2010
• Published: 06/14/2012
• Est. Priority Date: 08/20/2009
• Status: Active Grant

• Current Assignee: ECI Telecom Limited (Shaul Shani)
• Original Assignee: ECI Telecom
• Inventors: Nakash, Shell
• Granted Patent: US 9,509,591 B2
• Time in Patent Office: Days
• US Class Current: 370/221
• CPC Class Codes: H04L 12/437 Ring fault isolation or reconfiguration for SDH/SONET ring networks H04J3/085
• CPC Class Codes: H04L 12/4604 LAN interconnection over a backbone network, e.g. Internet, Frame Relay
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/18 Loop-free operations
• CPC Class Codes: H04L 45/22 Alternate routing

Abstract

A dynamically self-configuring and re-configuring dual homing connection (DH) for loop-free data communication between a first communication network and a second communication network, the DH acquiring either a Symmetrical configuration or an Asymmetrical configuration.

Claims

1-14. -14. (canceled)

15. A method for establishing loop free data communication between a first communication network and a second communication network via a dual homing connection DH, wherein the dual homing connection is formed by four nodes and a ring-like connection there-between provided by four communication lines, two of said lines being inter-network lines respectively connecting two inter-network pairs out of said nodes, wherein each said inter-network pair comprises nodes residing in different said two networks, and the remaining two of said lines being intra-network lines respectively connecting two intra-network pairs of said nodes called intra-network node pairs, wherein a first intra-network node pair resides in the first communication network and a second intra-network node pair resides in the second communication network, the method comprising:

ensuring that all the four communication lines are capable of carrying data traffic to be communicated via the DH;

locally running on each of the two intra-network node pairs an instance of a loop protocol via its associated intra-network line, independently from the protocol instance run on the other intra-network node pair of the DH;

independently and dynamically selecting, by each of the protocol instances, a Primary node and a Secondary node in a specific intra-network node pair running the protocol instance;

enabling each of the intra-network node pairs to utilize suitable inter-network and intra-network paths for carrying data traffic to be communicated via the DH; and

establishing data traffic communication between the first and the second networks;

either by using a first, symmetric configuration of the DH, by establishing direct data traffic communication between the Primary node of the first intra-network node and the Primary node of the second intra-network node pair via an inter-network line out of said four communication lines;

or

by using a second, asymmetric configuration of the DH, by establishing indirect data traffic communication between the Primary node of the first intra-network node and the Primary node of the second intra-network node pair, via inter-network and intra-network lines out of said four communication lines.

16. The method according to claim 15, wherein said protocol provides the following Working rules W1 to W4 for establishing an initial configuration of the DH:

(W1) Only a Primary node sends traffic over an inter-network communication line, while a Secondary GW does not send traffic over an inter-network communication line;

(W2) a Primary node receiving traffic over either inter-network or intra-network communication line forwards it to the local network where it resides; and

(W3) a Secondary node receiving traffic over an inter-network communication line forwards it over the intra-network communication line.

17. The method according to claim 15, wherein the protocol provides the following Switchover rules S1 to S3 for reconfiguring the DH upon a failure:

(S1) When a Primary node fails, the Secondary node of the same intra-network node pair takes over and becomes a new Primary node, wherein the failed Primary node is seen by the protocol run on the other intra-network node pair as if the associated inter-network communication line failed;

(S2) When an inter-network communication line fails, a Primary node not receiving traffic over it starts sending the traffic over the intra-network communication line instead;

(S3) When an intra-network communication line fails, a node not receiving traffic over said line starts sending remote failure indication RFI over said line and becomes Primary;

the node receiving RFI becomes Secondary and stops sending traffic over the associated inter-network communication line, thereby said inter-network line is seen as failed by the protocol run on the other intra-network node pair; and

(S4) When an inter-network line fails, a Secondary GW receiving traffic over an intra-network communication line forwards it to the other inter-network communication line.

18. The method according to claim 15, wherein the protocol provides the following Forwarding rules F1, F2 of the Primary node and F3, F4 of the Secondary node for handling unicast data packets to be forwarded from a local network being the first network to a remote network being the second network, or in the opposite direction:

F1) the Primary node, in case of receiving from an intra-network line a data packet originating from the remote network, learns its source address SA and handles it as if the packet were received from an inter-network line;

F2) the Primary node, in case of receiving a data packet from the local network, forwards the packet to the remote network over an inter-network line if it is Up, otherwise over an intra-network line;

F3) the Secondary node, in case of receiving a data packet from an inter-network line, learns its source address SA and forwards it to the intra-network line to the Primary node; and

F4) the Secondary node in case of receiving from an intra-network line a data packet addressed to the remote network, forwards it to the remote network over the inter-network line.

24. A software product comprising computer implementable instructions and data stored on a suitable non-transitory computer readable medium, wherein the software product, when being run in a processor of a node of a dual homing connection DH, is capable of enabling operations of the method according to claim 15.

19. A dual homing connection DH for loop-free data communication between a first communication network and a second communication network, wherein the dual homing connection comprises four nodes and a ring-like connection formed there-between by four communication lines, two of said lines being inter-network lines respectively connecting two inter-network pairs out of said nodes where each inter-network pair comprises nodes residing in different said two networks, and the remaining two of said lines being intra-network lines respectively connecting two intra-network pairs of said nodes, called intra-network node pairs, where a first intra-network node pair resides in the first communication network and a second intra-network node pair resides in the second communication network, in the DH:

all the four communication lines are capable of carrying data traffic to be communicated via the DH;

each of the two intra-network node pairs locally running an instance of a loop protocol via its associated intra-network line, independently from the protocol instance run by the other intra-network node pair of the DH;

each of the protocol instances is operative to independently and dynamically select a Primary node and a Secondary node in a specific intra-network node pair running the protocol instance;

each of the protocol instances enables utilizing inter-network and intra-network paths for carrying data traffic to be communicated via the DH; and

depending on selection of the Primary and the Secondary nodes in the two intra-network node pairs, said DH acquiring;

either a first, symmetric configuration where direct data traffic communication is established between the Primary node of the first intra-network node and the Primary node of the second intra-network node pair, via an inter-network line out of said four communication lines;

or

a second, asymmetric configuration where indirect data traffic communication is established between the Primary node of the first intra-network node pair and the Primary node of the second intra-network node pair, via inter-network and intra-network lines out of said four communication lines.

20. The DH connection according to claim 19, wherein an additional similar DH connection is formed between the first network and an additional, i-th network, by utilizing the first intra-network node pair and an additional intra-network node pair in the i-th network,

and wherein one and the same said protocol instance running on the first intra-network node pair serves both the DH connection between the first network and the second network, and the additional DH connection between the first network and the additional i-th network.

21. The DH connection according to claim 19, self-reconfigurable in case of a failure of any Primary node of the DH, or of an inter-network so, that the remaining nodes and communication lines of the dual homing connection DH are rearranged to restore communication between the first and the second networks by excluding said failed node or said failed inter-network communication line, and so that at least one of the intra-network communication lines is utilized to carry said data traffic before or after said failure.

22. The DH connection according to claim 19, operative to perform MAC flushing and MAC address relearning only in case of failure of any of the Primary nodes of the DH, and only at the network where the failed Primary node resides.

23. A combined network comprising a group of more than two communication networks, wherein one of said networks called a basic network is interconnected with the remaining two or more communication networks via two or more respective DH connections according to claim 19, and wherein each of said DH connections utilizes one and the same intra-network node pair located in said basic network and locally running said protocol instance.