Abstract: A system and method are disclosed for generating segment routing (SR) segment lists. In one embodiment, a node receives information that identifies a path from a first node to a second node. Based on the received path, a set of segment identifiers that encodes the path is generated. A packet that is forwarded along the set of segment identifiers travels the received path.

Abstract: In one embodiment, a packet and a segment ID stack is received at a node. The segment ID stack includes a plurality of segment IDs, one or which is a first area-segment ID that identifies a first area of a subdivided network. One of a plurality of forwarding tables at the node is selected based on the first area-segment ID. Thereafter, the packet is forwarded based on information contained in the selected forwarding table.

Abstract: A method and system are disclosed for use of segment routing in monitoring of a network path. In one embodiment, the method includes selecting a plurality of segment identifiers and assembling the segment identifiers into a segment identifier stack, where the segment identifier stack encodes a test path within the network for attempted routing of a test message. The method may further include inserting the segment identifier stack into a header associated with the test message, and forwarding the test message according to an entry in a forwarding table corresponding to the segment identifier at the top of the segment identifier stack. Interior gateway protocol advertisements may be used to communicate segment identifiers for creating or updating of the data structure or the forwarding table. In an embodiment, the system includes one or more network interfaces and a processor configured to perform the steps of the method.

Abstract: One or more functions to be performed on a packet at one or more network nodes along a network path are determined at a network device. A packet is generated which includes a packet header. Included in the packet header are an instruction pointer and an instruction portion. A first instruction for the one or more functions to be performed at the one or more network nodes is written to the instruction portion. Additionally, a value pointing to the first instruction is written to the instruction pointer. The packet is transmitted along the network path from the network device.

Abstract: An apparatus and method is disclosed for segment routing (SR). In one embodiment, the method includes a node creating a segment stack that identifies one segment calculated using a first algorithm and a second segment calculated using a second, different algorithm. The node then attaches this header to a packet and sends it to another node.

Abstract: MPLS segment routing is disclosed. In one embodiment, a first core router generates a first data structure that maps first portcodes to respective identities of first neighbor routers or respective first links, wherein the first portcodes identify respective first ports of the first core router, and wherein the first ports are coupled to the first neighbor routers, respectively, via the first links, respectively. The first core router generates and transmits a first link-state packet, wherein the first link-state packet comprises an identity of the first core router and the first data structure.

Abstract: An apparatus and method as described for constructing a repair path for use in the event of failure of an inter-routing domain connection between respective components in first and second routing domains of a data communications network. The apparatus is arranged to assign a propagatable repair address for use in the event of failure of the inter-routing domain connection and to propagate the repair address via data communications network components other than the inter-routing domain connection.

Abstract: An apparatus for providing reachability in a routing domain of a data communications network having as components nodes and links therebetween for a routing domain external destination address is provided. The apparatus is arranged to advertise destination address reachability internally to nodes in the routing domain and associate a reachability category with the internal advertisement of the destination address reachability.

Abstract: An apparatus is described for forwarding data in a data communications network having as components nodes and links therebetween in which nodes obtain a reachability metric between a neighbor node and one or more other nodes in the network and in which a repair path is created between an instigating repair node and a receiving repair node around a failure component therebetween. A propagatable repair address for the receiving repair node is reachable by the repair path notvia the failure component. The apparatus is arranged to treat propagatability of the repair address differently via the failure component than via other components.

Abstract: In one embodiment, an apparatus and method are described for constructing a repair path in the event of non-availability of a routing domain component of a routing domain comprising, as components, links and nodes. The apparatus is arranged to receive respective network repair addresses from each of the far-side and near-side advertising node for use in the event of non-availability of a routing domain component between the advertising node. The apparatus is further arranged to advertise the near-side advertising node network repair address to one or more far-side nodes via a path external to the routing domain.

Abstract: An apparatus and method as described for constructing a repair path for use in the event of failure of an inter-routing domain connection between respective components in first and second routing domains of a data communications network. The apparatus is arranged to assign a propagatable repair address for use in the event of failure of the inter-routing domain connection and to propagate the repair address via data communications network components other than the inter-routing domain connection.

Abstract: An apparatus is described for forwarding data in a data communications network having as components nodes and links therebetween in which nodes obtain a reachability metric between a neighbor node and one or more other nodes in the network and in which a repair path is created between an instigating repair node and a receiving repair node around a failure component therebetween. A propagatable repair address for the receiving repair node is reachable by the repair path notvia the failure component. The apparatus is arranged to treat propagatability of the repair address differently via the failure component than via other components.

