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A multicast packet is transferred through a switching fabric from an input line card to a dedicated multicast card, which is substantially the same as an input and output line card, but without external facility interfaces. A dedicated output multicast card converts the multicast packet from an opti

A multicast packet is transferred through a switching fabric from an input line card to a dedicated multicast card, which is substantially the same as an input and output line card, but without external facility interfaces. A dedicated output multicast card converts the multicast packet from an optical to an electrical packet and passes it to a dedicated input multicast card, where the packet is replicated electrically, converted back to an optical packet, and then transferred through the switching fabric to multiple destinations. In some embodiments, input and output dedicated multicast cards are actually a single card. Transfer of the multicast packet to multiple destinations occurs sequentially or simultaneously during a single switching cycle, if multiple parallel switching paths exist through the switching fabric. Some embodiments include multiple dedicated multicast cards, allowing rapid simultaneous expansion of the multicast tree.

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What is claimed is: 1. A method of multicasting a data packet from a single input to multiple outputs of a router system having a switching fabric, comprising: transferring the data packet to be multicast (multicast packet) from a router input to a dedicated multicast output card; transferring said

What is claimed is: 1. A method of multicasting a data packet from a single input to multiple outputs of a router system having a switching fabric, comprising: transferring the data packet to be multicast (multicast packet) from a router input to a dedicated multicast output card; transferring said multicast packet from said dedicated multicast output card to a dedicated multicast input card; storing said multicast packet on said dedicated multicast input card; and transferring said stored multicast packet from said dedicated multicast input card to said multiple outputs of said router system, wherein said multicast packet is replicated to produce a replica packet, wherein said switching fabric contains multiple inputs and said multiple outputs connected through multiple parallel switching paths, wherein multiple replica packets are transferred in parallel to said multiple outputs during a single cycle of said switching fabric, and wherein said multicast packet is sent through said switching fabric times wherein N is the quantity of said multiple outputs, wherein m is the quantity of said multiple parallel switching paths, and wherein the CEILING function rounds the value of a variable up to the next higher integer. 2. The method of claim 1, wherein said dedicated multicast output card and said dedicated multicast input card are combined into a single dedicated multicast card. 3. The method of claim 1 wherein said replica packet is produced at a location selected from the group consisting of said dedicated multicast output card and said dedicated multicast input card. 4. The method of claim 1 wherein said multicast packet is converted from an electrical packet to an optical packet at said dedicated multicast input card. 5. The method of claim 1 wherein said multicast packet is transferred from said dedicated multicast input card to said multiple outputs through said switching fabric. 6. A method of multicasting a data packet from a single input to multiple outputs of a router system having a switching fabric, comprising: transferring the data packet to be multicast (multicast packet) from a router input to a dedicated multicast output card; transferring said multicast packet from said dedicated multicast output card to a dedicated multicast input card; storing said multicast packet on said dedicated multicast input card; and transferring said stored multicast packet from said dedicated multicast input card to said multiple outputs of said router system, wherein said multicast packet is transferred to said dedicated multicast output card through said switching fabric, wherein said multicast packet is transferred substantially simultaneously to a plurality of dedicated multicast output cards through said switching fabric, wherein said multicast packet is transferred from a plurality of dedicated multicast input cards to said multiple outputs through said switching fabric, wherein said switching fabric contains multiple inputs and said multiple outputs connected through multiple parallel switching paths, wherein said multicast packet is replicated to produce a replica packet, wherein multiple replica packets are transferred substantially simultaneously in parallel from said plurality of dedicated multicast input cards to said multiple outputs during a single switching cycle of said switching fabric, and wherein said multicast packet is sent through said switching fabric times, wherein N is the quantity of said multiple outputs, wherein M is the quantity of said plurality of dedicated multicast cards, wherein m is the quantity of said multiple parallel switching paths, and wherein the CEILING function rounds the value of a variable up to the next higher integer.