Interfacing to SAR devices in ATM switching apparatus

Switching apparatus, for use in an ATM network, comprising:

• a switch fabric for switching ATM cells;
• a segmentation portion for segmenting a packet generated locally in the apparatus into a plurality of ATM cells;
• and
• a traffic management portion connected by a first data delivery path to said switch fabric and by a second data delivery path, separate from said first data delivery path, to said segmentation portion, and operable to receive from the switch fabric via said first data delivery path cells that have been switched by the switch fabric and to receive from the segmentation portion via said second data delivery path the cells of said plurality, and to output an ATM cell stream comprising the switched cells received from the switch fabric and the cells of said plurality received from the segmentation portion.

A traffic management device, for use in an ATM switching apparatus having a switch fabric for switching ATM cells delivered to the apparatus and also having a reassembly portion for reassembling packets from ATM cells delivered to the apparatus, the traffic management device comprising:

• a cell receiving portion for receiving ATM cells;
• a cell identification portion connected to said cell receiving portion and operable to identify as respective reassembly cells those cells amongst the received cells that require reassembly by said reassembly portion of the apparatus;
• and
• a cell output portion having a first port portion adapted for connection, when the device is in use, to said switch fabric, and also having a second port portion, separate from said first port portion, adapted for connection when the device is in use to said reassembly portion, and operable to deliver received cells other than the identified reassembly cells to said first port portion and to deliver said reassembly cells to said second port portion.

Switching apparatus, for use in an ATM network, comprising:

• a switch fabric for switching ATM cells;
• an internet-protocol switch controller portion for detecting internet-protocol flows through the switching apparatus;
• a traffic management portion connected for receiving ATM cells delivered to the apparatus and also connected by a first data delivery path to said switch fabric and by a second data delivery path, separate from the first data delivery path, to said internet-protocol switch controller portion, and operable, in a default routing mode thereof, to identify, as default-routing cells, those received ATM cells that make up packets not detected as belonging to such an internet-protocol flow and to deliver those cells via said second data delivery path to said internet-protocol switch controller portion;
• and
• the traffic management portion also being operable in a cut-through switching mode in which the received ATM cells that make up packets belonging to such an internet-protocol flow are delivered directly to said switch fabric via the first data delivery path.

A traffic management device, for use in an ATM switching apparatus having a switch fabric for switching ATM cells delivered to the apparatus and also having internet-protocol switch controller portion for detecting internet-protocol flows through the switching apparatus, which device comprises:

• a cell receiving portion for receiving ATM cells;
• a cell output portion having a first port portion adapted for connection, when the device is in use, to said switch fabric, and also having a second port potion, separate from said first port portion, adapted for connection when the device is in use to said internet-protocol switch controller portion;
• and
• a cell identification portion connected to said cell receiving portion and operable, in a default routing mode thereof, to identify, as default routing cells, those received ATM cells making up packets that have not been detected as belonging to such an internet-protocol flow and to deliver those cells to said second port portion for transfer to the internet protocol switch controller portion, and also operable in a cut-through switching mode in which those received ATM cells making up packets that have been detected as belonging to such an internet-protocol flow are delivered to the first port portion for transfer directly to the switch fabric.

A switching method, for use in ATM network switching apparatus that comprises a switch fabric for switching ATM cells, a reassembly portion for reassembling packets from ATM cells, and a traffic management portion for receiving ATM cells delivered to the apparatus, said method comprising:

• identifying cells amongst the received ATM cells that require reassembly by the reassembly portion by the traffic management portion as respective reassembly cells;
• delivering received cells other than such identified reassembly cells by the traffic management portion to the switch fabric via a first data delivery path;
• switching the delivered cells by the switch fabric;
• and
• delivering the identified reassembly cells are from the traffic management portion to the reassembly portion via a second data delivery path separate from the first data delivery path, and reassembling the delivered and reassembled cells into packets by the reassembly portion.

A switching method, for use in ATM network switching apparatus that comprises a switch fabric for switching ATM cells, a segmentation portion for segmenting a packet generated locally in the apparatus into a plurality of ATM cells, and traffic management portion for outputting switched cells, said method comprising:

• receiving cells that have been switched by the switch fabric by the traffic management portion from the switch fabric via a first data delivery path;
• receiving the plurality of cells produced by the segmentation portion by the traffic management portion via a second data delivery path separate from said first data delivery path;
• and
• outputting an ATM cell stream, comprising the switched cells received from the switch fabric and the cells of said plurality received from the segmentation portion, by the traffic management portion.