Method for forwarding data packets as cell sequences within a subnetwork of a data packet network
First Claim
1. Method for forwarding a data packet within a subnetwork (S) which comprises a first plurality of interconnected cell switching nodes (1,2,3,4), surrounded by and coupled to a second plurality (A,B,C,D,E) of edge packet routers included in said subnetwork, said subnetwork further being surrounded and part of a data packet network of routers which are adapted to route said data packet from a source router to at least one destination router of said data packet network of routers, via said subnetwork from an ingress edge packet router (B), at least one cell switching node (1) of said second plurality, to at least one destination egress edge packet router (A,C,D,E) of said second plurality, said method including a step of associating, a destination forwarding tag to said data packet, a further step of deriving, from said data packet and said destination forwarding tag, a sequence of fixed length cells for further transmission to said at least one cell switching node (1) of said first plurality, and a further step of dynamically analyzing, within said at least one cell switching node (1) of said first plurality, said destination forwarding tag for elaborating a packet cell forwarding decision applicable to all cells of said sequence, and for thereby performing a subsequent transfer action of said all cells, to at least one outgoing link of said at least one cell switching node (1), according to said forwarding decision, whereby to each one of the edge packet routers (A,B,C,D,E) of said second plurality a distinct local edge router identity, specific of said subnetwork (S), is assigned, and whereby said destination forwarding tag includes at least one destination egress edge router local identifier which is related to said distinct local edge router identity assigned to said at least one destination egress edge packet router (A,C,D,E).
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Abstract
A method is described for forwarding a data packet within a subnetwork (S) of interconnected cell switching nodes (1,2,3,4), surrounded by edge packet routers (A,B,C,D,E), which are further surrounded and part of a data packet network of routers. Said data packet enters said subnetwork via an ingress edge packet router (B), passes through at least one cell switching node (1), and leaves it via at least one destination egress edge packet router (A,C,D,E). The method includes the steps of associating a destination forwarding tag to said data packet, of deriving a sequence of fixed length cells for further transmission to said at least one cell switching node (1), of dynamically analyzing said destination forwarding tag for elaborating a packet cell forwarding decision applicable to all cells of said sequence, and thereby performing a subsequent transfer action of said all cells, to at least one outgoing link. Essential is that each edge packet router is assigned a distinct local edge router identity, specific of said subnetwork, and that said destination forwarding tag includes at least one destination egress edge router local identifier which is related to said local edge router identity of the destination egress edge packet routers (A,C,D,E). Ingress edge packet routers and cell switching node adapted to perform this method are also described.
74 Citations
22 Claims
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1. Method for forwarding a data packet within a subnetwork (S) which comprises a first plurality of interconnected cell switching nodes (1,2,3,4), surrounded by and coupled to a second plurality (A,B,C,D,E) of edge packet routers included in said subnetwork, said subnetwork further being surrounded and part of a data packet network of routers which are adapted to route said data packet from a source router to at least one destination router of said data packet network of routers, via said subnetwork from an ingress edge packet router (B), at least one cell switching node (1) of said second plurality, to at least one destination egress edge packet router (A,C,D,E) of said second plurality, said method including
a step of associating, a destination forwarding tag to said data packet, a further step of deriving, from said data packet and said destination forwarding tag, a sequence of fixed length cells for further transmission to said at least one cell switching node (1) of said first plurality, and a further step of dynamically analyzing, within said at least one cell switching node (1) of said first plurality, said destination forwarding tag for elaborating a packet cell forwarding decision applicable to all cells of said sequence, and for thereby performing a subsequent transfer action of said all cells, to at least one outgoing link of said at least one cell switching node (1), according to said forwarding decision, whereby to each one of the edge packet routers (A,B,C,D,E) of said second plurality a distinct local edge router identity, specific of said subnetwork (S), is assigned, and whereby said destination forwarding tag includes at least one destination egress edge router local identifier which is related to said distinct local edge router identity assigned to said at least one destination egress edge packet router (A,C,D,E).
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10. Ingress edge packet router (B) of a subnetwork (S), which comprises a first plurality of interconnected cell switching nodes (1,2,3,4), surrounded by and coupled to a second plurality of edge packet routers (A,B,C,D,E) included in said subnetwork (S) and of which said ingress edge packet router (B) forms part, said subnetwork (S) further being surrounded and part of a data packet network of routers which are adapted to route a data packet from a source router to a destination router of said data packet network of routers, via said ingress edge packet router (B) to at least one destination egress edge packet router (D) of said second plurality, said ingress edge packet router being adapted to receive said data packet from said data packet network, and to associate to said data packet a destination forwarding tag relating to said at least one destination egress edge packet router (D) of said second plurality, to further derive, from said data packet and from said destination forwarding tag, a sequence of fixed length cells for further transmitting this packet cell sequence to at least one cell switching node (1) of said first plurality,
characterized in that said ingress edge packet router (B) is further adapted to assign, to each one of the edge packet routers of said second plurality, a distinct local edge router identity which is specific to said subnetwork (S), so that said destination forwarding tag, associated to said data packet, includes at least one destination egress edge router local identifier which is related to said distinct local edge router identity assigned to this said at least one destination egress edge packet router (D).
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18. Cell switching node (1;
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4) of a subnetwork (S) which comprises a first plurality of interconnected cell switching nodes (1,2,3,4) of which said cell switching node (1;
4) forms part, said plurality being surrounded by and coupled to a second plurality of edge packet routers (A,B,C,D,E) included in said subnetwork (S), said subnetwork (S) further being surrounded and part of a data packet network of routers which are adapted to route said data packet from a source router to a destination router of said data packet network of routers, via an ingress edge packet router (B) of said second plurality to at least one destination egress edge packet router (A,C,D;
E) of said second plurality, whereby said cell switching node (1;
4) is adapted to receive, either from an ingress edge packet router (B) or from another cell switching node (1) of said subnetwork (S), a packet cell sequence, to elaborate a forwarding decision applicable to all cells of said sequence for transferring all of said cells to at least one outgoing link of said cell switching node (1;
4) according to said forwarding decision, and to perform a packet cell forwarding operation based upon a destination forwarding tag present in one or more cells of said cell packet sequence, said destination forwarding tag including at least one destination egress edge router local identifier which is related to a distinct local edge router identity specifically assigned to said at least one destination egress edge packet router (A,C,D;
E) within said subnetwork (S). - View Dependent Claims (19, 20, 21, 22)
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4) of a subnetwork (S) which comprises a first plurality of interconnected cell switching nodes (1,2,3,4) of which said cell switching node (1;
Specification