Abstract: The present invention provides a wide-sense, non-blocking WDM cross-connect that utilizes a relatively small number of wavelength interchangers. The cross-connect of the present invention comprises first, second and third fabrics and one or more wavelength interchangers that interconnect the first and second fabrics. Demands that require a change in wavelength are routed through the first fabric, through one or more of the wavelength interchangers, and through the second fabric. Demands that do not require a change in wavelength are only routed through the third fabric. A routing algorithm is utilized to ensure that any sequence of connection requests and withdrawals can be routed without disturbing any currently routed requests.

Abstract: A method for exchanging routing information between I-BGP routers within an autonomous system (AS) advantageously enables a solution to both persistent route oscillation problems and transient route oscillation problems which may occur when using I-BGP in a given AS. Conventional I-BGP protocol techniques are extended by enabling I-BGP speakers (e.g., routers) to communicate a set of possible best paths to a given destination, rather than communicating only a single best path, to each of their I-BGP peers within the given AS. Specifically, a plurality of possible best paths to a destination are communicated (where there are in fact more than one) from an I-BGP speaker in a given AS to its I-BGP peers (within the given AS), for each neighboring AS that provides any such paths (i.e., routes to the destination).

Abstract: A method for exchanging routing information between I-BGP routers within an autonomous system (AS) advantageously enables a solution to both persistent route oscillation problems and transient route oscillation problems which may occur when using I-BGP in a given AS. Conventional I-BGP protocol techniques are extended by enabling I-BGP speakers (e.g., routers) to communicate a set of possible best paths to a given destination, rather than communicating only a single best path, to each of their I-BGP peers within the given AS. Specifically, a plurality of possible best paths to a destination are communicated (where there are in fact more than one) from an I-BGP speaker in a given AS to its I-BGP peers (within the given AS), for each neighboring AS that provides any such paths (i.e., routes to the destination).

Abstract: The present invention provides a strictly non-blocking WDM cross-connect that utilizes a relatively small number of wavelength interchangers. The cross-connect of the present invention comprises two fabrics and one or more wavelength interchangers that interconnect the fabrics. The fabrics are either pathwise strictly non-blocking or pathwise wide-sense non-blocking. In the former case, the WDM cross-connect is strictly non-blocking, i.e., both pathwise and wavelength strictly non-blocking. In the latter case, the cross-connect is wavelength strictly non-blocking and is pathwise wide-sense non-blocking, i.e., a routing algorithm is required to ensure that any sequence of connection requests and withdrawals can be routed without disturbing any currently routed requests.

Abstract: The present invention provides a strictly non-blocking WDM cross-connect that utilizes a relatively small number of wavelength interchangers. In accordance with one embodiment, the WDM cross-connect utilizes n1k1 wavelength interchangers, where n1 is an integer equal to the number of wavelengths carried on an input optical fiber associated with the WDM cross-connect and k1 is the total number of input optical fibers to the WDM cross-connect. Each of the wavelength interchangers is connected to exactly one input port of the fabric and each input port of the fabric is connected to exactly one wavelength interchanger. The input optical fibers of the WDM cross-connect are connected to k1 optical switches of the cross-connect that separate out the n1 wavelengths onto n1 optical fibers, which are input to respective wavelength interchangers. Therefore, each wavelength interchanger receives exactly n1 optical fibers.