Abstract: In one embodiment, an apparatus and method are described for constructing a repair path in the event of non-availability of a routing domain component of a routing domain comprising, as components, links and nodes. The apparatus is arranged to receive respective network repair addresses from each of the far-side and near-side advertising node for use in the event of non-availability of a routing domain component between the advertising node. The apparatus is further arranged to advertise the near-side advertising node network repair address to one or more far-side nodes via a path external to the routing domain.

Abstract: An apparatus for providing reachability in a routing domain of a data communications network having as components nodes and links therebetween for a routing domain—external destination address is described. The apparatus is arranged to advertise destination address reachability internally to nodes in the routing domain and associate a reachability category with said internal advertisement of said destination address reachability.

Abstract: A method for processing token identifiers for Layer 3 (L3) control channels when encapsulated in a tunneling protocol. Rather than encapsulating an L3 control channel with a secondary L3 (or Layer 4 ‘L4 ’) header, a generic (non-Layer 3 header) identifier, or token identifier, is used to encapsulate the control channel. For example, the token identifier may be a simple bit pattern that does not require a complex, confusing or redundant IP/UDP routing table lookup. Instead, the token identifier simply alerts the forwarding entity that local processing of the packet's data is required (e.g., that the packet contains control channel data).

Abstract: A packet forwarding node for a computer network comprises at least one receiving module and at least one output module including packet list (21) for maintaining a list of packets to be transmitted therefrom. The time for which a packet remains in the node is determined by grouping the packets into groups or "buckets" which are created at regular intervals, each bucket containing packets arriving within the same time interval, and keeping track of the age of each bucket. A bucket counter (33) counts the total number of buckets in existence, so indicating the age of the oldest packet. This counter is incremented by 1 at regular intervals and decremented by 1 each time the oldest bucket is emptied (or found to be empty). A bucket list shift register (30) has its contents shifted at each change of time interval, and its the bottom stage accumulates the number of packets arriving in a time interval, and an overflow accumulator (31) accumulates counts shifted out of its top end.

Abstract: The present invention provides an interlock scheme for use between a line card and an address recognition apparatus. The interlock scheme reduces the total number of read/write operations over a backplane bus coupling the line card to the address recognition apparatus required to complete a request/response transfer. Thus, the line card and address recognition apparatus are able to perform a large amount of request/response transfers with a high level of system efficiency. Generally, the interlocking scheme according to the present invention merges each ownership information storage location into the location of the request/response memory utilized to store the corresponding request/response pair to reduce data transfer traffic over the backplane bus. According to another feature of the interlock scheme of the present invention, each of the line card and the address recognition engine includes a table for storing information relating to a plurality of database specifiers.

Abstract: The present invention is directed to an address recognition apparatus including an address recognition engine coupled to a look-up database. The look-up database is arranged to store network information relating to network addresses. The look-up database includes a primary database and a secondary database. The address recognition engine accepts as an input a network address for which network information is required. The address recognition engine uses the network address as an index to the primary database. The primary database comprises a multiway tree node structure (TRIE) arranged for traversal of the nodes as a function of preselected segments of the network address and in a fixed sequence of the segments to locate a pointer to an entry in the secondary database. The entry in the secondary database pointed to by the primary database pointer contains the network information corresponding to the network address. The address recognition engine includes a table for storing a plurality of database specifiers.

Abstract: A high performance data link interface includes receive and transmit data framing paths. The data link interface interlocks certain communication link control signals, such as the CCITT standard data set signals, with data being received or transmitted through the interface to correlate a transmission error directly to a particular data transmission for rapid and efficient error recovery.

Abstract: A method and apparatus for aliasing an address for a location in a memory system. The aliasing permits an address generating unit to access a memory block of variable size based upon an address space of fixed size so that the size of the memory block can be changed without changing the address generating software of the address generating unit. The invention provides an address aliasing device arranged to receive an address from the address generating unit. The address aliasing device includes a register that stores memory block size information. The memory block size information is read by the address aliasing device and decoded to provide bit information representative of the size of the memory block. The address aliasing device logically combines the bit information with appropriate corresponding bits of the input address to provide an alias address that is consistent with the size of the memory block.